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Cool air coming through floor registers with unit off

2K views 9 replies 5 participants last post by  Ridgerunner 
#1 ·
Hi All...New here and hope you can help!
I have a 20 yr old Lennox unit (heat pump) and it works just fine...problem is when the unit is off, cool air comes in through the floor registers...all of them.
I went into the crawl space and taped with foil any ducts that the tape looked worn or seperated although I didn't check the ductwork to the registers as all are wrapped in insulation but did check the connections to the main duct. Also closed off all foundation vent openings. Still getting cold air through registers...did I miss something or could it be something other than ductwork?
 
#2 ·
Where is the air filter? If its in a bracket external to the furnace, is it sealed. look to see if you have a fresh air intake pipe.
 
#6 ·
sealing

Take the register off the floor and check to make sure the boots are properly sealed there should be no gaps between the supply boot and the subfloor you may also use a flash light and look down into the supply vent to make sure there are no broken elbows or joints
 
#7 ·
I will check the registers just to make sure...it's just strange that this just happened all at once and at all the registers...right now I have all the registers taped off to keep the cold air out and I haven't turned my heat on except to check and make sure the unit was running OK. Just don't want to be heating the great outdoors when I do turn it on...like soon since we're going to hit 32 tonight.
Thanks for all of your responses
 
#10 ·
I found it!! An access panel on the unit was loose...looks to be the coils...it had been duct taped on with no screws holding it and I could feel cold air seeping around it...removed the old tape and took it off and air came blowing out like a gale...cleaned coils and put in new screws and foil taped it up and that stopped the air through the registers...don't really know what I did but it worked...once that done I took out all floor registers and taped ducts there too just as a extra precaution....turned the unit on and let it run for about an hour and shut it down...whoo hoo no more air leak at the registers! Think I'm good to go for winter!
Thank you all for your help and suggestions! Really do appreciate it!
 
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