Exhust vent for furnace on 3400RL

[Marc Morgan]

I am a new owner of a 3400RL. We are inetersted in winter camping so we are using our furnace. What bothers me is the amount of heat that is exhausted out the outside of the camper ( cover has the word "HOT" stamped it). Why so much heat going to the outside thru that exhaust pipe. Seems it should be going inside. Can anyone explain this to me.

Thanks
Marc

[jimcol]

Marc, It is not a high efficency furnace. The exhaust is coming right off the heat exchanger and is only a couple of feet from the exhaust port you see on the side of your rig. High efficency type furnaces cost a whole lot more.

[ols1932]

Ditto what jimcol says. The furnaces in RVs are notoriously inefficient. That's why most use some type of additional heater such as 1500 watt electric heaters, Wave propane heaters or other type of heater that is more efficient.

Orv

[Marc Morgan]

Thanks guys for your response. I understand about the efficiancy but how is this any different than my gas log fireplace in my house which is ventless. All the heat comes out into the room( house). Is it because the 5th wheel is a smaller compartment and the build up of CO is much greater? So the exhaust port carrying out CO is also carrying out lots of heat with it? And what you are saying about more expensive higher efficiant furnaces is they can divert more of that exhaust heat back into the camper without increasing the risk of CO poisoning?
Its just that the heat from the exhaust vent is much greater than any of the heat coming from any of my vents inside the camper.

Thanks again
Marc

[jimcol]

Marc, I am certainly not a gas heating expert. There are a few on this site, like Ozz, who may come along later with a more technical explanation for you. Your vent less gas log fireplace in your home is a sealed unit. Ultra efficient but expensive. These type systems have a way of extracting more heat from the flame passing less heat out the vent with the carbon monoxide. The reason your exhaust is much hotter than the air out of your duct work is relative to the distance it travels, the size of your heat duct compare to your exhaust duct, and the temperature of all ducts before the heating begins. It gets pretty cold in the belly of your 5ver before the furnace kicks on. That entire cold duct has to be heated up before you feel warm inside.

[Ozz]

Everyone really explained it pretty well, our trailer furnaces are just not energy efficient, my home furnace has a plastic vent pipe, so that tells you that it is very efficient, they vary greatly in home units, even up to over 90%. Your heat exchanger in the trailer raises the incoming room temperature around 30 degrees (average). A cold trailer will have 'just warm' furnace supply air, a warmer trailer will have almost hot supply air, but it will never be the same as the hot combustion air coming out of the vent outside.

[2 for Him]

Does anyone sell a higher efficiency unit? With all the "green" concerns and cost of propane someone should. If not, looks like a business startup to me.

[Bob & Lee]

I had thought about what would hapen if I poped the vent back into the underbelly and at least use it to heat the pipes ..but the fxaust gas ?? I looked around and this article was interesting

http://www.solarhaven.org/HPArticle.htm

Bob

[Ozz]

One could just get a heat pump, but I personally don't like them, the compressor runs almost 12 month's out of the year, many more components to fail, and the heat often has to be backed up and supplemented by an electric strip heater.
Bob, it was thought provoking, but gave me a headache about half way into it.
Tom, for the cost and space needed for it, I don't think it would be a good investment. (But that's probably why I am still working, fixing things..)

[sreigle]

Since the heat is from burning propane, would the gases in the exhaust be the reason it is exhausted outside? Safety, in other words? It sure seems like some of that heat could be used to heat a closed system before being pumped outside, though.