Is this furnace adequate for a mid-size bus?

roach711 · 09-27-2010, 12:09 PM

I'm planning to convert a mid-size school bus (6 to 8 windows) or a larger shuttle bus in the near future and have the chance to buy a new Atwood 16,000btu Everest Star unit (7916-II) at a very good price.

Our intended use for the bus will be fair weather rv'ing but some Michigan winter outings certainly aren't out of the question. So my question is, is the unit going to be big enough for cold weather use in a mid-size, insulated bus?

Thanx - Rick

RevBill · 09-28-2010, 05:49 PM

Good question .. I have been eye-balling these and wondering the same .. this is the generic info on them ..

The dependable Everest Star II series builds on the 20-year success story of its predecessor with improvements such as: an electric shut-off on the gas valve, the new blower assembly that increases air delivery by 60%, and electronic ignition (no standing pilot).
Weighing in at just 23 pounds, the Everest Star II #36545 can produce 16,000 BTU’s per hour of input heat. The compactness of the furnace optimizes space utilization and furnace placement flexibility. It offers three different vent kits for cabinet depths ranging from 20-1/2" (524mm) up to 31-1/8" (813mm). It can be configured for front discharge only, discharge from both side ducts, or a combination of front and side ducts.
Specifications:
Ignition: Electronic
Voltage: 12 VDC
Current Draw: 3.4 Amps
Energy Source: LP
BTU's: 16,000
Cutout Size: 8-3/8" x 11-1/4"
Furnace Dimensions: 20-1/2" (L) x 8-3/8" (W) x 11-3/8" (H)

(Edit)

edited my edited edit .. dangit .. wow .. tougher question than I thought .. heat-loss ratios and such ..

roach711 · 09-29-2010, 11:52 AM

Thanx for the info Bill. As you found out, there's lots of technical info on the unit but no real-world advice on what it will heat. I tried an experiment with a small 1500 watt milkhouse electric heater in a room about the size of a small bus and it did warm up the room. I found a conversion from watts to BTU's and the 1500 watt electric heater is the equivilent of 5100 btu's. I think 3 of my little heaters would have warmed up the room quite nicely so the 16,000 btu furnace is likely to do the job.

Anyway, the question is academic as I went ahead and bought the thing last night. When I get it I'll hook it up in my garage and see how it performs.

RevBill · 09-29-2010, 05:49 PM

.. well .. lol .. stayed up until the wee hours last night (this morning) .. I did find one site (again, for houses) that would let you pick the "region" you lived in and used 300 sq ft (which should be larger than a mid-size) and that 16,000 btu unit was WAY more than enough even if you lived in Canada .. in fact, at 300 sq ft a 10,000 btu unit was good for most of the USA ..

.. you're right, it is all very subjective until you "put your arse to the mill" as my Grand Dad used to say .. my only real-world experience is with an old live-aboard sailboat I had many years ago, and I didn't have nearly so high-tech a heater .. I know it was much harder to stay warm and cozy in the Atlantic than it was in the Gulf (that dang heat-loss due to outside temp and a concrete hull .. yes .. concrete .. she was a kewl boat ..) ..

.. I am really curious to know how much fuel that little monster uses per hour to maintain a 73-75 degree temp in say a mid-40's to low 50's outside temp with a reasonable R-value .. please keep us updated with your progress .. I really like the info on these little units ..

lornaschinske · 09-29-2010, 07:11 PM

We have an RV furnace in the Class C. 22 ft of "not much" insulation (1 1/2 inch thick foamboard in the floor, 2" in the walls & ceiling). We keep the windows covered with Reflectix & Foamboard in the winter (also the summer here in NM). For a Southern Appalachian winter (TN & NC) our old Suburban LP furnace kept us plenty warm (I don't care for being cold... and I don't like snow). It did not suck LP like I have heard others say they do. We did supplement with electric heaters at times (not as much in NC since we were paying for the electric) and we dropped temps at night since we had a heated mattress pad on the bed. But running strictly on the furnace, we would heat & cook on 20lbs LP every two weeks from Nov 2008 to March 2009 in NC. Our water heater (LP/AC) was on AC during that time. I think our Furnace is rated at 12K BTU... it may be less and certainly not more.

opus · 09-29-2010, 08:13 PM

So I have 3-80,000 btu heaters, a 90,000 one and a 30,000 one. I should stay warm one would think.

roach711 · 09-30-2010, 08:49 AM

Dang, Opus! Are you driving your whole house around? Or are those what you have available?

Thanx guys! I'm thinking the 16k unit may be a bit oversized for my application but if it is I can sell this unit at a decent profit and get a smaller one. For the amount of time we'll be using it in cold weather (minimal) I don't imagine a slightly-too-big one will be a problem.

Bill - you're a man after me own heart. Research!

Smitty - Good point about the effiency loss on gas heaters. My electric heater has no "stack loss" so actual output BTUs would be higher.

One thing I noticed is that 12k BTU's is about the smallest heater commonly available and those are recommended for popups and small campers. A popup would have god-awful heat loss numbers, for sure, but they're small. Adequate insulation and good weathersealing would make a big difference.

Anyway, I don't have a bus yet, so it will be a while until I get to do a real-world test. I'll surely post the results when I do.

opus · 09-30-2010, 09:03 AM

Quote:

Originally Posted by roach711

Dang, Opus! Are you driving your whole house around? Or are those what you have available?

Those are the heaters that came with it.

lornaschinske · 09-30-2010, 09:59 AM

For the bus, we plan on keeping the original heaters that came with it (with a few modifications) and include a small BlueFlame or Radient LP wall mount unit (it goes "in" my fireplace mantle). We acquired a used LP water heater off CraigsList that we have decided to use to heat the coolant for the bus heaters. We got them so why not use them. Be silly to buy basically the same thing. With a couple of by pass valves, we can use the engine to heat the bus over the road the "water" heater setup to preheat the diesel engine if we should find ourselves in cold weather and needing to go. I might put a tiny CAT heater in the bathroom area if I can find the wall space to do it... It seems to get kinda cool out here at night!

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