Happy Wednesday All -
As I have been thinking through my HVAC setup for the bus, I am contemplating getting rid of the webasto heater. I have inherited the home made webasto setup from the PO and here is how it is currently setup:
A diesel fired scholastic webasto heater -->
Hooked to a 12v pump-->
running into a 12 gallon home style water heater-->
that runs to a "manifold", A giant home made water distribution panel. -->
There is one run up to the front of the bus to the drivers area that goes to a radiator-->
one run to a "heat exchange" toe kick style heater inside the galley-->
and one run to a heat exchanger that is connected to the engine cooling system.
The current system eats up a bunch of space under the bus and I cannot think of any really good reason to keep it.
What I have been thinking is taking the water cooling system from the diesel generator and using the heat generated from the generator it in place of the webasto. This would heat water for showers, preheat the engine and could add heat to the bus although I think we will rarely (if ever) use it for that. We are planning on having enough battery power that we would have to run the generator 2-3 hours a day if boondocking. We are currently planning most of our stays in campgrounds.
1. We will have a water heater that uses electrical, engine or generator heat (and/or propane but we are trying to stay propane free)
2. Our Mini-Splits will provide heat in the bus and this can be supplemented with heat from the generator
3. Our block heater or generator heat can be used to warm the engine on a cold start.
Each of these systems has a fail-over without the webasto and I cannot think of another reason in our system to have to rely on the webasto.
Before I make this drastic move - What do you all think? How often do you use your webasto/aqua hot?
Is there something I am missing? Will I have regrets later on?
Thanks!
-Sean
www.herdofturtles.org (http://www.herdofturtles.org)
Quote from: Seangie on September 19, 2012, 06:56:04 AMHappy Wednesday All -
As I have been thinking through my HVAC setup for the bus, I am contemplating getting rid of the webasto heater. (snip)
Thanks for starting this thread, Sean. I don't know enough to be able to help you but I'm interested in this subject. Thanks, BH NC USA
Sean,
That is a great topic. Here are my thoughts.
What about simplifying your setup so it can preheat your engine and maybe run one or two toe kick heaters. Here is why.
I forgot who it was, but at one point a family was posting on the board here. They had gotten their bus and went on a cross country trip. It was nice and warm when they left Nebraska. When they arrived in Wyoming it turned cold and snowy. Long story short they stopped for the night, and then it all broke lose. They couldn't hardly get their bus started the next morning, their heat wasn't working, the generator wouldn't start, and their air supply was frozen up. They were all cold and there wasn't any cell coverage (again, this is all from memory, so some details might be off). They finally got started and were able to leave. But, it was a very sobering reminder on a lot of fronts.
That being said, heat is one thing that I don't skimp on. We have been up in northern BC in very early spring, and we are just fine. All of our tanks and pipes in the bays have electric heaters on them (not saying that you should add those). Coldest we have been in our bus so far is -20, if I remember correctly.
I am not saying that I suggest you should be ready for really cold temps. However, I am saying that I think a way to always be able to preheat your bus so you can roll, would be good. When it is cold, if you can start it and have air pressure, you should be able to roll out of there. As always, you don't plan on getting into difficult situations, but it happens. As others can attest, I have been in blizzards in Wyoming in July. Stuff happens.
FWIW
Enjoy
John
Sounds like a good way to free up some space, I have been looking at webasto heaters, that would definately be the best for me, my kohler generator is air cooled. and propane fired, my problem is trying to find a good place to install the webasto, hopefully I can squeeze it in the engine compartment? lol
John.
John (316),
I read that post. It was a nailbiter. I can't imagine running like they did in that many hours with no heat.
Ideally - We are not planning on being anywhere the temps drop below 32 degrees for long periods of time. My wife was born and raised way down south so anything less than 80 degrees is winter to her. I've been a surfer most of my life so I am pretty weather savvy and I don't think I would ever find myself in a situation like that. Not that it couldn't happen because weather can change fast but we wouldn't be in a place that cold "through the winter". Maybe for 3 days to a week at the most. In their situation, I would have checked the weather before leaving and got a hotel room for the night or two instead of trying to beat the storm.
Your post does bring up a good point though - Auxillary heat in the bays and/or engine compartment. A good system of keeping the bays from freezing in overnight temperatures might be worth looking at. Currently we have a single 1500 watt little electric heater with a thermostat and fan on it. Not sure how well that little guy would hold up in temps 20-0 or lower. I still don't think the webasto that we have would be the best solution for that though and here is my reasoning -
It takes 1/2 gallon of fuel per hour to run the webasto, in addition to that the battery drain is heavy with the 12v pump running. So I would have to crank up the generator anyways at some point to re-charge the batteries to run the webasto. It just seems like running a 1500w heater with a thermostat and having the generator kick on when the batteries are low makes more sense than adding the webasto to the mix. And if it is cold enough that we have to run the mini-spits inside, the generator would be running anyways. If we were on shore power we would just run the electric heating fan(s) under the bus.
Keep at it though - Good stuff, keeps my brain ticking.
Quotehopefully I can squeeze it in the engine compartment
John - Here is a PDF of the installtation instructions for the style of webasto that I have-
http://www.newyorkbussales.com/pdfs/Webasto%20School%20Bus%20Heater%20manual.pdf (http://www.newyorkbussales.com/pdfs/Webasto%20School%20Bus%20Heater%20manual.pdf)
If you split up the pieces it doesn't have to take up so much space. Starting on 5-1 you can see how they recommend the setup on school buses. I have thought about re-arrainging the pieces that I have to make more space but the more I think about it, it just seems like a lot more work for something that I may never or slightly ever use.
At the end of this I may have a perfectly good webasto heater to sell you :)
-Sean
www.herdofturtles.org (http://www.herdofturtles.org)
Sean thanks for the info, I have been researching the webasto for some time this info will be a great help, and yes I would be very interested in buying your system should you decide to make the switch good luck.
John.
Hi Sean I travel to florida in late dec , the temp when we leave can be as cold as -30 f (has happened twice ) brrrrrrr .I have a heated garage for the bus so its about 60 f inside when we pull out but I use my proheat to help heat motor as at that temp I drive for about 35 min before bus temp is up to 170 f . my proheat is set up to pre heat the motor and in floor pex heat. After 1 hr I turn off the proheat. As I drive I keep the floor heat on ( now the bus heats for floor ) I turn off the rear bus fan heat as my wife hates the air it blows (to much air flow ) on her contacts as well as the noise. It was on the bus when I purchased it and installed the pex in floor for heat. works great .So my point is by chance if you need extra heat it is there . Yes you might want to refine it. Because unlike your wife the rest of us are stuck up here dealing with this cold s*!t, or you could always go out and get your self a cookie sheet and some charcoal to slide under your motor for those real cold days lol. thanks dave
This might be thread-jacking and if so, I'll move my question, but this discussion has lead me to think more about the setup on my bus, which I'm converting now.
I have a 1986 Neoplan AN440 city bus, which has an enormous radiator, as well as the AC condenser and evaporator, on the roof. The AC is shot, and at 130k BTU, way too big for my needs. So I'll be tearing that all out. But the radiator is still nice to warm the bus as a whole using engine heat.
I talked to a friend who suggested that I could add a systems similar to the Webasto to circulate and heat the coolant in this roof radiator. It occurs to me as I read the cold weather engine issues above that this could also be used to keep the engine warm. I think I have plenty of space above the engine, but I wonder if this makes sense for me? Oh, and I'm in Minnesota, so cold weather is possible at any time!
Soren
1/2 gal a hr Sean translates to 12 gals a day and that is figured on a 50% cycle in real cold weather they will cycle more than 50% of the time
AquaHot says figure 6 gal a day in normal weather even at 6 gals which I never saw one use less than 10gals a day with kids and demand hot water do the math at 4 bucks a gal for fuel
I have never been a huge fan of those fuel sucker and don't like the noise, upkeep or smell either lol
A 1500 watt heater is 5000 BTU, your Webasto is 45,000. My experience, even in North Florida and in a fairly tight and well insulated coach, is that you will need 25-30,000 on a cold night.
Personally, I would keep it and make sure I had enough battery to last the night.
At 0.4 gal/hr and a 50% duty cycle, you are not going to get more economical unless you go to propane.
Most Webasto units have 0.35 GPH nozzles. That translates to a little more than a third of a gallon per hour. So for a 24 hour period at a 50 percent duty cycle is about 8.5 gallons usage.
I once, inadvertently, left the bus off shore power for 7 days during cold winter temps. Nothing above freezing not below -5 F and windy. We used less than half a 450 amp hour battery bank per E Meter. Thermostats set at 50F inside the bus and 40F in the bays. All eight heat units were fan driven.
That facts on Webasto fuel and electrical usage.
Bill
The fuel usage of the Aquahot and Webasto (which are the same ) is about the only complaint you hear from Prevost owners even at 8.5 gals a day and having one in the past in the cold country and the mountains that used 10+ gals every day 8.5 sounds good to me but its still over 32 bucks a day and they suck when the fuel gels
We only have ours on for short bursts during the summer, when we need hot water. When we have shore power, we run off of electric. In the winter when we are rolling we can use engine heat (through the house system) to have hot water and heat. When parked, either shore power or running the heat.
Other then propane, is there a more efficient heating method?
Thanks,
John
John316, if you combine a high performance heat pump and direct some waste heat from a water cooled generator, you might be able to cobble together something that is quite a bit more efficient.
The generator could produce 10,000 BTU in electrical power (2 KW) which could power a heat pump that could produce 24,000 BTU at 5 F. With some of the waste heat from the generator heating the outdoor unit, you could extend the operation of the heat pump down well into below zero territory.
Assuming a 6 KW generator, you could add a 3 KW electric heater for an additional 15,000 BTU as backup. When you don't need the backup, you would have most of your generator capacity available for house needs.
An efficient 6 KW generator should be able to produce 3 HP which would cover 2 KW of out put for 1/4 GPH, or $1 per hour in fuel.
While I don't know anyone who has done this, I think that it is possible. At least, it's not perpetual motion!
I like the KISS theory. I don't like the Webasto, Aqua Hot systems-they're a lot of maintenance with lots of plumbing and extra pumps, etc. I also don't like propane, but have succumbed to the stove and furnace running on propane. I use two-10gal electric water heaters from HD-one plumbed into the next with the final one powered from the inverter ($550.00 for the two). Heater element for the water heaters are about $20.00. I have a 35,000btu propane furnace. New furnace is about $600.00. My engine has an electric block heater.
More than that, no extra coolant hoses running everywhere. Each hose and joint is another possible leak waiting to happen. In the 17 years this system has been in my bus, I've only had to replace the furnace once-and that's because I left it on without the propane on for 2 weeks-the fan motor didn't like that. And the new one is redesigned to be quieter. No maintenance on the water heaters except draining them when I remember to. Good Luck, TomC
Seangie/Sean in his original post said he did not like the way the Scholaslic Webasto was set up in his bay and took up too much room.
I have s Scholastic 45k btu Webasto in my RTS and it only takes up the room of the unit itself, and it is in a sound-proof container, and is the greatest heater for my conversion the way it is set up. That is the key-- you have to set it up and forget trying to copy the Aqua-Hot heat exchanger setup. You need to plumb it in just like the Scholastic Heater Manual shows, but just add the water heater in line with the engine coolant flow. If you don't need the engine pre-heat, you just shut the valves off going to the engine and your Webasto only heats the water heater and the interior of the bus. Thats cuts your Webasto run time to 1/4 of what it takes to heat the engine and interior at the same time. Very little fuel use, and you stay nice and warm without using more fuel and battery power. If you can get a 15amp, 120v power source you don't need the generator, you are have all the power you need to have a cozy, warm interior that propane or electric cannot match. With four golf cart batteries, I can run my Webasto all night without a generator. I don't use any propane heat. This is my set-up for the last 10+ years.
--Geoff
--Geoff