rv furnace outside exhaust

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millie001

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Nov 27, 2018
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I read somewhere that you should not feel hot air coming from outside exhaust vent as this means you are losing heat from inside is this true if so how do you fix it?
 
I'm not sure where you read that......Mine has a "Caution HOT" label. As it is exhaust from the burner it should be hot.
 
Welcome to the forum.
That is not true.  You will feel heat coming out of the exhaust tube. It's from the propane burning.
 
You should feel heat only when the furnace is running except for about 30-45 seconds when the furnace is first turned on.
 
An RV's furnace draws OUTSIDE air into the combustion chamber to allow the fire to burn, and exhausts the hot gasses back outside.  Inside air circulates around the combustion chamber to be heated and returned to the interior.  So warm inside air is never exhausted outside by the furnace.
 
All the above is true. And that really gets my dander up, as though the manufacturers say the furnaces are 70%+ efficient, from what I've read, some are closer to 50%. The furnace manufacturers and RV manufacturers are still using 60 to 70 year old technology. Other than initial cost, for the life of me, I don't understand why they don't make a lot more efficient furnace. This is the 21st century after all. And the technology is already out there. It's not like they have to reinvent the wheel, they just have to apply the technology that's out there.
 
In fact the exhaust will be hotter than the air inside the RV.

Making them more efficient means making the heat exchanger larger. and in an RV space is at a premium.  So I would gather that is the reason for the lower efficiency ratings.
 
John From Detroit said:
Making them more efficient means making the heat exchanger larger. and in an RV space is at a premium.  So I would gather that is the reason for the lower efficiency ratings.

It's true, but who wouldn't give up another 3-4 cubic feet to use half or less the propane? The 90% efficient home units use PVC pipe as the exhaust and the exhaust air is just warm.

On the other hand, hardly anyone thinks about furnace efficiency when their eyes are all aglow as they contemplate the purchase of a shiny, new rig. By using ancient technology they can keep the price down, but it would be nice if it was at least an option. Once better furnaces started appearing I think they would eventually become the norm as consumers became aware of them.
 
Heating an RV is almost laughable.  Yes, they can be heated but the amount of electricity or propane expended to keep them comfortable in colder climates can be eye opening.  But to your question as 100 percent of the replies have stated - YES the exhaust will be hot just as it is on your car.  Gotta have some way to get rid of the carbon monoxide generated by an open flame.

Bill
 
Back2PA said:
It's true, but who wouldn't give up another 3-4 cubic feet to use half or less the propane? The 90% efficient home units use PVC pipe as the exhaust and the exhaust air is just warm.

They would also need to blow a lot more air over the heat exchanger in order to make it useful. That would use a lot more electricity. As it is, the furnace can run down a pair of batteries overnight.

Joel
 
LOL. Referring to the RV furnace internal design as a "heat exchanger" is a joke. It's just a tin can with a flame inside, not even any fins to help. Efficiency is lucky to be 55%, and the ducting systems supplied in the RV are equally shoddy.  It is entirely possible to design a much more efficient furnace without a huge increase in size, but neither the RV appliance makers nor the RV builders want to invest money is a new design, so the furnaces have been unimproved for the last 30+ years.  You don't need a larger, high power fan either, so there is no increase in 12v power. Perhaps even a decrease, since a more efficient furnace should end up running less hours/night.


Ditto for RV air conditioners
 
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