Are 14 inch return ducts big enough for 4-ton heat pump?
gover
15 years ago
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Tinmantu
15 years agogover
15 years agoRelated Discussions
Heat Pump Ductwork/Trane XR14
Comments (2)Also just an owner/DIYer, although I have a day job as an engineer. Garyg has it right on rigid duct being preferable to flex. If you can, you want to limit flex duct runs to the 5 feet or so at the end of each run. I don't have any experience with rigid fiberglass duct. I'd also go for several more returns to get full coverage. Since you're investing in a new system, you want that system sized properly. The gold standard for sizing is ACCA Manual J for the cooling equipment and Manual D for ductwork. I'd be concerned about anyone who was just going on square footage to determine AC tonnage. The other thing I'd want done is a duct blaster test on the installed system. Basically this determines how leaky the ductwork is. If the contractor has the capability to DIY the test, that'd be a great sign. If not, there are 3rd party testers who'll do it for a couple hundred bucks. But, and this is a big one, if the contractor hasn't had his ducts blown before, I'd have him talk to the tester before starting to understand what kind of extra steps he may need to take that he isn't accustomed to. A good leakage rate for a newly-installed duct system is 0.05 cfm/sq ft- that's cubic feet per minute per square foot of your conditioned space. My perspective is that we used a contractor (existing house, new system in attic) who said, "yeah, I put in tightly sealed duct." It tested at over 1-ton of leakage on a 3.5-ton system. Even though I thought we'd made it clear up front what we expected (and that he had the opportunity to adjust pricing accordingly), it turned into a big mess. And I inherited the job of going back and finding the leaks and patching them. If I had it to do over, I'd still want the system sized properly and installed with minimal leakage. And I'd have hired someone else. Here are some resources: http://www.southface.org/web/resources&services/publications/factsheets/22blowdoor.pdf http://www.southface.org/web/resources&services/publications/factsheets/2duct_q&a.pdf http://www.southface.org/web/resources&services/publications/technical_bulletins/HCES-HVAC-selection%2002-779.pdf http://www.southface.org/web/resources&services/publications/technical_bulletins/DD-Air-sys-design%2002-0782.pdf http://www.southface.org/web/resources&services/publications/technical_bulletins/DIS-Air-sys-install%2003-0783.pdf...See MoreReturn air requirements for a 4 ton unit?
Comments (6)For the people with multiple room returns calculating return air square inches do not stop at the duct size rather floor joist config and register size. I had minimal register sizing but only had approx 2x5" holes cut in the floor for the air to pass through to the return duct, 6 of them for a 3 ton system. I added 2 more and increased the size of the existing to approx 3x12" each. I did have 2 6x30 vents and 2 6x14" vents and added one more return duct 6x30. I had 60sq in of open return hole area in the floor with 528 sq in of return register size. I increased the open hole area to 288 sq inches with a return area of 708. The return ducts are panned floor joists so there is a ton of room there. I had a nightmare to rebuild and seal to get it set up and sized correctly. Just keep in mind... its not all about the registers on the wall or in the ceiling....See MoreHeat Pump Return Duct
Comments (1)Good grief the FIRST and only thing you need to be concerned with ( yes I know this is a old thread/posts but I have to respond to this ) is what in the world is a 4 ton doing in a 1300 sq ft double wide???????????? If you dont have moisture problems your house must be blessed by god himself. That unit is ENTIRELY too large for your home....See MoreTrane 2 Ton Heat Pump - high indoor humidity
Comments (16)Changing my fan speed last year (it was set on the highest) combined with a much friendlier weather pattern this year. My humidity is in the 48-52 range. Last year I had it in the high 60's! Last year the winter/spring were incredibly wet. Even my basement has lower humidity this year, so I think the weather had a lot to do with it. I have conventional ac, but it was ME who figured out that the wire that was hooked up was for the highest fan speed when ac was in high (I have multi speed, not variable speed). I told the tech that I thought the wires should be switched because my fan was set too high, my blower is sized for my heater-which is bigger than my ac. FIgured it out by reading this board and learning that too fast cfm means less time for moisture to be removed, then I READ THE MANUAL. Much like the OP has done. I showed the tech (the experts they sent out when the first guy had no clue). This year my doors aren't sticking. I think this is the least they've ever stuck (in the summer). Sometimes I think it's TOO dry (according to my throat/nose in the morning) but it might be allergies. Yes, Homeowners shouldn't mess with things, but if we do we need to be sure to document what the original settings were so we can fix our fix if it doesn't work. (take a photo, or draw a diagram) Some of the charts and diagrams are pretty easy to understand. I wouldn't touch anything if I weren't certain. My humididty might be even lower if we kept our garage doors closed all day and if we shut the front door. We let the dog look out the storm door, but it's a pretty good seal....See Morezl700
15 years agogover
15 years agofunnycide
15 years agogover
15 years agofunnycide
15 years agozl700
15 years agogover
15 years agopyramidhvacr
15 years agogover
15 years agozl700
15 years ago
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