Size matching of evaporator and condenser

**Gene South** · 10-28-2011, 08:16 AM

During a recent inspection of a 1980's home that had a new HVAC system installed, I noticed the new condenser was labled as 3.5 tons and the new evaporator was labled as 4 tons. Both were Lennox units and the condenser was configured as a heat pump. The system appear to be functoning fine. Do any of you see this often when the evaporator and condenser are not size-matched? I am not even sure this is a problem or not, that is why I am asking.

PS, I know some might say this goes beyond the scope of a general inspection, etc, etc, however I am still curious about it.

Similar Threads:

**Rod Butler** · 10-28-2011, 12:56 PM

Gene, I may be a little old school but that used to be routine when selecting AC equipment. Slightly over sizing the evaporator gave a bit better performance, a way to bridge the gap in equipment sizes.

Of course if it were the other way around you would have a problem with freezing the coil.

How were you able to determine the size of the coil?

Bob Spermo · 10-28-2011, 01:13 PM

Probably OK for the coil to be a 1/2 ton larger. However, I would be very careful about commenting on compatability between the condenser and the evaporator coil unless I had researched what the manuafacturers' said. The only way to assure compatability in by using the manuafcaturers' data sheets.

**Vern Heiler** · 10-28-2011, 03:08 PM

Gene, as others have said, it is not uncommon to have size difference but needs to be acceptable configuration by mfg. specs.

When referring to a heat-pump, it is better to use "indoor unit" and "outdoor unit" as they are both condenser and evaporator.

**Gene South** · 10-28-2011, 04:17 PM

Hi Rob, Vern, and Bob. Thanks for the good input and it is consistent with what I guessed. I do understand that on a heat pump system the term condenser and evaporator can be used for either unit, but I did not put that in the post because I figured everyone would know what I meant and I wanted to stay "on-topic". You know on this forum,.... at any moment,.... a topic can spin off into another whole discussion about heat pumps or some other topic. HA. But to clarify your questions, the "indoor" unit was 4 ton and the outside unit was 3.5 ton. I decoded the model number to make that determination, to the best of my humble ability.

Gene

David Bell · 10-30-2011, 05:47 PM

Larger evap coils are often the only way to reach intended SEER ratings. It is recommended by every manufacturer I have dealt with so far because it keeps thier equipment efficiencies where the government wants to see them.

**Bill Hetner** · 10-31-2011, 12:27 AM

is there any postings at the site as to who did the install? you could call them or ask some hvac installers in the area what they think too. they would know more about it, also it might have been a case of what they had in stock and wanted to move out too. what matters most is does it work and does it work good enought to do the job right for the house.

**Joseph Peake** · 10-31-2011, 02:22 AM

David's answer matches what I was told when I purchased new equipment for my home. Better SEER and better dehumidification.

**Sal Castro** · 10-31-2011, 12:42 PM

A problem we recently found was a builder/contractor who tried to mix a new R-417a condenser and an older R-22 air handler. That needs to be monitored as well.

David Bell · 10-31-2011, 04:41 PM

Originally Posted by Sal Castro

A problem we recently found was a builder/contractor who tried to mix a new R-417a condenser and an older R-22 air handler. That needs to be monitored as well.

Most 410-A units can be interchanged with r-22 coils with a txv change. A flush of the system is required to remove any oil that is not compatible.