Installing suburban propane furnace

[Oregonconversion]

I am trying to pick out the best propane furnace for the front of my bus needs for the living room soon and been doing a lot of research. I have narrowed it down to a 19K, 20K, or 25K BTU furnace for the front and one for the back as well. I live in an area that in the winter it only gets down to 40 F on average but will get down to 35 and 30 on occasion. I also have three tow kick heaters installed (one in living room, one in bathroom, and one in bedroom) and a big buddy for when it gets colder and I need the extra help.

Or will a 40K use less propane because it warms up the bus quicker?

I am just looking for something that is going to be not too expensive to buy and will use less propane than other furnaces. Is that possible? Or is it just amp draw I should be looking at to determine the purchase?



I have chosen suburban because of the small size of the outside holes I have to put in my rig. Seems all the others you need a huge hole in the side of your bus.

I would like direct flow from the furnace into the room as well as the option duct for the other side of the room as well.
Is there a technical term for that? ducted and direct venting model?

[artvonne]

  After 30 years of experience with them, I would like to have a dollar for every time one gave me trouble. They have far and away caused me more grief and cost more money in repairs than any other appliance in any RV Ive ever owned. Thats after considering they are noisy battery killing gas hogs. I think id rather heat with wood, at least you can get heat out of that.

[Oregonconversion]

I have thought about using a wood stove. But they are just so big.

[bevans6]

My two suburbans have been flawless so far, but I can understand the attitude of others - they are pretty mechanical devices with lots of parts to fail.  A lot depends on how you install it.  I believe the best way is to install it inside the living space they way they are designed to be installed.  Mine is in a bay, and I think that I lose a lot by ducting the heat in the cold bay, and working out the cold air return was a total PITA.  I'd go bigger than smaller, around 25K sounds about right for half a bus.

Brian

[white-eagle]

9.5a for the 40,000, 5.5a for the 30,000. suburbans.  looks like pretty good draw.  Don't know what the wabasto heats draw.  if you think wood is too big, you might look at the diesel dickerson's BW mentioned in my boondocking heat questions a few days back on that thread.
i'm looking at propane also.  
But the big question is what is most efficient?  wabasto or propane?

[Oregonconversion]

I am looking at the NT-20SQ. It looks like it only has a 3.1 amp draw and is 19K BTU. I plan on mounting it under the bar island in my kitchen.

[artvonne]

  Id have to go out and look, and if I have to pull the panel to get to it I might as well pull it out (because its "down", again). Not today. But IIRC  its either 30 or 35K BTU input, 20K output. Whatever it is/was, thats about as poor of efficiency as you can get. And its noisy.

  I miss those old gravity heat RV furnaces. They sure didnt take up much space, and they were awful quiet.

 

   

[skihor]

Don't let them scare you away from the Surburban. I had to replace the "board" in one from 1983 once. I have a 40 K in front and a 20 K in the rear. Both have been running for 8 years now with no trouble. We live full time in Colorado and in the winter see ALOT of use. We now live inside of a warehouse and heat with 1 small electric heater. Big amp draw but with 2 6V golf cart batts we can run forever on a couple hours a day Generator use to recharge.

Don & Sheila

[Oregonconversion]

The 40K furnace says it only takes 1.5 amp draw. Is that right? Seems too good to be true.
Would this model take less propane to keep my front area a constant 68?

http://www.rvcomfort.com/suburban/products/nt_high.php

[bevans6]

The linked unit is a 120 volt unit.  Most are set up for 12 volt DC, hence the higher amperage draw.  I would suspect a 40 Kbtu unit would use about the same amount of propane as a 25 Kbtu unit when operating at a low duty cycle, that is when they both can easily supply enough heat.  It might run for short periods of time and use less electricity.  But you'd really have to study it to figure out exactly what it's going to do for you.  I do one of two things - I live with what the previous guy installed or I copy an installation that someone else did that I know works well.  For example, the aforementioned 20K un the back and 40 K in the front is actually fairly common.  I have a 35K in the middle, but it is a little under powered for a whole 35 ft bus.

Brian

[Len Silva]

Whatever you decide to do, plan ahead and make it easily accessible.  I have spent several hours just taking things apart so that I could get to the furnace.

[TomC]

Propane heat is the cheapest type of heat.  The actual furnace is around $500.00 (compared to a Webasto of around $1,500), are reliable (my first one lasted 15 years until I left it on with the propane off for 2 weeks-fan motor didn't like that), but are a bit noisy.  I'm using the Suburban (rather then Atwood) because of the small exterior vent.  Good Luck, TomC

[skihor]

Make sure you have large enough return air source, and that your outlets are far enough away from it per Surburban's recomendations. Use ALL of the outlets. Also try to make your outlets simular length. The longer the run = less air flow. (The shortest run puts out the most air). Put a propane shut-off @ the unit. Makes it much easier to service the unit without having to shut down the whole system. If you haven't purchased the unit yet call Laurelhurst Heating & Air conditioning in Portland, Oregon, (503-236-2679) and talk to "ED" he often has "scratch & dent" units or Near new refurbished ones for way less than retail. I got a 40 K for $225 + shipping a couple of years ago.

Don & Sheila

[pvcces]

Here are a couple of points to consider regarding efficiency and Suburban furnaces.

The ones that I have checked out are designed to have 75 % efficiency. To accomplish that in such a small furnace requires that they use quite a bit of fan power.

The largest furnaces use the least fan power. There are slim models available, but they use more fan power and make more noise than the larger units.

The BTU ratings are based on fuel input. So, a 40,000 BTU furnace will give you 30,000 BTU output or just a bit less than 6 portable electric heaters. Most of these are 1,500 watts, which is around 5,100 BTU.

We opted for a 30,000 BTU furnace, full size. It gives us all the heat that we need. We have a backup furnace in the rear bay, but only use that if we are concerned about freezing in that bay.

Good luck with your furnace choice.

Tom Caffrey

[Oregonconversion]

So I think I am going to go with one NT-20SEQ in the front and one in the back.

Even with 2 running at the same time should be less than 6 amps @ 12V I like that!

19,000
9 1/2"
9 3/8"
21 1/8"
12 VDC
2.7
27 lbs.
22 lbs