Just an uneducated consumer with a SEER 21 AC

[kspencer]

Our AC broke and my mother was really cranky in the hot humidity of VA. So she just wanted to get something into the house and get cool again. I sent her a ton of links to ACCA website, NATE certification website, and printed off the checklist for a manual J installation so that she could make sure the contractor was doing it right. But i dont know if he did a load calculation or not. He gave us a Carrier unit, 21 SEER that jumps from a 2 ton to a 3 ton depending on the work it needs to do to stay cool. Now that we have this super piece of equipment, what do i need to do to make sure that it is working as efficiently as possible? What about mini-duct air distribution? because i am sure we are losing a lot in old ductwork. Did we just waste a ton of money?

[phbsales]

kspencer, was it just the a/c that was replaced, or did your contractor replace the furnace (air handler) as well?

Did the contractor do a load calculation before the equipment was quoted?

If the load was properly calculated, all you need to do is have an HVAC professional perform semi-annual preventative maintenance which will include checking airflow, refrigerant pressures, condenser coil cleaning (and evap coil if necessary), among 20 - 30 other items (depending on contractor). All you really need to do is change the filters regularly and set the thermostat to an appropriate setting (htg- 66 to 70 deg F., cooling 72-78 deg F.).

[kspencer]

thanks...too bad i work all day so my mother was the one to deal with the contractors. yes it was just the ac, but i have not clue if they did a load calculation, and i dont think my mother does either. But it can change from a 2 ton to a 3 ton, so wouldnt that pretty much cover it? my house is probably 2,500 square ft...is it possible to have a system that is too good?

[beenthere]

What size was you old A/C.
It was just the A/C, did they replace the idoor section also.

[udarrell]

thanks...too bad i work all day so my mother was the one to deal with the contractors. yes it was just the ac, but i have not clue if they did a load calculation, and i dont think my mother does either. But it can change from a 2 ton to a 3 ton, so wouldnt that pretty much cover it? my house is probably 2,500 square ft...is it possible to have a system that is too good?

A 21-SEER system is awful high.
If you deal with high humidity, a lower EER & SEER might have been a better match for those conditions.

How do you think it is doing?

The ductwork & air handler's airflow are extremely important.

TROUBLE SHOOTING DATA
Age a unit & SEER Rating ________
Square Footage of home & major city near you __________
Out-Door temperature: _____________
Outdoor condenser’s DB discharge-air-temperature _____
In-Door temp DB and WB: ___________
Total-ESP/ air flow in CFM: _____________
Return air temp DB and, WB, or %RH: ____________
Supply air temp DB and, WB, or %RH: ____________
Which stage was it operating in with above data _______

My advice: get a low cost humidity gage at a local hardware store & see what the percentage-RH is in your home, I can cross-reference that to the wet bulb depression.

Just click the "Quote" button & fill in all the questions you can.

Then, perhaps we can provide a ballpark opinion on what it is going on.

[phbsales]

At 2500 square feet, I would be concerned about the system being too small and not about being too good. Double check the square footage of your home. I did a quick load calc. based on only square footage (not being able to see about windows, insulation, age of home for air infiltration purposes).

beenthere also asked what size your old a/c was. It would help.

[RyanHughes]

It's better if the indoor section is variable speed for that A/C... What's the indoor model number(s)?