We just got a quote,to replace,our 33 year old Lennox central AC. We don’t run it much here in the SF Bay Area...maybe 15 to 20 days per year.
The HVAC company says the lower delta-T over the coil requires higher airflow for the same cooling load and we need to replace our return ducts in the crawl space as well as enlarge the two return air registers.
Anybody else heard this? We have some big problems replacing the return ducts.
If you live in an older house that originally only had central heating the ducts might be too small. Otherwise I would think you’d be okay. Since you don’t use the a/c that much, you might consider putting in a mini-split system.
“””... lower delta-T over the coil requires higher airflow for the same cooling load and we need to replace our return ducts...”””
That sounds counterintuitive. More air will absorb the cooling making the system run more. There has to be a balance. I may be presenting this wrong but it doesn’t make sense to me. Are they planning to change the blower to pull more air?
I’d be talking to someone else.
Just changed out my 22 y.o. Rheem unit. Went with a 3.5 ton unit with a 4 ton air handler. Cost 2200. Live in Florida air doesn’t run 15 to 20 days a year
Install a slightly larger condenser fan to compensate for the Delta T and call it good. The engineers will have your whole house rebuilt before summer is over.