I purchased a house in 2007 that had been fully renovated in 2005. Part of the renovation included a new high efficiency Heater with central air. I recently discovered that the 2nd floor cold air return lines (insullated flexible ducts routed through the attic) all converge in a 3ftx3ftx8ft tall cavity on the 2nd floor directly above the air handler... the floor of this cavity is devided in half... one 1/2 is directed into the cold air return of the furnace, the other 1/2 is directed into a channel that vents to (2) 4inch vents throught the exterior of the house. I have seen a few forums on-line discussing the benefit of this type of 'open' exterior venting into the air return, but I would like to know if it is really necessary and if it should be regulated somehow (insulation, dampers, etc...)????
Type of HVAC: Air Conditioner
The section with the two vents that go outside. Do they vent into Furnace closet. Russ
Do not understand bad service rating. Needed more info. Some installs have parts of the combustion air from furnace vented that way from outside. Just trying to find out if that was the case. Russ
45 years of experience install design and repair of all makes and models of AC
Sorry about the confusion with the rating, work firewall blocked your response. Now, to answer your question, neither of the 4" vents go to the furnace room.
OK. understand . This is for ventilation under floor. These vents are used to have some air circulation and to prevent any mold or mildew from forming on return.
Won't this increase the load on the AC coil? ... Other than this one cavity, all other duct work is insulated sheet metal or tubing. I don't understand concern about mildew or mold forming on the return.
If the return air gets to cold and air temp around it is warmer it could reach dew point sweat and cause mold. My concern is that it is not insulated. You are correct it will increase the heat load on air handler. If possible I would insulate the return. Also check for any cracks and seal them with caulk. Just sheet foam insulation you can buy at Lowes are Home Depotwill work fine. Russ
Any insulating you can do on return will help. It is code now that all return air ducts have to R-6 insulation as the supply. Russ