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Lali 10-27-2009 04:59 AM

Furnace Questions
 
I am a new user, not a pro, so didn't go into HVAC. There is an Armstrong Air Tech furnace in the unit in which I reside. Has anyone out there ever heard of there being no place in the furnace to put a filter??? My landlord has made a place for me to put one in the cold air return, which is only using one third of the filter. I am having difficulty breathing without having a window open. Also saw during my browsing that there is a problem with car exhaust entering the furnace. My home is surrounded on three sides with constant traffic. Could someone please advise. Thanx.

Just Bill 10-27-2009 05:30 AM

No, I never heard of a forced air furnace without a filter. Besides filtering the air it circulates, it helps to keep the blower and components clean. It is usually located in the cold air return, just before it enters the heater.

Heaters are often installed with outside air for combustion, but the air that circulates in the living space is seperate from the combustion air, or should be. If you have windows open, whatever is outside will also be inside. It is impossible not to have some air leakage in a house, but keeping doors/windows closed will keep out auto exhaust fumes.

CustomBuild 10-27-2009 08:08 AM

Try looking at the cold air grille in the wall/ceiling/floor. Sometimes there are wing nuts or screws with slots big enough for a nickel. If there are, open the grille, and the filter may be in there(or a place to put a filter). If there isn't, you can purchase this type of grille at the hardware store.

Lali 10-29-2009 05:34 AM

Thanx for your replies. In my original post I stated that my landlord has made provision for a filter in the cold air return (which is inside the grill, below the ceiling, entering the furnace from above). Is this as effective as a filter that fits inside the furnace itself? This is a one level, cement floor home (no basement). Shouldn't the grill be closer to the floor, where the cold air is??? Also, the outside cold air intake is approx. 7 feet from the main road into this complex. How can one avoid the exhaust fumes? Prior to my tenancy, there was no filter anywhere. How could any of the reno dust, etc. be filtered & will what is in place now eventually filter all the crud? Thanx.

Lali 10-30-2009 05:09 AM

Hi! I'm new at this. Left a thanx & couple of more questions on my thread 'Furnace Question'. Read a couple of your other posts & you should write a book buddy! Very detailed info. And I agree, it's great to share knowledge & it is far more difficult to describe 'how' to do it than it is to do it. Aloha!

CustomBuild 10-30-2009 05:24 AM

Quote:

Originally Posted by Lali (Post 346816)
Thanx for your replies. In my original post I stated that my landlord has made provision for a filter in the cold air return (which is inside the grill, below the ceiling, entering the furnace from above). Is this as effective as a filter that fits inside the furnace itself? This is a one level, cement floor home (no basement). Shouldn't the grill be closer to the floor, where the cold air is??? Also, the outside cold air intake is approx. 7 feet from the main road into this complex. How can one avoid the exhaust fumes? Prior to my tenancy, there was no filter anywhere. How could any of the reno dust, etc. be filtered & will what is in place now eventually filter all the crud? Thanx.

A filter placed where air enters the cold air duct theoretically is as effective as one placed near the furnace, providing the duct is airtight. The cold air return is placed in a spot that it will be most effective according to the climate of your area. If it will be most typically used for air conditioning, then the intake placed in the ceiling is most effective, because the air entering it is the warm air that needs to be cooled again. However, if this is not the case, the installation was probably done with cost being a major factor, and they didn't want to foot the bill to have the duct extended to the floor, where it should be. To retrofit it now would be an enormous cost and likely an enormous inconvenience, due to the extensive amount of work that would have to be done.
The outside air intake is only used for combustion, so it never enters your house. The exhaust being drawn in is not a concern because it exits your home with the combustion exhaust from the furnace. The only reason that the furnace brings air from outside to burn is that without it, as combustion exhaust exits, it would draw air in from your windows and doors to displace the air leaving, creating drafts and introducing outside contaminants to the inside of your home.
What dust/crud was in your home before the filter was in place has likely settled onto the surfaces of your home. Regular dusting is what will remove it. But I think your concern probably lies moreso in what is in the furnace. It is without a doubt that it is in need of a cleaning, and I would ask the landlord if he has a service contract in place. Most contracts provide for a yearly cleaning.
It is nearly impossible to create a perfect, allergen free environment without commercial clean-room equipment. All you can do is use high grade filters, and if you can, buy a quality stand alone air filter/ionizer. If your concerns are stemming from an allergy problem, maybe your landlord would be willing to split the bill with you to have a U/V filter installed in your cold air return.

Lali 11-03-2009 04:51 AM

Thanx, this alleviates some of my concerns. Last year I purchased a metal framed electrostatic filter, have a free standing ionizer and have placed double filters in the vents & still everything is covered with either white dust or dirt within a day following dusting. Know that the furnace & vents have probably never been cleaned in these units within a period of over 35 years & that the landlord refuses to clean them (this is subsidized housing located almost in igloo country). Any further suggestions other than dusting or having them cleaned myself?

beenthere 11-03-2009 06:01 AM

Putting in 2 air filters is not a good idea. Usually, the duct system is undersized to begin with.
So adding a second air filter, just makes it harder for the blower to move the air. And can cause the furnace to over heat, and shut down on high temp safety.

Lali 11-03-2009 06:20 AM

Thanx. Guess I should have said double filters were placed in the ducts. Will this have any bearing on the efficiency of the furnace?

beenthere 11-03-2009 06:37 AM

Yes. It slows the air movement. Which means it has to run longer to do the same job. Plus tends to overheat the heat exchanger, which can lead to early failure. And Co could be introduced into your home. From the failure

Lali 11-03-2009 06:51 AM

Thanx.OK. I'll change them to single filters. Even if the duct covers have gaposis (do not fit snugly)?:)

beenthere 11-03-2009 10:52 AM

Before you remove/change them.

Check the air temp from teh supply register closest to the furnace. And then after you change them check it again. You should notice a difference.

hvac122 11-03-2009 11:31 AM

Most dust in the house is from infiltration. This means it is comming from the outside through holes in the structure and getting in the house that way. The furnace is only going to filter the air that enters the return air so not all of the air is cleaned.

Sounds like you have infiltration problems. the only way to tell for sure is to have a blower door test done which will tell you how much air is leaking into the house. How well is the house sealed up? Do you feel drafts or leaks?

Lali 11-04-2009 05:02 AM

Thanx for your replies. Too late, already changed filters to single. I'd say infiltration is highly a likely problem. These walls are like paper (I can hear my neighbors every word & movement, not to mention being able to hear & feel the vibrations of every vehicle that passes by). You can see daylight under & around front & back doors. This particular unit is ground level, has a cement floor with the lino placed directly on top without any wood between. Know this off furnace topic, but isn't there a building regulation about this? (in Canada) When the furnace shuts off the floor becomes freezing. The antiquated insulation in the attic, I am told, is shredded newspapers & is over 35 years old. Whatever is in the walls is questionable as well. Does anyone know the specs on insulation? God Bless y'all! :detective:

CustomBuild 11-09-2009 04:52 AM

This link will give you more info than you will care to know. It says that your attic insulation is probably rock wool, which it describes as grey to white, and with black specks. I could see where that would be mistaken for shredded newspaper. As far as the floor goes, linoleum glued to concrete is typical. In newer homes, there is a thermal break between the foundation, and the floor slab, so you don't get that colld floor. Not much you can do, other than throw rugs.http://www.ornl.gov/sci/roofs+walls/...on/ins_16.html


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