More efficient propane furnace

howardwheeler wrote:
I have a fair-sized fifth wheel and am often surprised at both the propane usage and 12v power the furnace consumes. It is 18 years old but works good and is clean (no dirt dauber nests and so on). Has anyone come out with a more efficient furnace that big over the years? I can live with this one but it sure would be nice to have a more efficient unit.

Do you use it boondocking, or just for general heat? The heat exchanger in the current gas furnaces, really doesn't have a great design. Your beat bet might be a vented catalytic heater.

As mentioned earlier in this tread; a big part of the equation is the lack of insulation in the average RV. The average home has at R values of at least 6 in walls and 13 in the ceiling and HVAC ducts are insulated. Most RVs have little if any insulation in walls and ceiling and none on the undersized duct work.

I swapped out my power and amps ‘sucking’ OEM Suburban 30k btu, for a Atwood 2 speed 15-30k btu furnace which once achieving 2 degrees of the t-stat set-point it shifts to low burner and low speed mode, and remains there thereafter… To make this swap work requires one additional t-stat wire (for the 2 speeds), and because Atwood exterior panel is a bit smaller (but sold optional), to re-use the exterior OEM Suburban access panel - this, simply done by merely lining up the furnace exhaust port with the Suburban panel’s exhaust opening and by using HVAC tape, sealing around the (slightly undersized) furnace’s parameter…Savings of both LPG and battery power is quite substantial..Amps dropped from just over 10a to about 4a…

3 tons

prichardson wrote:
As mentioned earlier in this tread; a big part of the equation is the lack of insulation in the average RV. The average home has at R values of at least 6 in walls and 13 in the ceiling and HVAC ducts are insulated. Most RVs have little if any insulation in walls and ceiling and none on the undersized duct work.

RVs probably have that much r value. In general, homes are MUCH higher. Idk where you got those numbers. Maybe 1930s insulation?

What is the two speed model number? And yes, my concern is when I boondock.

prichardson wrote:
As mentioned earlier in this tread; a big part of the equation is the lack of insulation in the average RV. The average home has at R values of at least 6 in walls and 13 in the ceiling and HVAC ducts are insulated. Most RVs have little if any insulation in walls and ceiling and none on the undersized duct work.

Modern sticks and bricks homes built after the 1930s will most likely have 2x4 walls with fiberglass insulation with at a min of R11, in the 1990s or so fiberglass insulation manufacturers came out with an improved R value of R13 for 2x4 construction..

Modern day homes ceiling and roofing R value should be at R38 or higher.

Compare that to a RV with 1x2 wall framing the insulation in the walls will be R2 or a bit less and if you are lucky R6 in the middle of your roof and R2 at the ends of the roof.. Then consider that your RV floor will have at best R2 in insulation..

Sticks and bricks homes are built with double pane glass windows, typical RVs use single pane for a zero insulation value..

You can basically call a RV nothing more than a cardboard box and you are trying to heat not only the contents of the box but the air surrounding your RV.

It is what it is, if you are planning to camp in cold weather, plan to use a lot of propane.

pianotuna wrote:


I will not use an unvented combustion heater. My daughter is a CO survivor.

Thank you for your honesty, it is refreshing.

Glad your daughter survived!

Sadly, there are a lot of macho men on this forum that take the unnecessary risks in order to save a couple of bucks in propane that believe it won't happen to them. While one can take the math behind their reasoning as to why it is justified as safe, it only takes one slight deviation in that math that can foul up the process and create incomplete combustion.

Slight deviations like elevation (lower oxygen levels to start with), contaminants in the propane (butane is often mixed in with propane depending on where you live), contaminants on/in and condition of the catalytic materials all can contribute to less than stellar combustion and that results in CO..

RVs unlike a sticks and brick home are a small confined space, much less air to dilute unwanted combustion by-products. Takes far less time for things to go sideways and when it does, one may not have enough time to realize and react.

pianotuna wrote:


I will not use an unvented combustion heater. My daughter is a CO survivor.

Please elaborate.

Was a functional CO detector present?

Gdetrailer wrote:
Sadly, there are a lot of macho men on this forum that take the unnecessary risks in order to save a couple of bucks in propane that believe it won't happen to them.

There are also a lot of men and women who understand how unvented catalytic heaters work, and how to use them safely.

I know my camper isn’t insulated like a house, but the furnaces in RVs seem unusually inefficient, even crude. It does seem like someone would improve on what is essentially thirty year old technology. My unit is in fact 18 years old. And it was no state of the art furnace when new. Someone mentioned a two stage unit. That sounds very interesting. A better heat exchanger seems possible. I know two stage units in houses do have greater efficiency. Anyway, every time I get home from boondocking I complain to myself and just thought I’d share my complaint. Does anyone know someone who makes a two stage furnace?

Aha! I found it. An Atwood Excalibur. I’m going to look into it. Thanks.