Adding filter material to heater intake panel

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djw2112

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Has anyone ever added filter material to their heater intake panel?

Im not talking about those thick 1/4 to 1/2 inch cardboard border filters for home heater units.  I am talking about the same flat perferated foam material that is typically in RV AC units on the inside panel. 

Years back i built my own Bad A$$ PC with top of the line everything and i wanted to keep it dust free inside the case. So alonq with using positive pressure on the inside of the case with fans I also contacted this guy via his UNI ebay store at the time.. 

http://shop.unifilter.com/c/accessories_foam-sheets

  We talked about what i wanted to do and he suggested a flat sheet of that foam filter and the air flow percent (comes in dif percents) that he thought would be best for my use.  I got the sheet and cut it to fit both in my lower and front fan intakes of my PC and it works great, collects all that stuff you dont see in the air and i clean it 1x month.

So i was considering replacing the sheet of the same material in my RV AC unit and also thought i might use it in my heater intake.  It would have to be really secured good with velcro or screws to the intake panel for the heater because if it comes loose it could catch on fire if it comes in contact with the heater. 

Some people (as i was also) are concerned about this stuff getting brittle and little hairs of it comming off, but at the time i ordered he said theirs lasts 7 years without flaking.  I use the red stuff in my PC and so far it has not flaked at all.  Its not cheap, if i remember it cost me $19 for a sheet of it about the size of my PC keyboard but its worth it if it helps prolong the life of something.

Thoughts ?
 

Back2PA

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My first concern would be that the unit wasn't designed for it and a filter, even if only a little, would impede airflow
 

kdbgoat

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^yep^ The couple of manuals I have looked at, the manufacturer says don't put anything including a filter in front of the return. It can impede the airflow as stated above. If airflow is impeded too much, the sail switch will not allow to furnace to light. Even if you don't have that happening, it's still possible, though not probable, to overheat the furnace. The normal stuff floating around the air won't hurt an RV furnace.
 

Gary RV_Wizard

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Give it a try. Either there is enough air flow or the furnace will occasionally shut off because its high limit temperature is exceeded. Not a big deal as long as you remember that the extra filter is probably the cause.
 

Old_Crow

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I've had the return grilles off both of my furnaces and the way they are mounted in the coach you probably don't even need the returns. 
For example my front furnace return is under the fridge.  The area behind the grille is also open to all the kitchen cabinets, the back of the washer/dryer compartment and the outside of the coach(through the compartment where the furnace itself is housed).  I don't think putting a filter in front of that return grille would accomplish a thing.
 

Rene T

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In my fifth wheel I have three steps leading up to the bedroom. 2 of the risers have grills which are the cold air returns. They just go into the front compartment where the heater is located. I wish there was some way of running duct work from these grills to the heater.  When it's cold and the fireplace electric heater will be enough, we lay a towel over the steps to stop the cold air from the compartment from entering the living space.
 

Gizmo100

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I wouldn't add the filter..The heater would most likely have to work harder to overcome the restricted airflow. And would most likely burn more gas in the process.

It was designed to run without a filter..I would leave it alone.

Rene T said:
In my fifth wheel I have three steps leading up to the bedroom. 2 of the risers have grills which are the cold air returns. They just go into the front compartment where the heater is located. I wish there was some way of running duct work from these grills to the heater.  When it's cold and the fireplace electric heater will be enough, we lay a towel over the steps to stop the cold air from the compartment from entering the living space.

While I get the purpose of the towel...I would be nervous about anything on the steps that you could trip on. 
 

Back2PA

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Gizmo100 said:
While I get the purpose of the towel...I would be nervous about anything on the steps that you could trip on.

Rene and I have the same fifth wheel, and coincidentally I too have a mat in the same place, but primarily because that's a narrow high traffic area that will show wear and collect dirt (I live in mine full time). The mat is thin enough that it stays in place without being a trip issue. I haven't really noticed the cold coming in, probably because I have a freezer in the storage compartment that contributes a little heat.
 

Gizmo100

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Back2PA said:
Rene and I have the same fifth wheel, and coincidentally I too have a mat in the same place, but primarily because that's a narrow high traffic area that will show wear and collect dirt (I live in mine full time). The mat is thin enough that it stays in place without being a trip issue. I haven't really noticed the cold coming in, probably because I have a freezer in the storage compartment that contributes a little heat.

THAT'S IT.....Rene you need to get a freezer.
 

Rene T

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Gizmo100 said:
While I get the purpose of the towel...I would be nervous about anything on the steps that you could trip on.

Thanks for your concerns Gix, but that hasn't been a issue. We keep the towel fairly tight and no one has ever tripped.
Watch what happens now. :-\ :'( :)(
 

Gary RV_Wizard

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It was designed to run without a filter..
The Atwood install manual is largely silent on that aspect. It specifies a minimum intake area (80 sq in) and cautions against blocking the air intake with objects, but leaves the ducting in & out to the installer.  I've seen furnaces mounted in the basement with air intake from up top and those typically have a coarse mesh screen or filter, most likely because objects and dust bunnies on the floor could get sucked right in. 


It's true the furnace itself doesn't require filtering - the fan pushes any dust right through the burner chamber. The reason for filtering would be to reduce the dust collecting in the outlet ducts or simply getting blown around the cabin.
 
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