new bus has a 120VAC or propane water heater. Propane is not hooked up, since the water heater is currently installed inside the luggage bay. The question is, how do people normally install propane hot water heaters into buses (MC-5C). The luggage bay is where all the rest of the water system is, but it seems poor practice to not have the propane side open to the outside all the time. Do people simply forego having a propane water heater, or do they cut a hole in the side of the bus to install it open to the outside as with a normal RV?
Second question - venting the grey/black tank. My tank appears to be vented to the underside of the bus, or into the rear axle space, which I suppose is technically the underside. I think that would be acceptable for a grey only tank, but I think that a black tank needs more venting and the vent should be on the roof. What is the advice?
Thanks, Brian
If you are going to use an RV propane water heater, then yes, the only option is to cut a big ugly hole in the side of your bus.
If, on the other hand, you want to stay with electric, then I would replace it with a the largest electric water heater you can fit in the bay. I had a 20 gallon unit and even after a day or so without power, you could still get a couple of quick showers (in moderate weather, of course).
As for the tank vent, if it ain't broke, don't fix it. If you do have an odor problem, then consider taking it up through the roof.
I have a neat hole covered in mesh for the heater, painted to match its not obvious.>>>Dan
If you are going to replace the LP water heater, as Len suggests, then you might consider a marine model with a heat exchanger.
These units will run on 120VAC when it is available, but can also be plumbed into either a house hydronic system if you plan to have one, or, if not, directly into the engine coolant loop. I would tee off the heater take-off and put a gate valve in line to control how much coolant flows through the water heater vs. forward to the heaters. With this arrangement, you will get free hot water while you are driving.
As for your waste tanks, they are required to be vented through the roof. In addition to the tanks being vented this way, every fixture drain must also be vented to the roof. Separate vents are not necessary -- vent pipes can be combined below the roof line, so long as they join above the flood rims of their respective fixtures.
-Sean
http://OurOdyssey.BlogSpot.com
I pondered the same question re your hot water heater for quiet sometime. I actually mounted it in the rear cargo bay with my water, after quite sometime I broke down and mounted up in the side with that big ugly hole that Len is talking about. The hot water tank now sits in my lower kitchen cabinets and is vented to the outside at all times. I am happy with the installation.
As far as venteing goes, I agree , if it's not broke don't fix it. However if you are getting fumes it's broke.
I vented mine staight up through the roof. The pipe runs through a bathroom floor to ceiling closet. Works well.
Grant
I have done all of these things successfully. I have a propane hot water under my kitchen sink vented to the outside. I also have a marine unit just like Sean describes plumbed into the heater loop. I put valves on the water lines so that I don't have to shove my hot water from either source all the way through the one that is not being used. I vented my black water tank through the passage behind the fridge and out the plastic cap of the fridge vent. Didn't need an extra hole in the roof. I sent the grey water vent through the rear wheel well. No smell in the first year of use.
Glenn
The setup I have is two 10 gal water heaters straight from Home Depot (no heat exchanger). One is plumbed to the next with the final one run through the inverter for heat during the day going down the road. I like it so much, I'm using the same setup on my next conversion. Except for draining once a year, no maintenance in the 14 years they have been in. Plus they are cheap. Good Luck, TomC
as mentioned think about a marine unit.
Marine units are built with vibration and jaring in mind and with the heat exchanger you can get several showers with SUPER hot water right after driving and as also mentioned well after stopping too.
Bottom waste tank vents work fine, both black and grey. I have this setup and so do quite a number of others. Sure beats a hole in the roof.
Just make sure it has a loop that carries it above the waste liquid level.
A bottom vent also serves as an overflow.
Quote from: gus on June 01, 2009, 07:57:05 PM
Bottom waste tank vents work fine, both black and grey.
Works fine, right up until it doesn't, and then your coach explodes from methane build-up, or you get killed due to some other noxious gas.
This is the reason why it is not allowed.
Quote7.7.6.1 Roof Extension. Except as otherwise permitted in this standard, each vent pipe shall pass through the roof and terminate vertically, undiminished in size, not less than 2 in. (50.8 mm) above the roof. Vents terminating on curved roof recreation vehicles or recreation vehicles with elevating tops must pass through the roof or upper side of the recreation vehicle at a point as high as practicable and not less than 6 ft from the ground level.
(Forgive me, my code book is a bit out of date. The above is from the 2002 edition.)
QuoteA bottom vent also serves as an overflow.
Overflows are not permitted on waste tanks. That opens up the possibility of putting raw sewage on the ground.
FWIW.
-Sean
http://OurOdyssey.BlogSpot.com
Sean, what code book are you referring to? I think I'd like to get a copy.
Thanks everybody, I appreciate the help and advice.
Brian
Quote from: bevans6 on June 02, 2009, 06:41:37 AM
Sean, what code book are you referring to? I think I'd like to get a copy.
ANSI/NFPA 1192, which covers everything in an RV except the electrical systems (which are covered in the National Electric Code, NFPA 70). Lots of good information not only on waste and water plumbing, but also LP (propane) systems, emergency exit requirements, "toy hauling" compartments, heaters, and more.
It can be downloaded in PDF format from NFPA or ANSI for about $35.
-Sean
http://OurOdyssey.BlogSpot.com
Why would methane build up in a bottom vented tank any more than in a top vented one as long as the vent is open?
If the vent is plugged there is no difference.
Does this code book apply to bus private bus conversions?
If a waste tank overflows where does the excess go?
Code book always rite so mone all go through the roof. certainly was not a problm to do as i designed to pass through a closet. Jerry
Quote from: gus on June 02, 2009, 01:26:00 PM
If a waste tank overflows where does the excess go?
If you have a combination waste tank that is installed properly with a vent through the roof, the tank will back up into the shower (lowest opening the the contents can escape through), If you have a separate black tank, when you try to flush the toilet (RV type), you will see tank contents in the bottom of the toilet. Jack
Hi guys,
I purchased one of those instant hot water heaters from ebay and have not installed it yet. From what I understand they work quite well, no power draw, no ugly hole in side of bus.
As far as the code goes... I am probably one of those guys who should get the book - oops!
Quote from: gus on June 02, 2009, 01:26:00 PM
Why would methane build up in a bottom vented tank any more than in a top vented one as long as the vent is open?
Methane gas is lighter than air. In a proper always-rising vent, the methane rises out the top of the vent and continues rising, dissipating in free air.
If you loop the vent line so that it goes down, the methane will rise to the top of the loop and remain there, which is, itself, a hazard.
Furthermore, when enough gas emits from the tank to finally push the methane out the bottom vent, the methane will be below the coach, and it will rise through any openings right back into the bus. Depending on air currents, etc, it could rise right into a compartment with spark-producing equipment and cause an explosion.
Lastly, whether it is methane or anything else, most sewer gases rise, so when they finally get pushed out the bottom vent, they will rise into the coach, where they can make someone ill or worse. Gases will also tend to build up in the tank without a continuously rising vent, and, ff you have a trapless RV toilet (which is most of them), some of that gas will rise back into the coach when the flush gate opens.
Quote
If the vent is plugged there is no difference.
Plugged vents are a problem. If you do not use your rig daily, I recommend inspecting the vents before every trip. This is a poor justification for doing the venting unsafely and in contravention of accepted codes and standards.
Quote
Does this code book apply to bus private bus conversions?
Depends on the state. Not all states have adopted all parts of this code. I don't have a list, but if you Google the code on government sites, you can get a general idea of just how widely accepted this code is:
http://www.google.com/search?q=nfpa+1192+site%3A.gov (http://www.google.com/search?q=nfpa+1192+site%3A.gov)
(Note that many states, counties, and municipalities do not have ".gov" domain addresses, so this search is extremely incomplete -- it's just to give you a sense.)
But why would you want to do something unsafely just because the state you happen to be in is lax about this sort of code enforcement? I can assure you that they are not as lax when it comes to vents in fixed structures -- vents must
always rise continuously to the outdoors. It's only because privately built RVs are such a tiny fraction of their overall jurisdiction that they pay little attention -- they know that manufactured RVs are already built to this code.
Quote
If a waste tank overflows where does the excess go?
It is unlawful in all 50 states for your black waste tank to overflow. Some states are more lenient about gray waste.
As has already been written, if you overfill the black tank, it will back up into the toilet. If you overflow the gray tank, it will back up into the shower pan.
This is one reason I recommend against combined tanks, BTW -- in a combined tank system, when the tank overflows, raw sewage including black waste can back up into the shower pan. Yuck. (The other reason is that if your P-traps happen to empty, due, say, to driving conditions, then sewer gas from the black tank can back up into the rig. Even if you have separate tanks, I recommend priming all your traps whenever you stop and get leveled.)
-Sean
http://OurOdyssey.BlogSpot.com
If Methane is present it makes pressure so it is always flowing from the vent, even the slightest pressure will push it our a bottom vent. The pressure won't build up and suddenly push accumulated gas out the vent.
I have never smelled any gas from my vent, even the slightest breeze will dissipate the gas so the chance of it ever being concentrated is nil.
My toilet flows to the bottom of the tank, no methane comes out my toilet.
Do you inspect your rooftop vent before every trip?
So far I haven't seen or read anything that says a bottom vent is unsafe. If I thought it was unsafe I wouldn't do it.
There are a number of other busnuts with bottom drains and none of them have ever posted about any problems.
Vents in fixed structures are there primarily to prevent a vacumn in the drain system, not to release gas. These vents actually take in air rather than vent it out. Traps keep out the gas.
Quote from: gus on June 03, 2009, 10:44:37 PM
If Methane is present it makes pressure so it is always flowing from the vent, even the slightest pressure will push it our a bottom vent.
That's not correct. Methane can sit in the top of a loop of pipe for hours. It does not "make pressure" -- only the generation of additional gas inside the tank will create additional pressure.
QuoteThe pressure won't build up and suddenly push accumulated gas out the vent.
I did not say it would. I only said that when additional gas is produced, the methane would be pushed out the bottom and then immediately begin to rise, possibly back into the coach.
Quote
I have never smelled any gas from my vent, even the slightest breeze will dissipate the gas so the chance of it ever being concentrated is nil.
My toilet flows to the bottom of the tank, no methane comes out my toilet.
So far I haven't seen or read anything that says a bottom vent is unsafe. If I thought it was unsafe I wouldn't do it.
There are a number of other busnuts with bottom drains and none of them have ever posted about any problems.
All four of those statements represent a common logical flaw -- since I've never had a problem, and other people I know have never had a problem, and we've been doing it this way for a long time, it must be safe. The problem with that reasoning is that many things are safe, and cause no problems, 99% or 99.9% or even 99.999% of the time. Yet history is full of tragic tales of problems that could have been avoided had people just known what could happen, even though some things don't happen often. Codes are created for exactly this reason.
Quote
Do you inspect your rooftop vent before every trip?
I don't go on trips, I live in my bus full time, so there is no opportunity for nests to get built, etc.. But that's not really germane to the discussion, now, is it? We weren't talking about routine inspections, we were talking about design and construction standards. I suspect many people don't inspect their running lights every day (although I do), either, but that does not relieve the coach builder of the obligation to install them.
Quote
Vents in fixed structures are there primarily to prevent a vacumn in the drain system, not to release gas. These vents actually take in air rather than vent it out. Traps keep out the gas.
This, too, is incorrect. If vents only needed to admit air to prevent vacuum, there would be no need to run them to the roof (as is required by the Uniform Plumbing Code), and every fixture could just have an AAV on it. All waste lines are required to be vented to the outside in order to vent sewer gases. Try venting your sewer line into your living room for a while, and I am sure you will soon notice that, indeed, sewer gas comes out.
Proper traps keep gas from flowing back out of the stack and into the structure through the fixture drain. But each time a fixture drains, gases in the waste lines are displaced, and those gases have to have some place to go. That place is up and out the vent stack.
Code (both the RV kind and the UPC) even dictates the size of vent lines and stacks all the way to the roof.
Lastly, I have already pointed out the exact code requirement in black and white. So it is indisputably the law, at least in most jurisdictions. And I can assure you that the equivalent requirement in the UPC for fixed structures actually is the law in every jurisdiction in the US.
And now, you can no longer say that you have never read anything saying a bottom vent is potentially unsafe -- you just read it right here.
-Sean
http://OurOdyssey.BlogSpot.com
I'm the OP, and want to thank everyone, especially Sean, for the discussion. Really confirming things I already knew, at least from a house point of view, but wanted to double check. My black tank is currently vented into the top of the rear axle compartment, which forms the floor of the bedroom, said floor is probably not proof to incursion from sewer/methane gasses. At least it was vented somewhere...
Today's job is to start to re-plumb the coach, fixing issues (like that one, and having the water pump installed by dangling it from it's lines in mid air), start to plan for cutting the fridge side access panel, and a few other things. Even if I have to fix a few things, it's a whole lot easier than starting a conversion from scratch!
Brian
I have been reading this and as always Sean is a walking bag of knowledge or at least knows where the answers to code questions are, but what I did was to go out to my bus which still has the original holding tank and I'm still looking for the vent. How did a commercial transport bus get built, run and carry upwards of 40 people at a time without a vent going thru the roof? I'm sure Prevost not to mention all other transporters were built unsafe to carry these people! So if their vent didn't go thru the roof so the methane gases could go upward into the atmosphere, then just where did it go? Is there another means of venting the large SS "combined" holding tank that is oem on mine and I'm sure other buses?
Just curious!
Ace
Ace,
I'm not sure about your H3, but the Prevost's that we saw in Ohio had a 3/4" or 1" hose running from the factory lavatory waste tank up to the vent on the back of the bus where the cap comes down.
I think the reasoning was that since these weren't motorhomes, but used mainly for the transport of passengers, the only regulations they needed to follow were DOT and NTSB.
I've seen the same typr of vent hose on MCI and Setra and VanHools.
YMMV
Dallas
(Smoke - Groan) ;D
If you're cutting holes in the baggage door panels IBP may be able to supply panels with vents so it will look more like the factory style panels. If you have any questions please don't hesitate to call me at 1-800-468-5287 x232
Thanks
Steve
Dallas I have looked and looked with out finding any type of vent in or around the cap area or any type of hose! Besides if they used a hose that small would it be sufficient? Everyone is saying it should be 2 inches!
Ace (not smoking OR groaning YET) ::)
Quote from: Blacksheep on June 04, 2009, 07:45:16 AM
... Sean is a walking bag of knowledge ...
Interesting choice of words, Ace...
Quote
... my bus which still has the original holding tank and I'm still looking for the vent. How did a commercial transport bus get built, run and carry upwards of 40 people at a time without a vent going thru the roof? ... So if their vent didn't go thru the roof so the methane gases could go upward into the atmosphere, then just where did it go? Is there another means of venting the large SS "combined" holding tank that is oem on mine and I'm sure other buses?
As Dallas wrote, there should be a vent hose leading up from the tank if you hunt around.
That said, this type of toilet is very different from an RV model. Many have no trap or flapper, and so the tank is open to the inside of the coach at all times, with only possibly the toilet seat in the way. This type of toilet system
must have a fairly strong chemical additive in it, one function of which is to break down the waste chemically, rather than bacteriologically. One of the safety issues with inadequate venting is the possibility of airborne pathogens entering the living space, and this, too, is mitigated by the strong chemical disinfectant. Another key difference with passenger coaches is that, typically, waste does not remain in the tank even overnight -- most motor coach restrooms are emptied at the end of every day.
Lastly, in general, a passenger motor coach does not constitute a living accommodation, so the safety issues are different. For example, food preparation is usually not done, nor are all the occupants generally sleeping on board.
All of that said, I don't know about you, but I would not want a bus-type toilet for my house. In part, that's because the venting is really not adequate for the purpose, as anyone constrained to spend an entire bus ride in row 14 can attest.
-Sean
http://OurOdyssey.BlogSpot.com
Sean the bag word just came out as habit and not meant to be disrespectful. You know like bag of bones, Ole bag, etc! all in fun!
With that said, back to the vent!
You said that all buses are usually emptied every night! Hmm, when camping with full hook ups, in a livable bus, the waste tank is merely a pass thru with nothing much if anything at all staying in the tank!
Also you said that buses must have a very strong chemical additive to help break down the waste. How many times have we read here that additives are not needed or good for that matter? Why would bus companies do this IF it's not a good idea?
As always I am probably a little confused as to the contradicting reports here such as flapper, no flapper, large vent, small vent, Vent up, vent down, additives, no additives, smell, no smell!
All in all, a toilet is a toilet. It does one thing. Gives you a place to deposit your waste. I can't imagine a BUS toilet not having some sort of seal such as a flapper or valve other than the toilet seat to seal off what odors etc. may rise upward from the holding tank! Also why don't bus builders that build buses for transporting people, have separate holding tanks for gray and black? Mine was a combined tank! Another thing I was told was the wrong way to go!
Bottom line is, if it (the tank, toilet, vent was good enough to have in a bus to transport 40 plus people and approved for use, why wouldn't a similar set-up work for a couple 2-3-4 people on a camping trip? I mean they will probably let it all out once they hook up to the camp sewer! I ALWAYS drain my tank either before I leave for home or while I am camped! How can this be unsafe?
My 2 inch vent goes downward thru the floor of the bay and rearward. I have YET to see, smell or have any type waste problems with this set-up! Notice I didn't say YET? I don't see any problems arising anytime with the way my system is designed! I would really hate to see anyone put un-necessary holes in a roof of a bus if they didn't have to!
Sorry but sometimes, as I have said many times before, people need to look OUTSIDE the box! I agree codes are written for various reasons but even the game checkers has rules that are supposed to be followed but very often they are challenged with the two playing parties! The point is, not everyone follows the rules and I doubt very seriously that someone will have their bus blow to smitherines because they vented down instead of up!
Again... just my opinion!
The original toilet on my bus, 1990 102A3, was as Sean described an "out-house". Just a toilet seat covering the 9" diameter hole to the tank. These tanks were dumped every day, but the real reason that the oder did not enter the coach is that the tank was vented the the air cleaner and the the engine ran all day. As long as the engine "sucked" on the tank there were no oders. This was not the case when I first used the coach on a 4 day run and shut the engine off when not driving. Household bleach came to the rescue. Many people asked me why we all remove the original toilet. I tell them that "I did not want an 'Out-House'" in my moterhome.
Dan
Quote from: Blacksheep on June 04, 2009, 09:18:04 AM
You said that all buses are usually emptied every night! Hmm, when camping with full hook ups, in a livable bus, the waste tank is merely a pass thru with nothing much if anything at all staying in the tank!
If you always have full hookups, then there is no need for a tank at all. The rules and best practices are formulated based on the idea that an RV is self-contained and can, theoretically, be used for a period of several days without hookups. As such, they need to be set up properly for this usage. Moreover, as I am sure you know, a sewer connection is the least common type of hookup -- many, many parks providing electricity and water do not provide sewer, or sewer is provided only in certain premium spaces, and, instead, the park has a dump station. I would say that 97% or so of the times we have had electricity available, there has been no sewer hookup.
As a separate note, I will point out that even if you always choose a site with sewer, generally you should not leave your black valve (or combined valve if so equipped) open. You should keep the valve closed until the tank is at least a quarter full or so, and re-close the valve after dumping. This is to prevent the build-up of solids in the tank. So even with full hookups, a proper vent is still required.
Quote
Also you said that buses must have a very strong chemical additive to help break down the waste. How many times have we read here that additives are not needed or good for that matter? Why would bus companies do this IF it's not a good idea?
You are comparing apples and oranges -- RV toilets and bus toilets are very different. Bus sanitation systems are required to use chemical disinfectant (and note that this is different from deodorizer, which is often the only thing RV tank additives contain). I am talking, here, about a standard coach restroom, not a bathroom in any kind of conversion, to include entertainers or executive coaches, which usually have RV-style bathrooms.
Quote
... I can't imagine a BUS toilet not having some sort of seal such as a flapper or valve other than the toilet seat to seal off what odors etc. may rise upward from the holding tank! ...
Then I submit you have not used the restroom on very many passenger buses. I try to stay out of them myself, but that didn't stop me and most of the other ~40 people on a 96A3 from coming down with a norovirus en route from Prudhoe Bay to Fairbanks. Many were hospitalized, and my wife and I spent two days of misery in a Fairbanks hotel.
Quote
Bottom line is, if it (the tank, toilet, vent was good enough to have in a bus to transport 40 plus people and approved for use, why wouldn't a similar set-up work for a couple 2-3-4 people on a camping trip? I mean they will probably let it all out once they hook up to the camp sewer! I ALWAYS drain my tank either before I leave for home or while I am camped! How can this be unsafe?
Again, the designer or builder of an RV can not assume that tanks are drained frequently. Nor can the "good enough for a passenger bus" reasoning be applied to something which is not a passenger bus -- they don't have seatbelts either, but many states require them at all "travel" seating positions in an RV. Declaring your Prevost to be an RV exempts you from many rules you would be subject to if it were a bus, such as having a class-B CDL with air brake (and passenger, as applicable) endorsement, keeping an hours-of-service log, and stopping at scales and inspection stations. And it subjects you to other rules, such as NFPA-1192, that are not applicable to passenger buses. You can't cherry-pick just the rules you like from both categories.
Quote
My 2 inch vent goes downward thru the floor of the bay and rearward. I have YET to see, smell or have any type waste problems with this set-up! Notice I didn't say YET? I don't see any problems arising anytime with the way my system is designed! I would really hate to see anyone put un-necessary holes in a roof of a bus if they didn't have to!
Not wanting to put a 1.5" hole in the roof is, IMO, a poor reason for failing to follow safe, accepted, and compliant practice in the industry.
It is extremely unlikely that any problem will arise from a downward vent. However, I will point out that it is extremely unlikely that an airplane will crash-land in the ocean, and even less likely that anyone would survive the event, less likely still that any survivors will make it out of the airframe alive and safely. Probably all of these things are less likely than someone getting sick from sewer gas in an RV. Yet still we require airlines to carry life rafts -- for something that will probably never happen. Now ask the folks who survived the ditching of Cactus 1549 if they were glad such a regulation existed.
As I have said here many, many times, these rules, which constantly evolve over time, do not really exist to prevent problems that are common or could be commonly anticipated by the average person. They exist to prevent generally
unlikely problems that have demonstrably happened in the past to someone's detriment. I will further tell you that such rules usually do not get codified until many such problems have occurred.
Quote
Sorry but sometimes, as I have said many times before, people need to look OUTSIDE the box! ... The point is, not everyone follows the rules and I doubt very seriously that someone will have their bus blow to smitherines because they vented down instead of up!
So, what you are saying is that the rules don't apply to you, or maybe to bus nuts in general, and we should all be free to do things however we wish, so long as we personally believe it is safe. While that is a lofty ideal and might work if absolutely everyone who built anything had the technical chops to do it right and safely every time, history has proven otherwise, and society long ago decided collectively not to allow this. Just try to build a house in any municipality in this country without following the rules, and see how far you get. Or perhaps something closer to home -- try to make a race car without following any rules, then show up at the track without proper safety equipment, and see if they let you race. The line has to be drawn somewhere, and in the field of constructing living accommodations, whether those are mobile or not, those lines are very clear.
No one follows every rule, not even me (gasp). But I maintain that it is irresponsible for anyone to come here and deliberately advise people to do otherwise -- especially if those people being so advised are already unsure enough of how to do things correctly and safely that they are asking questions here.
If you are starting from scratch, following the accepted practices adds only minimal expense and inconvenience -- why would you want to risk anything at all to save a few dollars?
-Sean
http://OurOdyssey.BlogSpot.com
As it stands today, the powers that be are quite lenient with us. No special license or test to drive a twenty ton bus, the insurance companies don't look too close at what we build, or what codes were followed.
If there were to be a rash of accidents and/or lawsuits with bus conversions and anyone ever put two and two together, you can bet that would (and probably will) change.
It behooves all of us to use due care and diligence in designing and building our coaches. Fortunately, most folks on these forums do care. Unfortunately, there are many out there that do not belong to our groups, nor do they care.
Len
First of all nobody came here at least I didn't and insinuate that I didn't care how things were done! I think people should take notice on what's done right or wrong and especially if its a safety issue! As Sean stated, very unlikely a downward vent will cause major problems and in telling someone that it CAN be done because it HAS been done is not advising someone to do something that will harm them!
What I truly think is that rather than worry whether your vent goes in the proper direction, some people should take a really close look at what THEY are driving on the road! How many buses have you seen at a rally up close and personal and ask yourself how in the heck did it make the trip? Now that is something people should look at! Tires, brakes,major oil spots from leaks on the engine, air leaks that are clamped with vice grips, broken windshields, doors that don't close and lights litterally hanging off the bus yet they still drive them on yours and my roads. You get my point I'm sure! What's more important? A safe ride or a toilet vent?
I'm not saying the codes are a bad thing and everyone should follow them to a T. Heck even our resident code meister admits to not following the rules entirely so what makes you think everyone else has or will for that matter?
Even noobs are going to see on other conversions that there are other SAFE ways of doing things that actually work.
So you can preach until the cows come home. Your not going to convince NOOBS or OLDS to follow the book!
Ace
Ace,
I agree completely. It's scary when someone asks electrical stuff because they have no idea how it should be done. It's a whole lot scarier when they ask those questions about brakes. ....Oh, brakes need to be adjusted, I didn't know that!
I've seen some charter and entertainer buses that I wouldn't ride on.
Now, as to our buses, I can get worked up about electrical and propane. Frankly, I don't much care how someone else does their sewer vent. It is highly unlikely that it will impact me, and if it does, I can move.
A hot skin or fire on the bus parked next to me is a concern.
I'm an OLD and I'm convinced.
Len I'm in agreement with you too but we sort of swayed from the plumbing issue!
My point was, there are a whole lot more important things on a bus to worry about than following a code for a vent tube!
Ace
Quote from: Blacksheep on June 04, 2009, 03:13:34 PM
My point was, there are a whole lot more important things on a bus to worry about than following a code for a vent tube!
Ace, I agree with this completely. I'm not trying to make a mountain out of a molehill, I'm just responding to the arguments that there is no reason for the concern -- if there were really no reason for it, it would not be in the code. And, frankly, some of the counterarguments advanced have just been plain wrong, and I think people who come here for information and learning deserve to hear the facts, not speculation.
If someone came to me for advice with an existing bus that was not properly vented, I would inspect it and make an informed guess about whether or not it was a big enough concern to warrant tearing things out to fix it. I would not blindly say it has to be changed (although a code inspector might do just that). I can probably even say the same thing about some electrical concerns. But if people are starting from scratch with an empty shell, there is really no excuse for not doing it correctly from the beginning.
-Sean
http://OurOdyssey.BlogSpot.com
Quote from: Sean on June 04, 2009, 04:36:32 PM
But if people are starting from scratch with an empty shell, there is really no excuse for not doing it correctly from the beginning.
-Sean
http://OurOdyssey.BlogSpot.com
If some one is wanting to convert a bus, it is better if they understand the system they are installing BEFORE the installation. Once they know the preferred way, they are better able to make an informed decision as to what 'their way' is.
Ignorance can be cured, but there ain't no fixing stupid. ;D
We're talking two kinds of vents here, drain vents and waste tank vents.
I repeat, the primary purpose of a building drain vent is to take air in, not vent methane. Traps keep methane out of a building. The reason vents go through the roof is because they must be kept higher than the highest drain, not because they vent methane. This is a common myth and may even be believed by some plumbers.
Drain vents in an RV serve the same purpose, without them the traps would be sucked dry every time water went down the drain system. These vents could go out the side of the RV if desired since they take air in, not out. Check valves can also be used which take air from inside the bus and avoid more roof holes and long vent pipes. I use these valves.
A waste tank vent is slightly different but not much. This vent allows sewer gas to evacuate as the tank is filled with liquid and allows fresh air to enter when the tank is emptied. Without this vent the tank would bulge when filling and collapse when being emptied.
The reason for large building roof vent pipes is that the vents are so long and the drain pipes so large that a small vent pipe would not allow enough air to enter the drain pipe as the liquid flowed out. My bottom vent pipe is only 1.25" and perfectly adequate because it is so short.
Any pressure of any kind in a waste tank will evacuate methane if it is present, including incoming liquid. The theory that it will accumulate in the loop is just a theory, nothing more. The theory that there is enough methane in an RV waste tank to be hazardous is also just theory, nothing more.
If anaerobic bacteria is allowed to grow in an RV waste tank there won't be any significant methane, or solid waste for that matter. The problem is that most RVers seem to insist on cleaning the waste tank at every dumping or adding strong chemicals. Bad. This kills the little ab who will do the job much better if only allowed to live. I never completely empty my waste tank.
There is nothing to indicate that methane in an RV waste tank is a problem. I've never heard of an RV explosion caused by methane?? I've also never heard of a methane explosion in a home for that matter. Just because it is posted here that it is a danger doesn't make it so. These are opinions.
Saying that a bottom vent is incorrect or unsafe is baseless. Saying it is doesn't make it so. I'm always amazed when a poster says another poster is wrong with no base for such a statement. Disagreeing is one thing, saying another poster is wrong is another thing altogether and not necessary. I was under the impression that we post here for the information of the questioner and that it was up to him to decide what is right and what is wrong?
Codes are very often more political than technical or safety based. Copper vs PB water supply pipes is the best example I can think of. PB is superior in every way to Cu yet it is not approved in many location. Why? Because it protects the Cu suppliers.
One can make a choice, blindly follow mindless codes or think! It is easy to follow mindless rules and regulations but a bit more challenging to think.
If I thought for a minute that my bottom waste tank vent or my long toilet drain pipe were safety hazards I would change them but so far there has been nothing reliable posted to indicate that. My ole Grandpappy told me long ago to beware of experts and engineers!!
Hello everyone!
I've really enjoyed following the discussion. I never thought a post on waste and venting could be so captivating. There's always something that you can walk away with if you looking. I now know to close the dump valve after the tank is empty when I'm staying hooked up. I don't think anyone mentioned that doing this would also prevent sewage odors from rising into your bus from the massive tank below ground. I know those odors rise when you uncover that tank from experience. If you dare to stand directly over the tank when you uncover it to hook up, prepare to receive the perfume of all those that came before you. I'm a newbie with buses but I've been RVing for years and have experienced that unforgettable aroma on several occasions.
I'll remember to keep my black and gray tanks vented separately. Thanks everyone! :)
Rick
QuoteThere is nothing to indicate that methane in an RV waste tank is a problem. I've never heard of an RV explosion caused by methane?? I've also never heard of a methane explosion in a home for that matter. Just because it is posted here that it is a danger doesn't make it so. These are opinions.
I did a google search. the first thing to come up
Debris from the Makati mall explosion last Friday that left 11 people killed, 112 wounded and three others missing show signs of a possible methane gas explosion,
http://www.gmanews.tv/story/65439/Blast-site-shows-signs-of-methane-explosion (http://www.gmanews.tv/story/65439/Blast-site-shows-signs-of-methane-explosion)
Then i searched youtube
Methane house explosion
http://www.youtube.com/watch?v=U5vbcG1lwiQ (http://www.youtube.com/watch?v=U5vbcG1lwiQ)
Its Not a myth
Methane explodes
Quote from: gus on June 04, 2009, 06:01:20 PM
We're talking two kinds of vents here, drain vents and waste tank vents.
In most RVs, my conversion included, these are one and the same. Sure, you could have separate tank and fixture vents, but why run the extra pipe or cut another hole in the roof? For that matter, for most RVs, wet-vented systems are permitted (there are limits on the number of fixtures, and size limits), unlike in most fixed construction. So careful design lets you get by with a single stack for both waste and vent.
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I repeat, the primary purpose of a building drain vent is to take air in, not vent methane.
You keep saying this, but it's only partly correct. Properly constructed vents do both, and I can assure you that the bulk of the gas flow in a sewer vent is out, not in.
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Traps keep methane out of a building. The reason vents go through the roof is because they must be kept higher than the highest drain, not because they vent methane. This is a common myth and may even be believed by some plumbers.
Again, the reason vents go through the roof is to allow sewer gas to escape at a level higher than the living quarters. If what you say was true, we could simply vent waste pipes into cabinets, or even the attic -- yet the UPC is exceedingly clear on this issue: vents must proceed continuously to above the roof line. Period.
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Drain vents in an RV serve the same purpose, without them the traps would be sucked dry every time water went down the drain system.
Yes. But since they are, by definition, also connected to the waste line, they ALSO VENT SEWER GAS. There is simply no way to avoid this and have the vent work properly.
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These vents could go out the side of the RV if desired since they take air in, not out.
Again, gas flows BOTH WAYS in a vent. And the gas that flows out is sewer gas.
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Check valves can also be used which take air from inside the bus and avoid more roof holes and long vent pipes. I use these valves.
What you call "check valves" are referred to in the trade as Air Admittance Valves (AAV's), and discussed in the code as "anti-siphon trap vent devices." They are indeed, permitted in certain situations. However, THEY CAN NOT SUBSTITUTE FOR A VENT THAT GOES ALL THE WAY TO THE ROOF. You still must vent the fixture at the earliest opportunity:
Quote7.7.5 Anti-Siphon Trap Vent Devices. An anti-siphon trap vent device shall be permitted to be used only as a secondary vent ...
(underline emphasis mine).
If you do not know or understand what a "secondary vent" is, I refer you to the UPC.
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...
The reason for large building roof vent pipes is that the vents are so long and the drain pipes so large that a small vent pipe would not allow enough air to enter the drain pipe as the liquid flowed out. My bottom vent pipe is only 1.25" and perfectly adequate because it is so short.
I am not sure what you mean when you say "large building roof vent" -- are we back to buildings, or still talking RV's? Because my code says the vent must be a minimum of 1.25", the same size you used, although adding enough fixtures or certain wet venting requires one trade size higher -- 1.5". But, again, it must go through the roof, as I cited earlier.
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Any pressure of any kind in a waste tank will evacuate methane if it is present, including incoming liquid.
Precisely what I said. And, if that evacuation happens below the coach, then methane and other sewer gases can then rise right back into the coach.
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The theory that it will accumulate in the loop is just a theory, nothing more. The theory that there is enough methane in an RV waste tank to be hazardous is also just theory, nothing more.
Just to be clear, while I have cited the problems involving methane for completeness, my bigger concern (as well as the code's) is not methane itself, but other sewer gases, including hydrogen sulfide, and any pathogens that might be along for the ride. Sewer gases entering residential spaces is a proven problem from which many people have become ill -- it is not a "theory." This is one reason why the codes mandate that vents proceed directly to the roof. A simple Google search will turn up hundreds of cases of people becoming ill and even being hospitalized when sewer gas entered an occupancy space, including school and office closures, residential condemnations, etc.
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If anaerobic bacteria is allowed to grow in an RV waste tank there won't be any significant methane,
Now, this one takes the cake, because the primary byproduct of sewage digestion by anaerobic bacteria IS methane. (By contrast, aerobic bacteria would produce carbon dioxide.)
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or solid waste for that matter. The problem is that most RVers seem to insist on cleaning the waste tank at every dumping or adding strong chemicals. Bad. This kills the little ab who will do the job much better if only allowed to live. I never completely empty my waste tank.
Here, I agree with you -- the health of the tank will be best served by keeping the bacteria alive, which means don't put harmful bacteria-killing chemicals in the tank. But please don't tell us this does not produce methane and other sewer gasses -- this is exactly what it produces.
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There is nothing to indicate that methane in an RV waste tank is a problem.
I would say the code itself indicates that.
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I've never heard of an RV explosion caused by methane?? I've also never heard of a methane explosion in a home for that matter. Just because it is posted here that it is a danger doesn't make it so. These are opinions.
A simple Google search revealed dozens of homes that have suffered methane gas explosions or fires from sewer problems. You can certainly look them up. That's fact, not opinion. As for RV's, well, I confess I could not find any reference to RV explosions due to methane in a brief search. But, again, the primary safety concern is not methane,
per se, but other sewer gases along with airborne biologic pathogens.
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Saying that a bottom vent is incorrect or unsafe is baseless. Saying it is doesn't make it so.
I'm always amazed when a poster says another poster is wrong with no base for such a statement.
It's not "baseless" -- it's in the code. The code is the "basis" for my statements. And, the code makes it "so," whether I say it here or not.
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Disagreeing is one thing, saying another poster is wrong is another thing altogether and not necessary. I was under the impression that we post here for the information of the questioner and that it was up to him to decide what is right and what is wrong?
Gus, I did not "decide" that it was "wrong" -- the code says you should not do it. That makes doing it unlawful. That's what I said -- it was you who contradicted that, and asked for an explanation. Now that I have acceded to your request and explained why the code says what it does (bearing in mind that I did not write the code, I only quoted it), you are accusing me of making things up.
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Codes are very often more political than technical or safety based. Copper vs PB water supply pipes is the best example I can think of. PB is superior in every way to Cu yet it is not approved in many location. Why? Because it protects the Cu suppliers.
Setting aside, for the moment, the fact that I do not buy into these sorts of conspiracy theories, and assuming you are correct, please explain to me who is benefiting "politically" from the requirement to extend RV vents to the roof.
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One can make a choice, blindly follow mindless codes or think! It is easy to follow mindless rules and regulations but a bit more challenging to think.
As I have said on this board many times, I don't buy this notion that any of us can ignore all rules and regulations and do whatever we want simply because we can "think" and that thinking leads us to believe that we know better than the law. That is a slippery slope. Right now, it's plumbing. Later, maybe it's headlights, or air brakes, or propane.
I'm not a fascist, but neither do I want to live in anarchy. I don't want to live in the world you propose, where anyone at all, regardless of qualification, gets to build anything they want.
I would also like to know where you got the notion that the codes are "mindless." That flies in the face of reality, and is disrespectful of the people who have spent countless hours working on them.
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... My ole Grandpappy told me long ago to beware of experts and engineers!!
Great. I invite you to take a ride on an airliner, roller coaster, or elevator designed by people who did not finish engineering school. If you could even find one here in the U.S. -- doubtful, precisely because our concern for the safety of the general public here generally keeps such things from entering service.
Actually, for that matter, you should give up bus ownership right now -- those darn buses were designed by, gasp, engineers.
-Sean
http://OurOdyssey.BlogSpot.com
Many codes were designed because of someones death, so therefore OSHA and others to protect us from making stupid mistakes and saving lives, could be yours! I prefer to be safe and not argue over stuff that has already been thought through. I'm vented thought the roof! And can sleep better at night, wake up in the morning without a headache or worse, not waking up!
~Paul`
There are sometimes many ways one can do something.
But sometimes there is only one right way, like it or not..
Hey, even the porta potty guys run there vent through the roof......
(//)
Cliff that's why they call me Blacksheep! I guess everything I do and have done is wrong and won't work! Stems all the way back to my tanks and how they were done and they would never work but guess what, still hanging, still no leaks and best yet, still haven't killed anyone on the interstate!
I'll just keep my vent going out the bottom of my porta potty and see you down the road!
Ace with his mobile methane conversion!
Geez....
By now, everybody here knows the right way to do it and where to find all the information you will ever need. There is one right way and a hundred less right ways to do it. There can be no argument with doing it right. There are multiple arguments with doing it less right (I didn't say wrong).
I must point out that if I were looking at a used conversion that didn't make an attempt to follow the various codes, I would scrutinize it far more carefully than I might otherwise.
Hey Ace, maybe if you ducted the vent into your engine air intake, all that methane would increase your HP? LOL Jack
Quote from: JackConrad on June 05, 2009, 07:41:41 AM
Hey Ace, maybe if you ducted the vent into your engine air intake, all that methane would increase your HP? LOL Jack
That is kinda what I am wondering...... I dont really want to put holes in my roof either (if not necessary). I have an RTS and my engine is way in the back, so would there be a problem if I ducted my system to vent near the top part of my engine compartment or out the top where the AC is into the already vented area up there (though I guess if I ran the factory AC I would just be throwing the gases back into the living areas)?
Quote from: gus on June 02, 2009, 01:26:00 PM
Why would methane build up in a bottom vented tank any more than in a top vented one as long as the vent is open?
Methane is lighter than air, and odorless. It is not toxic, but displaces oxygen and is explosive in concentrations between 4.5% and 14.5% in free air.
If you are venting below the tank, your vent pipe will trap methane rather than venting it, filling both the pipe and the tank. The only gas to be released will go out through the drains -- into the coach -- or that which is forced out the vent.
Venting upward keeps the concentration below 1% while venting downward puts the concentration at anywhere between 1% - 100%, depending on factors such as when it was last drained. Also, if you are venting under the coach, that methane may get inside through any seam, hole, crack, etc.
Quote from: gus on June 03, 2009, 10:44:37 PM
If Methane is present it makes pressure so it is always flowing from the vent, even the slightest pressure will push it our a bottom vent. The pressure won't build up and suddenly push accumulated gas out the vent.
Not so.
Methane is the primary component of natural gas. It doesn't "make pressure" any more than any other gas, or people wouldn't have to buy it.
Quote from: bevans6 on June 04, 2009, 05:23:41 AM
Today's job is to start to re-plumb the coach,
To make the job less daunting, the vent doesn't have to be large, and can be made with flexible tubing. All that matters is that it taps from the high point in the tank (or near enough to it) and that it vents past the roofline, and rises continuously. That lets you route it where it's convenient.
Quote from: JackConrad on June 05, 2009, 07:41:41 AM
Hey Ace, maybe if you ducted the vent into your engine air intake, all that methane would increase your HP? LOL Jack
Briefly.
It wouldn't take more than a few seconds for all of the methane to be carried into the engine. After that, it would just be air.
In my old 4104, I used 1-1/2" swimming pool vacuum hose and routed it up behind the refrigerator and terminated at the top of the refer vent. No extra hole in the roof.
Since my drain/vent system is probably different than most I have "anti-siphon trap vent devices" (Love that name). I thought "check valve" sounded a bit simpler since that's what it is. My kitchen sink and wash basin are on dedicated drains with AAV's . The toilet and tub are on a different line from those. The main drain empties into the bottom of my waste tank so AAV's are necessary. They are necessary because I can hear them taking in air. Wet vents would not work here because of the distances between fixtures. The PO assured me that the bus was plumbed by a licensed plumber and I had no reason to doubt him, even though it was done in a different code zone.
I said that the primary purpose of a building drain vent is to take air in, not vent methane because my plumbing manual says nothing about sewer gases in that section, all it discusses is taking fresh air in to prevent a vacumn in the system. Since I'm not a plumber I can only assume that gas is not a problem since there is no mention of it. I didn't bring up the subject of building vent systems, this was first introduced under the name of "fixed structures" which, I assumed, means buildings?
Loop vents are allowed by some codes so the accumulation of gas at the top of the loop doesn't seem to be a problem.
We started out discussing the explosive danger of methane but now seem to have changed to sewer gas and odors. Now I read that methane is not the primary concern?? Obviously nobody would vent sewer gas into a living space, otherwise why bother with traps?
I'm pretty sure I could smell sewer gas if it infiltrated the bus!! I'm also certain I can figure out what "secondary vent" means.
It is absolutely correct that methane is the primary gas produced by anaerobic bacteria reaction. It has been many years since I delved into chemistry and I got them reversed. Carbon dioxide is secondary to methane, not primary.
After a bit of research prodded by this discussion it now appears that my RV waste tank may not even have significant anaerobic activity because the waste is agitated so much and so much oxygen is introduced into the tank from the two AAV's, the toilet and the tank vent (when the tank is emptied). It seems anaerobic bacteria don't like agitation. Interesting thought!
I've read articles about sewer fires and explosions, but not ones originating in homes. The problem seems to be in the municipal system, not the home. And, again, never heard of an RV having a methane problem.
Since the building Code is divided into three zones and can be overriden by local codes it seems to me that the people writing these codes can't seem to agree on what is lawful or safe. This leaves me with the impression that in many cases there is more politics and special interest involved than science. I have to assume that the RV code isn't much better since it is based on the building codes.
"And, frankly, some of the counterarguments advanced have just been plain wrong", from a recent post, with no mention of codes, sounds like saying another poster is wrong to me? Forum posts more informative and less indignant would seem to be most beneficial to all.
I don't remember saying or reading any other post saying that we should ignore all rules and regulations and do as we please or that anyone should build anything they want? I do, however, remembering saying that we should think. I hadn't really thought of codes in terms of fascism or anarchy even though they are so rigid and often, to me, not clearly thought through. My house plumber fully agreed that PB is superior in all ways to Cu but said "the code" doesn't allow it. It would be wonderful if these codes could protect us from all but 0.001 % of danger.
My ole Grandpappy said to beware engineers, he didn't say eliminate or ignore them. I have a piece of paper that says I am an engineer, but I don't take it too seriously, and my son is a Boeing aerospace engineer, but he doesn't take his title too seriously either.
Gus
There is another point to consider.
On a structure there is an exit trap and in most jurisdictions an exit vent. This effectively isolates the "air" in the house system from the sewer system. In an RV system the two are the same system.
My $.02
Sweeney15,
Thanks. I wondered about that?
From your post I understand that the exit trap is on the main house line after all house lines and that the exit vent is also there?
I thought that any municipal sewer would have to be vented somehow and isolated from home sewer systems but I didn't know how it was done.
However, I don't understand how a septic tank is vented or isolated? Mine does not appear to have either a trap or a vent except for the drain vents?
It appears to me that fresh air is drawn into my RV system through the drain vents every time liquid flows through the drain lines, same as in a building. Also, as the tank fills it forces out any gas and when it is emptied it sucks in fresh air.
I have not done much with septic systems. You are correct that they do not have an exit trap. When I first moved out of the city and built my house I put in an exit trap and got dinged by the inspector. My understanding is that you don't need or want an exit trap with a septic. You don't have huge volumes of water rushing by your house main causing a venture effect sucking out you traps and the septic tank works with anaerobic bacteria, so they don't like fresh air. Any build up of gases would be vented thru your main vent on the roof. That's my understanding but as I said I never worked on septics except my own so if some one here has more knowledge and finds a mistake, Please fell free to correct me.
Sweeney15,
Thanks, makes sense to me.
"the septic tank works with anaerobic bacteria, so they don't like fresh air."
That is the definition of "anaerobic" - FWIW
Niles
I know that and I am glad you do too.
Just to be anal about the function of the bacteria in a septic tank system. . . ;D
Anaerobic bacteria perform the first treatment of the wastewater, generating gas that is vented through the vent stack of the building's plumbing, and breaking the solids into a liquid form. The oxygen-free conditions inside the septic tank also deactivate some of the disease germs that are found in sewage.
The drainfield provides secondary treatment of the sewage by allowing aerobic (oxygen-using) bacteria to continue deactivating the disease germs that remain in the wastewater.
Surprising how much goes on in the black box after you flush. :o
I'd like to stay outside of that box. ;)
Kyle
Excellent explanation.
And I think is appropriate to be anal about septics
Niles
Sweeney and I know that and are glad you do too!
Kyle,
This brings me to another question. If anaerobic bacteria change the solids to liquid why does the septic tank need to be pumped?
And, if it does, how often - roughly?
Years ago I opened the top of my septic tank. What I found surprised me. There was a pink colored 3", tough, almost like plastic, layer on top of the liquid.
What really surprised me was the liquid underneath had no odor whatsoever?? I expected it to really stink?
Obviously all the solids aren't reduced to liquid.
Frequency of pumping out the solids varies with how it's used & what is put in it.
I've known septic systems that have lasted 20 years with no maintenance, I've also known some that don't last 2.
On the one that lasted the longest, if they didn't eat it, it didn't go in the toilet . . . .
Garbage disposers aren't good.
Harsh chemicals aren't either.
Cigarette butts & certain feminine products won't break down.
A google search can provide lots more stinking details for those who don't want to think outside the box. ;) :o ;D ::)
Ha ha I was gonna go somewhere but thought better of it!
Pink & No stink!
Only you bud, only you! :)
Ace
My mistake! Didn't read far enough! Darn phone! Now it makes more sense with Niles!
You almost had me there Kyle!
Sorry!
Ace
Kyle,
I was a little reluctant to admit it because I figured I would get a lecture but mine hasn't been pumped out in 27 years!!
However, "the one that lasted the longest" and the three things listed underneath describe our situation perfectly so maybe that is the answer.
Ace,
I think your mind is in the sewer!!
Actually it was in the black tank! ::)
Ace