Bus heating system

[Lee Bradley]

One more piece bought for the bus. The heart of the heating system a Webasto DBW 2020 24 volt 80,000 b.t.u. diesel fired heater. My question is can/should I add a 50 gallon reservoir tank to reduce the cycles with longer burn times. Photos at ebay http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120177078252

[DrivingMissLazy]

Lee, sounds great. I had a 40,000 btu unit and it kept the coach comfy down to 0 with no problem.

With that big a unit I would think an auxiliary tank would be a great idea, otherwise it will be cycling quite often I believe.

Might want to consider a loop into the engine also for cold starts.

[Lee Bradley]

Thanks. I am planning on a loop to the engine both for heating the engine and using engine heat in the system.

[Chaz]

Great buy Lee!!! I need to keep my eyes peeled for one.
  I think an auxilary tank would be the hot ticket also. Maybe even a loop to somewhat heat the fresh water in your bus in the winter.
    Justa thought,
       Chaz

[Lee Bradley]

I did not plan on that brand or size but the price was right.
Do you mean a loop as freeze protection or to heat the potable water? I plan on installing this system in the rear bay; it should keep the rest of the bays above freezing even skiing Jackson Hole. Now I'm looking for a deal like you got on your invertor.

[Chaz]

I did not plan on that brand or size but the price was right.

That is ALWAYS a good deciding factor for me also!  The invertor was a good deal. I'm very happy I got it then as I would not be able to afford it now.

As far as a loop thru the potable water, yeah, some sort of line thru there to keep it from freezing, but i was also thinking in the winter when you need to use the Webasto, heating the potable up to say 70* or maybe even a bit more would be nice. Cold water -to me- sucks most any time, but especially in the winter!!
How to go about it........well....... I'd have to do a bit of thinking, but I'm sure it could be done.

  Good luck!!!
      Chaz

[buswarrior]

Hello Lee.

Do you expect the Webasto to keep the other bays warm by convection or by routing pipes?

My DBW300 is in the centre bay and will NOT keep the other bays from freezing by simple convection.

Too much surface area to the outside, doors, and floors, and the Webasto Bay is vented.

Now, if you are insulating and boxing in....

happy coaching!
buswarrior

[Lee Bradley]

Thanks! That is good first hand information I can use. So maybe a small heater/fan with a thermostat to keep them at 40 or 50 degrees.

[DrivingMissLazy]

I had a heater in the bay for the water system. It was a piece of copper line with fins about two inches square and about one half an inch apart. All the hot water from the Webasto ran thru this and it provided enough heat to keep the fresh, grey and black tanks, as well as the pump and filter, in temperatures down to zero. I really do not know how much lower I could have gone, but it the compartment doors are sealed fairly good, I suspect you could go even lower. No thermostat or fan required.

My cold water heater was built to accept a heat exchanger which was about three inches in diameter and about six inches long. Seldom, if ever did I have to run the electric heater in the cold water tank. Engine coolant also circulated thru this system.

The genset was also kept warm by the Webasto and/or the engine, so it was always easy to start.

The complete heating system used engine coolant and circulated it as required. It was really a very  nice system.

Richard

[buswarrior]

Many report good results with lining the floor with the syrofoam of your choice, topped with plywood, acts both as a temperature and a sound insulator for road noise.

The water tanks need to be insulated/closed in somewhat. The bay doors offer nothing but a giant heatsink by themselves.

Popularly, I've seen folks rig it up that the insulating panel is removeable, all plumbing is behind/inside and the "wall" is mounted just inside the bay door. It will pull out to access for maintenance, or for warm weather running.

I will be adding a loop from the Webasto with some pieces of finned rads inside the tank box.

It has also been frequently suggested that a water bed mattress heater placed under the tanks gives you some electric back-up.

happy coaching!
buswarrior

[Lee Bradley]

Richard,
Sounds like a good system. Do you remember how much diesel you used in zero weather?

Thanks,
Lee

[Chaz]

Lee,
  I don't recall what kind of luxury liner you run, but speaking of insulating............ I was thinking about doing something, well, maybe stupid. (WHO? ME???!!!)
  My 4108 has, for lack of a better word, a corrugated type floor. I was thinking about filling the voids with foam expanding insulation. Now, that would only do basically half the floor, but I was also thinking about filling the outside (or bottom) corrugations with foam also. (wax paper over plywood, etc.) I "think" that would do a decent job of insulating and when the bottom is coated would "slick off" the bottom for possibly less "drag".
  My demented mind is always "on". 
     Chaz

[Jerry Liebler]

Chaz,
    Your plan for the bay floors will have truly negligible insulating effect.  The floors and ribs are aluminum which is such a good conductor of heat that the insulation will be completely bypassed by conduction through the aluminum.  A much better idea is simply lay a sheet of good insulating foam over the floor and top that with a sheet of say 3/8 plywood.  The floor probably isn't the most significant heat loss site though, the bay doors are likely going to conduct more heat out of a bay.  My answer is no fresh water tanks or plumbing below the floor, all above the floor in the insulated & heated passenger area, coupled with lots of water softener salt in the waste tank, which is in the rear bay, for the winter.
Regards
Jerry 4107 1120

[captain ron]

I was told I didn't need a tank as I am running mine through my whole system. Engine heat etc.

[DrivingMissLazy]

I was told I didn't need a tank as I am running mine through my whole system. Engine heat etc.

What is the btu of your furnace? With 80,000 btu I would suspect very short cycles as it is hard to get that much heat out of the unit quickly.
Richard