Stopping draft from furnace return

[trustymopars]

When we camp, we normally use the fireplace and a ceramic heater for heat. On our first trip in cold weather a few years ago, we noticed a cold draft coming from the furnace return vents under the stairs. I had some cardboard on hand, so I took the covers off, and put some cardboard behind them. We haven't camped in any really cold weather since, until Halloween weekend. The temps one night got into the 20's, so I woke up at 2:00 and, worried about the pipes freezing, got out the screwdriver, so I could remove the cardboard and fire off the furnace. I have found a better solution - 4 10x6 louvers and some 1/2" aluminum angle. I did have to modify the step supports, but everyting went back looking factory! This would seem so easy to do from the factory.[/img][/img][/img][/img] Not really good at posting photos, but mabe you can get the gist of it. JT.

[DarMar]

Excellent mod, as we have pondered this situation this fall and decided a solution was to be found with our winter to do list. In the cool spring and fall weather it is really amazing how much cold air draft can be found coming from those vents. Thanks for posting, where did you find those louvers?

[DQDick]

Great idea, but be aware that Atwood says not to mess with the return air or vents in anyway. We had some discourse with them at the Rally over putting filters there and also running the furnace with the slides in. They were against both ideas.

[Irlpguy]

quote:Originally posted by DQDick

Great idea, but be aware that Atwood says not to mess with the return air or vents in anyway. We had some discourse with them at the Rally over putting filters there and also running the furnace with the slides in. They were against both ideas.

Did they offer any explanation Dick as to why they were against both ideas, or just left it at that with no explanation offered.

Just curious....

[bigskyjimmy]

I was wondering why you can not do that either since there is plenty of air that can be sucked in from the basement,my basement panels do not even go to the top in the basement ,I have put filters under the stairs and that helps in the winter with no ill affects but I would rather just block them off

[trustymopars]

quote:Originally posted by DarMar

Excellent mod, as we have pondered this situation this fall and decided a solution was to be found with our winter to do list. In the cool spring and fall weather it is really amazing how much cold air draft can be found coming from those vents. Thanks for posting, where did you find those louvers?

We have a local store called Southeastern Salvage that deals in closeouts and seconds in home improvement products. We were looking at hardwood flooring, but came home with these. As far as air flow, I don't see how there would be any reduction, since it only blocked off three of the slots on each return.

[dsprik]

We were told by Keystone also about the return vents a few years ago. Apparently, the return - on my 2007 3400 anyway - is marginally large enough for return air coming out of the factory. Seems the engineers did not want to over-engineer those ducts. Not sure why... I know later year models went to two return air ducts in the stairwell. Then they threw the converter down in there, which I can't believe was helpful to the air flow.

[DQDick]

It was air flow issues and their feeling that the manufacturers don't put any extra vents or extra return air in their plans. If you are noticing incomplete ignition (smoke residue near the furnace exhaust) then you for sure have an issue.

[Ozz]

Sweet mod! It will restrict the return air some, you could take the temp of the supply air under a controlled condition, (interior temp about the same for test) Test with the cover on with louvers, and then without, if the supply air rises 10 degrees or more, it is a restriction you would not want. They don't want the furnace plenum, or discharge too hot, it would cycle the furnace on the high limit.. and if the high limit would fail, and they do.. bad ju-ju..

[oldelmer1]

We never usr our furnace, so I blocked off under the steps and under the refrigerator. What a huge difference in heating and cooling.

Also have 2 75 watt drop lights in the basement to keep it warm down there too.

[Irlpguy]

trustymopars, that looks like a great solution to keeping most of the cold air from entering and yet allowing air to be drawn into the basement area by the furnace if required.

Unlike a home system the cold air return in our RV is not a closed system that can be completely filtered or one that is limited to a specific area. Our RV furnace draws air from the whole basement and storage area, as well as the living area through these vents. It would be great if this system worked the way our home does, then we would not have the cold air coming in from the storage area, we would be directly connected to the furnace, reheating air previously heated from within the living area, also we would be able to properly filter it.

As far as the furnace burner is concerned, the air supplied to it comes into the furnace from the "outside" around the exhaust pipe and is supplied by the same motor but different fan located in the sealed compartment open only to outside air. The only way to restrict that would be to block off the screen on the outside cover.

IMHO you will be just fine with the mod and I will keep my eye open for something similar.

[Ozz]

The plenum would be overheated if you blocked the inside air return.

[trustymopars]

Ours does have the inlets on both steps, so maybe no more than we use it, (twice in three years), it will be OK. JT

[fauch]

The reason for a non closed air circulation system in these styrofoam boxes that we sometimes call home is CO POISONING POTENTIAL. Some outside air makeup is good. Everything that burns propane or other hydrocarbons produces CO.... stove, furnace, generator, refrigerator. A generator is even a bigger challenge, since part of using one safely is to close potential entry points for exhaust fumes, while not closing off all fresh air makeup.

RV Safety advocates say every year 500 people die inside of RV's from carbon monoxide poisoning. They say the best defense against that happening is a CO detector. New RV's will already come with them, but if you've got an older model then you need to check your RV.

[Irlpguy]

Atwood has done a decent job of isolating the exhaust from their furnaces from getting into the return/cold air supply. The outside cover on the furnace is gasketed, the burner fan compartment is sealed from the rest of the furnace and when you stand outside the exhaust blows away from the RV quite well and is not located near any intake for the furnace.
The Fridge also is well isolated from the inside of the RV with caulking and is well ventilated with the louvered covers.
Anyone using the stove should use the fan above it and have a window open as well to help exhaust those fumes.

Other than catalytic heaters the generator has the greatest potential to have fumes enter the living quarters.

When we run our furnaces air can and will be drawn in from any source to the outside, that includes the length of the underbelly and any other opening from the storage area shared with the furnace. If we blocked off the supply from the living area at the steps would we sufficiently reduce the air required to cool the furnace chamber and therefore cause problems with the furnace? I think that is quite possible, "unless" you leave a storage door open somewhat or provide an adequate sized opening in some other area of the basement.

My previous point of having all the air to the circulating fan come from cold air returns within the RV would be ideal. We would then create a vacuum within the living quarters and by leaving a window open at the rear of the RV farthest from any potential fumes we would reduce the possibility of drawing them into the furnace.

I completely understand why this is not done but it would be great.

[richfaa]

It is good then that we do not use our furnace all that much as we manage to stay in moderate climates year round. the fireplace takes the chill off any chilly mornings. We use the A/C far more than the furnace.

I will say one thing about this 2013 3402 big Sky. It is far tighter than our 2006 3400 and less drafty particularly around the slides.