Propane furnace data & test results

DavidInWilmNC · January 31, 2008, 12:43:07 PM

John,

Ideally, I would have hydronic heat. It's taking me so long to get the basic systems going that I can't imagine trying to add one more system to the mix. I currently have a hot air diesel heater which works fine (30K BTU's), but I'm thinking I'd like something a little more mainstream like a standard furnace. The good thing is that adding hydronic heat to the bus later won't be all that complicated; perhaps it'll be in the budget then, too!

So far this year, I've managed to get by with a 15K BTU heat pump and a 10K BTU portable propane heater, but my bus is still in the construction stage. I'm not really planning on being without a power pole too much in the winter. Thanks for all the points, though.

David

JohnEd · January 31, 2008, 02:10:48 PM

David,

I am in complete sympathy you, believe me. A quote "enuf is enuf but too much is plenty".

I like you oil fired hot air system because I know in my heart of hearts that diesel oil fired can be translated into WASTE ENGINE OIL fired and that is free fuel. Has to be a way. 30K BTU will keep it hot after you insulate it and install more thermally efficient glass for sure. Only draw back is that it might take a while to get up to temp after a cold soak. Is you system a used military version, or a commercial?

I am impressed with what you have been able to accomplish up there.

John

DavidInWilmNC · January 31, 2008, 08:43:35 PM

John,

It's a military heater. It's actually pretty neat once I figured out how it works. I'm also glad you reminded me about waste oil... I'd forgotten about that. WVO is also an option with a bit more work. Maybe I'll keep this one and install a propane furnace as well. For some reason, I won't feel safe leaving this diesel furnace on automatic (when I get an automatic thermostatic control assembled) to keep the bus around 40 or so to avoid freezing. Maybe I'll feel better about it when I get the thermostat control and the unit installed!

David

Quote from: JohnEd on January 31, 2008, 02:10:48 PM
David,

I am in complete sympathy you, believe me. A quote "enuf is enuf but too much is plenty".

I like you oil fired hot air system because I know in my heart of hearts that diesel oil fired can be translated into WASTE ENGINE OIL fired and that is free fuel. Has to be a way. 30K BTU will keep it hot after you insulate it and install more thermally efficient glass for sure. Only draw back is that it might take a while to get up to temp after a cold soak. Is you system a used military version, or a commercial?

I am impressed with what you have been able to accomplish up there.

John

Hartley · February 01, 2008, 12:37:56 PM

I have a 35k furnace in my bus, It's under the counterin the kitchen.

I didn't have the option when I stuck the kitchen together to run the hoses because I wasn't done, Now I am stuck because I have to live in the bus and can't start moving stuff right now.

So, I leave the cover loose so all the heat blows directly out of the furnace. The kitchen is toasty as is the hallway. I have a heater-buddy up front that sits by the step and a heat strip back in the a/c unit in the bedroom. and a ceramic heater back there also when it gets really cold.

So far I have survived 7 degrees a couple of times. Had ice form on window frames inside and all that. I think this summer I will address the insulation problem a little closer.

Oh... LP gas prices just took a BIG jump... my 20 lb now takes $18 to fill.
My 100 lb went from $55 to $68 to fill. And that's just since last month.

Dave...

John Z · February 01, 2008, 03:40:55 PM

I filled my 2 new 50 pound tanks on 1/19. One cost 28.50 and the other was 29.00. They were brand new tanks and needed to be purged. Seems he said it was 2.50 a gallon.

gus · February 01, 2008, 07:25:38 PM

As nusa says any fabric or wood will absorb very little if any heat so they both help in heating the bus, especially if the fabric is covering windows.

The sun is the cheapest heat you can get, especially on Al which absorbes it really fast. No mystery there.

Double windows are much better than single but are still one of the biggest heat losers in the bus along with anything metal that is not completely insulated.

Some of my windows are painted black inside and are effective heaters in sunshine - nice in cold weather but awful in hot!

Needless to say all heating ducts should be at floor level, they aren't much use coming from the ceiling unless they blow straight down.

JohnEd · February 01, 2008, 08:30:22 PM

Dave,

Place a "small" 6 or 8 inch house fan on the floor blowing straight up towards the ceiling in the area near the furnace. The entire bus will be more comfy and maybe even your back room will take on a different temp behavior. I have done this in every S7S and home I have had or lived in. It is really great in the winter for getting your feet warm....anywhere in the house. $12 fan at Wallmart. Lots a bang for the buck in comfort and a little reduction in fuel usage.

When i build my bus I will integrate this warm air destratification device into my cabnets somewhere.

That stairwell needs covered.

buswarrior · February 02, 2008, 01:12:24 PM

Excellent work Chuck!!!

The exercise also suggests the speed/energy issue.

If you do not plan to let the coach cool off, then spec your furnace according to the traditional thoughts regarding efficient operation and proper cycling.

If your use of the coach demands a faster warm up from cold, (or cool down from hot, it goes both ways) then big BTU is your design need.

Rv's are notoriously under spec'd for cold weather operation, as price point and lowest common denominator are the motivators.

The strategy of redundant methods to reach your needed BTU is also a good design goal. When one of those heat makers fails, you have alternatives.

This leads to the major reason for failed execution and unhappiness in mobile command centres/emergency responce vehicles based on RV specs. Way too little heating and air conditioning for a vehicle left parked somewhere for weeks/months at a time, and which is likely to see the doors open continuously.
And waiting hours for it to warm up, or cool down, when the on-scene folks are already frozen or cooked upon its second tier arrival...

I, too, like the quote: "enuf is enuf but too much is plenty".

Just like the outhouse tank, you only hear folks complain about too little, never about too much.

100 000 BTU at the ready...

happy coaching!
buswarrior

DavidInWilmNC · February 02, 2008, 04:16:25 PM

Quote from: DrDave-Reloaded on February 01, 2008, 12:37:56 PM
20 lb now takes $18 to fill.
My 100 lb went from $55 to $68 to fill. And that's just since last month.

I just had a 20 filled yesterday... it was a bit over $14 with tax. As best as I can remember, a 20 cost $12 and some change (plus tax) a year and a half ago. Where are you getting your tank filled? I get mine filled at the local LP gas supplier, and it's truly local (about 5 blocks away). At any rate, I can't believe that any fuel here in Wilmington is actually cheaper than elsewhere ('cept for the West Coast).

David