When selecting the air conditioning and heating equipment needed to provide the comfort and energy savings that is listed on either the condensing unit [outside unit] or the airhandler [inside unit] the two pieces need to be matched per the manufactures recommendations.If not you will not get the performance you were told. That is SEER rating or BTU rating.
A study done by the Alabama Energy Commission concluded these results:
1. Up to 40% reduced capacity [BTU’s] in cooling meaning system may not be able to keep up with thermostat setting.
2. Up to 8% reduced capacity in heating resulting in strip heat coming on earlier.
3. Up to 40% reduced efficiency in cooling resulting in higher power bills.
4. Up to 60% reduced efficiency in heating resulting in higher power bills.
5. System charging becomes critical since the charge might seem correct for one condition but flood on another.
6. A thermostatic expansion valve will not solve the charge problem for all cases since the sensible heat and subcooling can change dramatically with conditions.
All off these situations will result in numerous service calls and most likely the only way to resolve it is to replace one of the units to match the new piece of equipment.
The reason this has become so critical now is the high efficiencies of the new piece of equipment that everyone has to install. So when you want or your contractor suggests changing out a single piece of equipment don’t do it! It does not match your old unit. So when you purchase the equipment make sure the model and serial number is on the contract so you can check it. And like we’ve said in our other reports, make sure the contractor pulls a permit for your own protection.
P.S. Remember! R22 refrigerant is no longer allowed in New Equipment. R410 is the new refrigerant – another reason to be concerned about replacing one piece in a system and winding up with a bad mismatch.