Bad Return Air Duct in Basement
vinamra bhatnagar
2 years ago
last modified: 2 years ago
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Comments (8)
vinamra bhatnagar
2 years agoAustin Air Companie
2 years agolast modified: 2 years agoRelated Discussions
replacing a return air duct
Comments (2)you need to go back to the main trunk line. air travels the path of least resistance. if you tap off of another return line and one is shorter than the other the air will mostly be drawn from that one. not to mention you are restricted by the size of the return run you are taking it from. it will work better coming off of main trunk line....See MoreCalculating return air grille sizes and duct work
Comments (1)First, I figured you would not answer any questions and about 8 years ago I did have a blower test and ESP test done and the manual J performed and none of them would show me the results except to say, I needed a 4.5 ton unit which is on the fence, right? And all said they would have used the same duct work and the blower test was 34 out of like 50 (whatever that value is, I just don't remember). He said not bad and usually sees a lot worse, but could be better and they wanted to gut my duct system and go to all metal duct and both companies pricing was about $6,000 to $7,000 again, about 8 years ago. I had other estimates too, but I don't trust most A/C companies around here as I used to do the repair business years ago and it was mainly window units back then and I know how this business overall operates and you and others online are the exception rather than the rule in residential work. Which is great, but surely you know how bad it is? It is way too competitive and other things I know, I'll just say is very embarrassing to say the least. So, as I do the manual J and D calculations myself I am coming up with between 4 and 4.5 ton system, which you are right, so I see it is going to be oversized. But, I will say we had upper 80 degree days last week and the humiditiy was in the mid 40 percent range in my home as did my 4 ton unit performed and was still comfortable. But, I understand the tighter I make the system, doing as designed will bring the temperature down more quickly and will not be able to control the humidity as well and may become more uncomfortable and cycle more often making it less efficient. Your link is what has made me do what I am doing so far and I thank you for sharing some of your knowledge to the public, I wished I had seen it before I made this move. I know this is not a good excuse, but we had two 14,000 btu portable units in the house this summer and still couldn't keep the temperatue in the house from climbing to 80 degrees during peak outdoor temperature and the central system still would run until midnight before it would shut down briefly. I understand between the leaks and being undersized on return I was losing ground from day one as we bought this model home new. It just seems these portable units would have helped a little bit in keeping the temperature reasonable in our home. I even had a third unit ready to install, but we sweated it out through the end of the cooling season and so, how many would it have taken, 5, 6, or 7 units? Thanks....See Morecold air return vent in basement
Comments (3)You'll hear a lot of debate about this one - some will say you can't do it without calculating a Manual J etc but the reality is there's a lot of boilerplate hvac systems, at least where I am in Canada. I have two returns in the upper floor of my house only a couple of metres apart, and none in the finished basement and none in any of the bedrooms, which I've been told is an 'impossibility' - well here in Canada, it's not and the system works well enough - the master bedroom is a bit cooler with the door closed, but it's above a poorly insulated garage. I see a lot of basements with the return in the ceiling. Warm air does rise, though, and in the summer you might want some of that cooler air in the basement circulating upstairs, so I'm planning to do exactly what you mentioned, put the return near the floor, backing onto the furnace room. If there was some sort of big issue with changed airflow, you could probably block off an equivalent of the downstairs return vent in the upper return, to equalise the air flow, but to this layperson, the SUPPLY of cold air is not as much of an issue if you're not getting cavitation (a vacuum effect because the pump isn't able to suck in as much air as it's trying to deliver.) Take some temperature readings over a few hours in different spots in the house, and make note whether the furnace is running a lot more than it was previously. The 'duct work' typically is either the space between floor joists or a boxed duct around the same size, or, running down the wall, typical stud wall spacing, 16." That's what I see here in British Columbia, again, I'm not an HVAC tech. Don't go excessively large. If you go through the furnace room wall you won't need much in the way of ducting and if you need to you can use thermopan (silver faced cardboard) instead of drywall or OSB to form the 'duct' from the floor up to the return (make sure you cut into the return, not the warm air section and make triple sure you're not going to damage any wires, gas lines, a/c lines etc. As for the return, the standard size grille is about the width of the space between studs I guess so around 16?" If you need to tweak it, you can block sections of it or the upstairs one inside under the grille if you need to. If you're careful, you're not going to damage anything irrevocably....See MoreReturn Air Duct placement 2 story great room DESIGN DILEMMA!
Comments (22)Iowa, you must have a basement and returns could be "easier" to relocate. Hopefully, those are just returning the CFM required for that room and not the entire house. Be aware that with 18' walls there will be blocking somewhere above those vents or something framing in from whatever's on the other side of that wall which might prevent you from raising the vents up higher (at least easily). A well-advised HVAC designer (not equipment tech) can review the size of both stud space openings through the floor for each vent and possibly find another location/combine a couple if you can meet the CFM flow. The location to the left of FP is too close to the floor register IMO anyway....See Moremike_home
2 years agovinamra bhatnagar
2 years agomike_home
2 years agovinamra bhatnagar
2 years agoCoolAir Inc.
2 years ago
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