I've searched through the boards and now know that I need at least 1 cold air return for each floor of my house. I currently have 4 returns on the first floor. 1 kitchen, 1 living room, and 1 in each bedroom. Its a small house, under 1500 sq ft. Given that background, here's the question.
I'd like to remove the cold air return in the kitchen since its location is the only place available to put in a dishwasher. I'd like some advice before I call the local HVAC people and pay them to tell me "nope, not a good idea. Here's your invoice for the consult."
You should not have a return duct in the kitchen. I do not see any issue with closing this up as it most likely will not change any air flow to the rest of the house. Ideally returns should be in all rooms but kitchen, baths and within the utility areas and laundry rooms of a home. I will send you a bill for this consult.
Posts: 1012 | Location: New Jersey | Registered: 31 January 2006
Depending on the size of the return air inlet in the kichen compared to the sizes of the other ones, removing it could cause the air velocity at the other returns to increase to the point where they will be noisy. There will be perhaps one-third more air being drawn into the other return grilles than there is now. Also, your return ductwork may exhibit the same problem, or your air handling unit could be starved for return air. Your system was presumably balanced when it was installed, and for best performance, that balance should be maintained or restored after any changes. Can you relocate the grille, perhaps to the other side of the same wall?
No charge.
Architect (NY) and Home Designer (PA)
Posts: 2487 | Location: Tobyhanna, PA | Registered: 24 October 2005
This all came about for a couple of reasons: 1. We'd like to put in a dish washer. The only place one will fit in the kitchen is right on top of that return. 2. (More importantly) The duct work in the basement is a mess and we'd like to get the basement finished off.
Coming out of the furnace is a 8" diameter(maybe 12") duct that feeds both the return in the kitchen as well as an adjoining bedroom. It attaches into a large square duct (8"x2'x 5 feet long) that branches between the two rooms. My thought was to remove the massive square and feed directly to the other room. My other thought would be to run a new duct directly to the outside.(opinions on that are welcome as well) I might post some images on photobucket to clarify.
To answer your questions: I would lose 1 of 4 returns so the amount it would lose would be at most 25%. The floor grills are 14"x12" for each of the returns. Pretty massive. As an aside, the return is currently covered by an area rug so its not getting a lot air moving through it to begin with. Regarding moving it: Possible, but would rather not since one of the goals is to create more than a 6' clearance in the basement which in turn would create more ductwork coming off the great metal octopus.
The duct size you mention is designed for 1,000 CFM worth of air. Removing 50% will take 500 CFM out of the picture. While the other three may take up the loss you may find your energy compsumption will go up and the capacity to heat or coor will go down if you do. You can either increase the size of the other ducts and grills to compensate for this, Best way. or do nothing. Worse way. You say your going to do some work in the basement to clean up the octopus and finish the basement? I would get a sheet metal contractor or a HVAC person in there to do this before you proceed. Undersized returns can cause adverse and somtimes unsafe conditions because of back drafting. As the furnace starves for air it will attempt to get it from any leakage within the ducts. If it pulls the air from the unfinished basement it can cause back drafting of the furnace sucking up CO and also pull radon gas out of the ground and into the home.
Posts: 1012 | Location: New Jersey | Registered: 31 January 2006
