I agree with Noon-air. They should put in a high efficiency evap coil,
even if you're staying with R-22 refrigerant. You MUST replace the if
you're moving to R410. If the first company is an authorized dealer
for a name brand company, they could lose their dealership for
recommending a hair brained combination like that.

The second company is correct that you need to install a matching
coil. Most of the high efficiency coils are oversized and then use a
thermostatic expansion valve to squeeze the most efficiency out of
them. However, if that's the way you go, make sure the blower motor
can provide the increased airflow demanded by the oversized coil.
Otherwise you'll get freeze up in humid weather.

Bottom line is you want a matched system.

You also need to change out the line set for the new refrigerant.


On Tue, 06 May 2008 17:50:41 GMT, "
wrote:

My mom's 22 year old 4 Ton 10-seer Carrier A/C condenser is shot. Her
furnace is relatively new.

She wants to replace the old unt with a new Puron Carrier 4 ton condenser.

One HVAC company is saying that they do not install new evaporator coils
because it is unnecessary, and the efficiency will be around 12 or 13 if the
old coils are used with a 15 seer unit. They say they have never had a
problem with leaving the old evaporator coils in.

Another HVAC company is saying that it is important to install new coils
because the efficency won't be good, and also the unit will be under more
stress with the old coils and will likely only last for 4 years.

Which of the two is correct?

Thanks,

J.