http://prevostmotorhomes.ning.com/forum/topics/external-tank-sensor (http://prevostmotorhomes.ning.com/forum/topics/external-tank-sensor)
Inital opinion is thumbs up on this product. price is right concept is right, went in easy, and calibrated easy, and is easy to see and understand.
Control panel was a bit fair............plastic
I like my system better-shine a light in the tank and you can see the level of the water. Simple-nothing to go wrong. Good Luck, TomC
I went for what was at the time a hi tech $$$$$ system for the holding tanks. Had to constantly tinker with it to keep it in adjustment. Display panel malfunctioned, do you really think the new improved panel fit the old opening??
Doing again I would cut a 1" wide slot in plywood box from top to bottom of tank to form a sight glass and borrow Tom's flash light to check the level!
Also I would have the vent pipe protrude into the waste tank about 3 inches. When the tank is full to the point it blocks the vent pipe the toilet will burp when you flush!!
After you full time for a while you develop a sense of when things need to be done and seldom need to check. Except when filling the freshwater tank, but then you are outside filling the tank and the fancy high tech $$$$$ gauge is inside!! HTH JIm
of course above will not work with SS or aluminum, blue plastic drums, black PVC tanks salvaged from RV's etc
How exactly do these external sensors work? I've googled "Series tank systems monitor" but haven't found the product or manufacturer.
I've already bought a traditional monitoring system for may tanks that uses copper contacts inside the tanks - supposeably good for any type of liquid including sewage - but I have read a number of comments about such systems being unreliable. I'm afraid comments such as "my system is better - just use a flash light!" don't impress those of us who have tanks that cannot easily be accessed (in my case the tanks aren't inside the bus, or even in a bay).
Jeremy
Certainly a big advantage in having the toilet mounted straight over the black tank with a straight drop.
None of my tanks have sensors and since we fulltime in the bus, we have a pretty good idea of how long we can go between fills/empties.
So there you have it.
General concensus is a waste of time and money.
Sorry for wasting your time with the info and photos of a plumbing bay on a Marathon that do that perticular aspect of a conversion probably betteer than most current converters.
I'm an ex trucker I guess I was a moran enjoing the function of the fuel guage should a broke off a stick.
Deep Breath!!!! opinions will be rendered rite or wrong..keep posting and I should have had stick when fuel guage failed on I-65 and it cost me 185$ for 5 gal of fuel HA Ha. one person that read or will read might be making the sensor decision now. Bob
Jeremy, check Snake River Electronics for info all the converters and s&s guys in the Oregon area use it been around for years
good luck
don't be so touchie joe. ;). you'll find a bunch of people like to keep it simple, and some like to make it as complex as possible, with lots of bells and whistles. i'd be happy if it just worked, but some folks would string xmas lites around a sign that said "tank full" because they can.
i was trying to blow up the photo so i could see the manufacturer's name. we have sensors inside that work after i thoroughly rinse out the tanks. but the next time i drive and swish around the contents, the tank reads full. :(. and by the way, we did just confirm how long it takes to fill the black tank to the top when the methane smell started invading the living area. i thought we had another day or 2. oops.
so i'd be interested in finding a way for accurate tank readings at a reasonable cost, and maybe using the wires already there.
Quote from: luvrbus on October 20, 2010, 06:06:58 AM
Jeremy, check Snake River Electronics for info all the converters and s&s guys in the Oregon area use it been around for years
good luck
Thanks. I see that they say the sensors work on 'any plastic or fibreglass tank', and they also have an internal version of their 'external' sensor, for use where you can access the top of the tank but not the side:
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fwww.ddoem.com%2FSnake_River_Electronics%2Fimages%2FS_MODA_Rod.jpg&hash=5a8c00c4d839a0d8fcde3f0972749cf283cfa54b)
Jeremy
Joe, first of all, thanks for posting about an issue that has been a long time problem. Please do not take offense at a discussion of what others do to get the same information. I think this could be a great thread on how to address the problem. Your solution sounds like a good approach. I have read in the past that outside sensors can also have long-term problems when the inside of the tank gets coated. I hope you will give us a long term use update.
There are not many metal holding tanks any more, but I don't think that system would work on metal tanks.
Like others, I have plastic tanks where I can see the fluid level. I also have valves at the bottom of the gray and fresh tank that are connected to clear plastic tubing. The tubing is connected between the ball valve at the bottom and a fitting at the top of the tank. When I open the valve, I get a visual reading. Works good on the fresh water tank, but the tubing for the gray tank gets coated and it hard to see. My black tank is 85 gallons, so I don't worry about its level. BTW, I use the same clear tubing measuring system on my auxiliary diesel tank (use fuel grade red tubing - not easy to find).
Tank level sensing has been a problem since the beginning. I have never heard of an inside the tank system that worked for the long run. The black tank environment kills any sensor that is inside the tank - at least that is what seems to be the preponderance of information.
As I said, I have heard mixed reviews of sensors mounted on the exterior of the tank.
There are two other technologies that folks are playing with. The first is a pressure gauge mounted in the bottom of the tank (measuring head pressure - thus the height of the fluid in the tank) and the second is a sonar type approach where the sensor is mounted in the top of the tank and "ping" time measures the level.
Silverleaf has a very expensive module for each type of system that can be tied in with their "house" monitoring system. I don't think they would work as stand alone systems. They use the pressure sensors for the fresh/gray/black tanks and the sonar system for the fuel tank. I don't have any first hand experience with these units.
All of this presented is the spirit of open discussion and should not be considered a dis on the system that Joe has installed!
Jim
Joe,
I have the same system on mine, been there about 4 years with no issues.
Though I do have the older model of control panel.
Mine are on plastic tanks.
Cliff
Although my system is not made by the same people, it is basically identical. It has sensors mounted on the outside of the tank. I have had it in place for 20 years and it still works fine. Also has a connection for the LP and a battery monitor(of sorts) Its called an AccuGauge and oddly enough, the installation manual is sitting right here on my desk(can't remember why though)
But I do use the peer-thru-the plastic side_ method ---when I'm filling the fresh water tank. And the "full indicator" is water gushing out the filler.
There are (or where?) a number of manufacturers making similiar systems with sensors that stick on the outside of the tank. Centroid Products (www.centroidproducts.com (http://www.centroidproducts.com)) makes senders that go into a water tank, but they don't work with waste water. They even make a display if you need one.
I had intended to get one of the systems with the stick-on sensors, but I decided for my use that looking at the tank level works just as well. If I used my bus a lot more I would get one of these systems.
I once had an old motorhome that I put a similar system on. It worked fine. Recently, after noticing that my tanks already had sensor probes in them, I installed one of the standard units. The fresh water works as it should, but the black tanks shows waste in it even after dumping. That's okay. The idea is to get a quick convenient read on it. If I know that I just dumped, I know it's empty. The only thing I'm interested in is when the full light goes on. If in doubt, I can always do the flashlight thing. Strangely enough, having sensors does not limit your ability to look at the tank directly. In short, even if it is not perfect, it is a great convenience and relatively simple to install.
I have a system made by Garnet. It's a circuit board that mounts on the outside of the tank and it reads in 1% increments. Works very good, I would buy again. The remote panel has a readout for battery, fresh, grey, black water and LPG. Good Busin' Wilbur
Quote from: Jeremy on October 20, 2010, 02:37:40 AMHow exactly do these external sensors work? I've Googled "Series tank systems monitor" but haven't found the product or manufacturer. I've already bought a traditional monitoring system for may tanks that uses copper contacts inside the tanks - supposedly good for any type of liquid including sewage - but I have read a number of comments about such systems being unreliable. I'm afraid comments such as "my system is better - just use a flash light!" don't impress those of us who have tanks that cannot easily be accessed (in my case the tanks aren't inside the bus, or even in a bay). Jeremy
Basically every material has a characteristic called
capacitance.
("Rough" explanation for the non-electrically aligned:) This is an effect that a material will resist a change in the voltage across it at low frequencies - which it does by absorbing charge if the attached circuit has more voltage than the material, and releasing charge if the attached circuit has less voltage than the material. This effect if for a unit of measurement of the material - for instance say a piece of plastic tank 1/8"-cubed has a capacitance of 40pF (that's pico-Farads, "Farads" being the unit of measurement used for capacitance - pico meaning 0.000000001 Farads). If you increased the volume of plastic to 1/8"x1/8"x1/4" you have doubled the volume and also the capacitance (so now you'd have 80pF). If you recall I stated that capacitors resist change, well more capacitance = more resistance to change. What you can do is alternate the voltage field across the material and watch how long it takes for the material to balance out with the circuit.
Again, all materials have a capacitance value - even people. If you've ever used one of those cool lamps that you simply touch the plastic base and it turns on - you've seen this effect. Your body adds so much capacitance to the circuit, that it takes a lot longer to balance out - a very simple circuit can set a switch point where you can say "pushed" or "not-pushed" based on the value - or in the case of a sender, you can build a circuit that reads how long it takes to balance out the circuit and refer to a calibrated Look-up-Table or equation to provide a human-usable value. Even water and poo have capacitance values, and the more you add to a tank the more time it takes to balance out the circuit – so with a micro-processor you can tell when there is no water/poo or it is full of it, and show that on a display. By the way, with a very high resolution grid on an LCD display, you can tell how far away from the screen a finger is or where on the screen a finger or multiple fingers are. This is the technology that Apple uses in its "iPod Touch" and iPhone touch screens.
As to your inquiry about the "my system is better than yours" not being good enough - since capacitive sensors are external (mostly, there are some like the Centronics fuel tank sensor that are internal) they don't get in contact with the material being read, so they are less likely to rust. Also, since there are no moving parts, they aren't as likely to break (plus being external they don't take up tank volume, which could get you an extra flush in a crisis :) ). True, they can be affected by build-up in the tank - but that is a simple matter of maintenance - you either clean the tank to get back your original tank volume or you recallibrate (if you are truly lazy). Since they don't require that you poke a hole in the tank to install it, they are also less likely to leak, or become a weak spot in cold weather.
A while back, we had a discussion about a Centroid type fuel sender and I had put u a link to an electronics article that showed how to build one of these yourself. You can find that thread here (http://www.busconversions.com/bbs/index.php?topic=11857.msg124264#msg124264)
-Tim
Thanks for taking the time to explaine that Tim.
I just cut and pasted the entire paragraph.
I hope you know what you are talking about LOL