Recycling Furnace Exhaust Heat?

[Rocketgirl]

I am spending my winter in North East PA in my Sunline 1950. As reflected by my other posts, I have decided to pack straw bales under the perimeter of the RV, in black contractor bags to minimize additional moisture from rain, and then finished it off with a cheap white skirt made of thin styrofoam, for looks more than anything.

As I was checking that the exhaust output from the PROPANE furnace was not heating any straw or styrofoam, I realized there is a lot of heat being exhausted and wasted into the air.

My question is, what would be preventing me from running a wide dryer duct hose, from the external furnace output to heat the underside of the RV? Especially near the holding tanks in the rear?

The underside is pretty well sealed with straw bales; could the carbon monoxide rise up into the RV?

Is there any way to mitigate carbon monoxide while it is in the tube, before it goes under the RV? Filters? Scrubbers? Binders?

Also, could I cause damage to the furnace by channeling the exhaust rather than letting it spew in all directions outside of the RV?

Yes, I do have smoke, propane and carbon monoxide detectors in the RV.

I enjoy this level of sustainable creativity... Your input/feedback is welcome.

Andrea

[Janalee]

Andrea..you are contemplating creating a dangerous condition...in many ways! I am sure one of our more knowledgeable engineers will chime in and, hopefully, change your mind. Please keep in mind that your Sunny was not built to be a full-time winter home.

[Rocketgirl]

Thanks for your response, I was thinking it would not be worth the risk once I read that even inside the trailer there is a risk in general with normal operations just from a bad mixture. I will probably just take one of my interior outlets and redirect it underneath.

It would be cool if something did exist to recycle all that heat being wasted/blasted out into the air.

[JohnB]

Hi Andrea,

I know you are just thinking and asking if this is a good idea or not, in this case this one is better not done. Good for you for asking first! As we have said before, ask any questions and we will try and help as best we can.

There are several concerns with what you are thinking about. The first is the saftey aspect and here are 2 of on the top of the list.

The furnace has to vent outside to get rid of the combustion gases and the excess heat that is not removed by the inside heat exchanger. If either of those are disrupted, it will be a problem. The exhaust gases cause carbon monoxide concerns if not directed away from the camper and the excess heat that cannot escape fast enough by a partially restricted exhaust vent, will over heat the furnace inside and keep shutting down the gas valve for high temperature.

The standard RV furnace is a true convenience. You can run the camper off the grid by only using LP gas and a 12 volt battery. It works well for short trips to warm up the camper on a cold morning or any other time. It however is not really efficient. They use (waste) a lot of propane while burning and they waste heat energy in the process. You have found the wasted heat as the system cannot remove enough heat from the burning gas before it blows outside. On a home gas furnace, they burn cleaner and are truly more efficient from a gas usage perspective and the heat exchanger system inside the furnace is orders of magnitude better. And naturally, the furnace costs orders of magnitude more too...

If you need more explaining, let us know, glad to explain more so you know.

Hope this helps

John

[Rocketgirl]

Awesome, John, thank you for explaining more about the RV furnace and how it functions. You answered all my questions and confirmed my suspicions, about constricted exhaust, safety, etc. I guess the heat will have to go into the air.

RV's have such potential for sustainable, affordable living. I'll have to keep my eyes open for more efficient furnace options. I am warm and cozy, it was simply a creative thought on how to recycle heat. I used to re-direct my electric dryer outlet, filtered, into the crawl space of my house to heat the crawl space. But that did not contain carbon monoxide.

[mainah]

There is also another problem the exhaust system is a coaxial pipe that brings in combustion air and outputs propane exhaust. The ideal is for O2 depletion inside of the camper that other wise would have been used for combustion. Propane also produces a great deal of water vapor.

[Jim-Bev-2363]

Whatever is used for insulation, straw/fiberglass/foam panel, I would think some venting would be needed like foundations to site-built homes. Fresh air is used to control moisture buildup, I think.