I have forced hot water heat, but installed a central air conditioner (Lennox) and a Pureair air purification system (they installed ductwork for the air system). Obviously, I only run the air conditioner in the summer, but do keep the air purification system running all of the time.

If I had forced air for heat and cooling, I am assuming the return air on the purification system would be warmer in the winter, but since I do not, the return air is quite chilly. I've always just turned up the heat to deal with it, but guests are always telling me it's so cold with the air returning.

I don't want to turn off the purification system in the winter, but is there a way I can keep the air from being so cold? Can I cover some of the return vents? I wouldn't cover all of them. I have a total of 8 returns on one floor. Can I cover any of them? Thoughts? Suggestions?

Thanks!
Lydia

The return is called the Cold Air return. Cold air is heavier the warm and settles to floor and to you fan unit to get warmed up. I don’t think your air cleaner has anything to do with your problem.

It is had at this distance to put a finger on the problem. You should not close of these returns as this will starve the unit for air to circulate.

I suggest you call the company that installed the system and have them check it out. Something may have come disconnected allowing cold air to get in to the system.

Thanks WOW. I don't think anything has disconnected, it's been this way since it was installed. The air purifier and air conditioning goes through the same duct work. The heat is completely separate. The air is circulated through the system and filtered, then returned back to the cold air return. I don't think there's anything for it to go through to get warmed because it's separate from the heating unit.

The air is taken out and goes to the system in the basement (not heated) before it comes back to the cold air return, which is why I think the air comes back colder than what it was when it was taken out.

There are three large rooms that have 2 cold air returns in each - do you think that one of them could be closed in each room or would that starve the unit for air to circulate as well?

Heat has to be going somewhere - or if you prefer, the cold has to be coming from somewhere. Let me throw out a few ideas:

If the air is spending any time in the basement it will radiate heat into the basement. Since the basement is not heated radiated heat would be near the system, not through out the whole basement or room in the basement. No air leak needed, just the duct pipes being surrounded by cold air will transfer heat from the warmed air inside to the cold air outside.

Warm air rises, so the heat would radiated out of the system and climb, pulling more cold basement air to the pipes/ducts and cooling your heated air. Its a continuing process. If the immediate space (say 6 inches to 12 inches) over the duct work is noticeably warmer, then you can be certain that that is where your heat is going.

In essence your system may be trying to cool the basement not through forcing warm air through the ducts, but by radiated warmth from the air inside the ducts to the colder space - especially true if the return ducts are not insulated.

Easy to tell in the basement, plain sheet metal is uninsulated, foil (like tin foil) wrapping means insulated. If the ducts are not insulated your losing heat to the basement. You need to have those ducts wrapped to hold the warmth.

There are different kinds of duct work. The round 'tube' type comes in pre-insulated or pre-wrapped form and non insulated/wrapped. The box or rectangular ones usually do not come pre-wrapped and need to have a wrap put on on site.

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Different areas have different Building codes. In counties here in the Central Valley of California some allow uninsulated ductwork in places like cellars and basements and between walls, insisting on insulation in roofs, crawlspaces or places that are vented directly to the outside. Other ares minimum code insists that all duct work is insulated.

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It is also possible that your ductwork is running along side or near an exterior wall, picking up cold (leaving behind heat actually) there as well.

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IF the air is not moving swiftly enough through the ductwork - say if there are already too many vents closed return or otherwise - then the air is sitting under the floor, or in the wall, or in the ceiling (where ever the pipes run) and is radiating most of its heat before it returns.

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Since you have a purifier system does it ventilate or suck in 'fresh air' or have that option? Some systems can ventilate the house, basically they pull in fresh air and push out house air - this kind of system is used either at night where the nights are cooler and one can more efficiently cool by pulling in the night air) or in other areas with real seasons where there are several months a year where the temperature outside is fine to great you may not need to heat or cool on that day, but circulating fresh air into the house will cool the house and give you fresh air.

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It is also possible that the air purifying system pulls in air from the basement directly at the system - so its pulling in 'fresh' cold air from the cellar, mixing it in with the warm air, it may be as simple as closing a vent at the machinery of the system.

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Another issue is that its possible that duct pipe has slipped or come loose, pulling in cool air from the basement or attic.

Unfortunately too many installers do not use screws, they only slide the duct-work into each other then use foil tape to hold it together. Foil tape is not designed to hold duct-work together, it is designed to seal up all cracks and holes (screw holes) to make the duct work as air tight as possible. What ends up happening is that soon after installation even during installation of the ducts the pulling and general expansion and contraction due to heat and cold causes the individual segments to work loose even to the point of falling apart.

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The system should have been designed to accept an optimal number of vents and returns - meaning that the number of returns open are the number installed in each room to the number of vents that let the conditioned air in. If you close a vent in a room that 'sucks' air to the filter, then you will need to close the vent that blows air into the room.

Well, I went to the basement to take a look at the duct work to see if it was insulated or not. It appears that everything coming from the unit for the air conditioning is insulated with a gray padded material. The ductwork that is coming from the air cleaner is just metal with no covering at all. I have no idea what that means.

I do not believe it sucks in fresh air at all, I think it filters the air that is sucked from the house and puts it back through the incoming air vent. It's the type of air cleaner that removes allergens, spores, particles, etc.

So what we are looking at is air conditioned air is insulated (going to the rooms) and the return duct work is not insulated (coming back)?

If so then the equipment might have been set up for both hot and cold forced air, the idea being that it wasn't necessary to insulate the return air since it would be reheated/recooled before being sent back into the house. But you are not heating at the A/C unit, you are heating through plumbing/pipes and the air is not being reheated.

If it is just a short duct from the air cleaner to the other unit and then return ducts are insulated I doubt that much thermal loss could be present. However you could 'experiment by throwing on a blanket or two over/around that duct to see if any improvement in air temperature takes place.

I took a gander at the Lennox site and this: http://www.lennox.com/pdfs/manuals/Lennox%20PureAir%20Manual.pdf to get a better idea of what we are looking at. I assume that if the filters are not seated properly at the purifier unit that the unit will not come on. If it still runs even without the inserted HEPA and mesh filter, pull each and see if you can push them back into their slot to 'reseat' them. There is most likely a gasket around each filter. Further if you have a sliding door/drawer to your unit make sure it is completely closed. Again I assume that there is a gasket - it is not shown in the little video of the unit that I found here: http://www.lennox.com/products/overview.asp?model=pco I doubt that a leaky seal at the unit itself would result in too much air cooling or sucking in cold air from the basement.

Since in your first post you said 'I have a total of 8 returns on one floor. I guess you have two or more stories.

What you could try is shutting off the return(s) on the first floor, and opening up the returns all the way on the top floor. Open all the doors inside the house to allow the heated air to rise to the top floor. What should happen is that the hottest air should be sucked into the ducts, circulated and pushed out at the ground floor.

That should result in warmer air coming into the downstairs returns. If not then you are still getting substantially more cold air from someplace else - a busted pipe, a A/c venting hole - something.

Mind this is a 'temporary' fix that is not a permanent solution - but can tell you a few things about what is going on while hopefully increasing comfort levels until you get an HVAC specialist in there to look at what you have.

The reality is that your system is highly inefficient, and is going to run you a lot of extra money in heating (and potentially cooling) energy. I wonder if on hot summer days if your A/C isn't having to work overtime to compensate as well.

There is a science to the sizing and placement of ductwork - factors like air friction, static pressure blah all have an effect on the end result of the air. if this system was installed with too large or too small of duct work then the result would be inefficiency in heating and cooling.

David - - thank you again!! There are 8 returns, but it's all on one floor (1800 sq ft). It's pretty spread out and very open, which is why they probably put so many returns.
There is a pretty significant amount of duct work from the air purifier (don't know if this is coming IN or going OUT) that is not insulated so I would imagine it gives the air a good amount of time to get cold in the winter.

Thank you SO much again for all of your insight!

Your welcome, sorry I can't be of any more assistance.