I have a Lennox 5 ton A/C unit that has had 2 past leaks (Unit is 10 years old and we live in Phoenix). After not cooling below 77 degrees, our usual A/C repairman came out last week and suggested a new unit even though he couldn't isolate the leak this time. He charged the Freon and we blow cold again but its just a matter of time at 110 degrees outside. He sent an estimate for a new Day&Night 5 ton 13 SEER unit. My questions:1. Is it OK to install a Day&Night unit with a Lennox air handler? 2. I know that Lennox can be a pain but if its OK to mix and match, should I try another unit instead of Day&Night? Thanks

Mixing is OK,, there not many units out there that are matched sets,, just make sure they replace evaporater coil to match the condenser unit, also line set, if done right the leaks should be no more,, the brand of equipment all are about the same, the installation is very important,, as about a unit with a good warranty, some have 10 years all parts

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Originally Posted by wmproop

mixing is ok,,,,there not many units out there that are matched sets,,,just make sure they replace evaporater coil to match the condenser unit,,also line set,,if done right the leaks should be no more,,,,,,the brand of equipment all are about the same,,the installation is very important,,,,as about a unit with a good warrenty,,some have 10 years all parts

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Make sure you have the inside coil changed like was mentioned before. Below is just one of the reasons.




Nominal two Ton System.

A heat pump outdoor unit manufactured in 2003 took a 125oz. Charge of R-22.
A heat pump outdoor unit manufactured in 2007 took a 200oz. Charge of R-22.

On the heat pump outdoor unit alone there is a volume mis-match of 1.6.
Meaning, the volume of Refrigerant held in a unit manufactured in 2007
Is 1.6 times that of a unit manufactured in 2003.

On an indoor coil manufactured in 2003 the face area of a
Coil was 3.8 sq. ft. at 13 fin/inch, 3 rows deep.
On an indoor coil manufactured in 2007 the face area of a
Coil was 4.38 sq. ft. at 14 fin/inch, 3 rows deep.


Also see attached