I've gotten different bids and need some of your experience:
1650sf. L shaped wood ranch house in the sun in Wisconsin (humid and very warm (90s + that sun beating down) but not extended hot) mid 1960s vintage not really updated so the house isn't tight or well insulated, but OK for us regular folk.
Existing unit is 20"w x 40"d 50"h ; plenums are 18"w x 14"d. Ducts branch "e" and "w" from the unit each one 8x14 and from there they go into 8 different 6" pipes to the registers. 7x14 returns (again, two joining back to the furnace.
It's 100k in, 80k output that still works (yea! built in the USA around '70) and the AC looks to have an almost 3T condenser that I don't know ever kept up it's end of the bargain on the hottest days? But did dehumidify. Just ran and ran and need the evening to actually drop it down. I tend to think it was operable but not 100% until recently when it appears to have sprung a leak and R22 repairs on this vintage is probably not a good idea. I could just do the AC but who knows how the hamster wheel fan will operate if I just did a coil and condenser without some tweaking?
I'm probably staying 80% so I don't need to deal with chimney lining (for water heater), etc.
The AC bids have come back kind of all over the place some guys say each ton covers 600, 800 and 1000s.f. so I've got bids for 2T, 2.5T and 2.5 with a 3T coil.
Some (80%) heat came in at 60k, 80k, 88k but the AC is what troubles me most. From what I've read, it seems like airflow speed is quite possibly the most important part. Should I be looking to do 400CFM for each ton of AC or do I overshoot it? I believe I saw 100-130CFM per raw BTU for heat so that would be 800-1,040 CFM in winter.
Part of me says 2T, part says 2T with 2.5T coil and part says just 2.5T but getting the proper air movement is questionable: too much or too little. I've spec'd out different brands and their tentative CFMs ranging from 750' to 1200' and 845-1900' on others. but they steps in between (as you know) are kind of unevenly spaced.
Seems like the larger units (21" wide) that would be closer to my duct plenums are usually suited more for 3-4T whereas the 17.5" is more in the 2-3T arena which might be closer to our needs but certainly not vs the existing/dated stuff. Humidity is definitely the concern as I get that a larger AC will chill more quickly but I can't tell which way to go?
If you guys have some kind words, I'd appreciate your help.
1650sf. L shaped wood ranch house in the sun in Wisconsin (humid and very warm (90s + that sun beating down) but not extended hot) mid 1960s vintage not really updated so the house isn't tight or well insulated, but OK for us regular folk.
Existing unit is 20"w x 40"d 50"h ; plenums are 18"w x 14"d. Ducts branch "e" and "w" from the unit each one 8x14 and from there they go into 8 different 6" pipes to the registers. 7x14 returns (again, two joining back to the furnace.
It's 100k in, 80k output that still works (yea! built in the USA around '70) and the AC looks to have an almost 3T condenser that I don't know ever kept up it's end of the bargain on the hottest days? But did dehumidify. Just ran and ran and need the evening to actually drop it down. I tend to think it was operable but not 100% until recently when it appears to have sprung a leak and R22 repairs on this vintage is probably not a good idea. I could just do the AC but who knows how the hamster wheel fan will operate if I just did a coil and condenser without some tweaking?
I'm probably staying 80% so I don't need to deal with chimney lining (for water heater), etc.
The AC bids have come back kind of all over the place some guys say each ton covers 600, 800 and 1000s.f. so I've got bids for 2T, 2.5T and 2.5 with a 3T coil.
Some (80%) heat came in at 60k, 80k, 88k but the AC is what troubles me most. From what I've read, it seems like airflow speed is quite possibly the most important part. Should I be looking to do 400CFM for each ton of AC or do I overshoot it? I believe I saw 100-130CFM per raw BTU for heat so that would be 800-1,040 CFM in winter.
Part of me says 2T, part says 2T with 2.5T coil and part says just 2.5T but getting the proper air movement is questionable: too much or too little. I've spec'd out different brands and their tentative CFMs ranging from 750' to 1200' and 845-1900' on others. but they steps in between (as you know) are kind of unevenly spaced.
Seems like the larger units (21" wide) that would be closer to my duct plenums are usually suited more for 3-4T whereas the 17.5" is more in the 2-3T arena which might be closer to our needs but certainly not vs the existing/dated stuff. Humidity is definitely the concern as I get that a larger AC will chill more quickly but I can't tell which way to go?
If you guys have some kind words, I'd appreciate your help.
source https://hvac-talk.com/vbb/threads/2238767-Time-to-upgrade-the-50y-o-stuff?goto=newpost
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