DIYbanter - View Single Post - hvac: variable speed, 2/1 stage, R410A/R22, 80/90% decisions

John Hines

(Todd H.) wrote:

3) Variable speed vs fixed speed fan.

caused by the transition causing the motor to run at higher speeds
for longer than it should--some mention perhaps of a sensor of
some sort? How do Carrier's variable speed motors work?

I dunno. I got a Lennox a couple of years ago, with the variable speed.
It works great, barely noticeable. I let it run all the time, so the air
circulates through the house and gets filtered.

The Frigidaire dealer was very pro-variable speed, although they
couldn't seem to explain to me my question about "what dictates
the speed the fan runs during a cycle? Is there a sensor? Is it
timed?" They told me a lot about dip switches for setting mins
and maxes, but never did manage to "get" that I wanted to know the
control algorithm for the fan speed so I could make sense of maybe
why they were all for variable while the Carrier guy was not.

For a SWAK I'd say its a combo of both. If the heat is on for more than
xxx seconds, increase the fan speed. When the furnace cools down, shut
it off.

4) Dual stage furnace vs single stage. The Carrier dealer, who'd
ruled out variable speed based on my duct configuration, said a
2-stage would bring me more comfort and evenness of heating temp.
The Frigidaire dealer wasn't pushing 2 stage since variable speed
addressed the comfort issue.

The only time I've seen the second stage heat kick on, was when they
tested it after the install. Unless you have wide swings, like setting
back the temp during the day or night, it should hardly run. Which is
good, cause it throws a LOT of heat in a hurry.

5) 13SEER vs 15SEER. If it only cost $300 more, would ya do it?
Another $300 gets me to 15SEER and quiet.

Sounds well worth it.

7) Do furnace and A/C simultaneously?

Yeah, have them do all the plumbing a duct work at once. Why have things
torn up twice?

Company #3, another larger place, comes tomorrow.

The Air Conditioning and Heating Company Inc . did my Trane install out
in the western suburbs

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