Evaporator size

Old 07-28-03, 01:19 PM
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Evaporator size

I have a 3 ton condensor and "probably" a similar size evaporator. The evaporator "complete air handler" is ready for replacement (20+ years old... rusted...and dripping to auxiliary pan on a regular bases)

This system has never really worked well with July in house temps no lwer than 80-81 degrees.

Since the condensor is newer 1988, I thought I would have installed a 3.5 ton air handler to run with the 3 ton outside compressor. At a later date, when the condensor gives up the ghost, intall a 3.5 ton unit.

A couple of AC installers say this mis-match won't work and that I should by a complete new package. Also, they are not sure the ductwork could handle the extra half ton and want to run a complete system/duct check.

My question is will the 3.0 externat and 3.5 ton internal work (if the handler has a variable motor? or should I stick with the existing 3 ton package size with insuficient cooling power.
Old 07-28-03, 02:31 PM
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Your outdoor section with 15 years on it is near the end of it's life cycle anyway. My suggestion would be to return to sqaure one with a load calculation and ductwork layout. Then size the equipment from that. If you want to do the load analysis yourself, go to www.hvaccomputer.com For $49, you can buy a homeowner version of the same load calculation program that contractors use. They also have a forum you may find interesting.
Old 07-28-03, 04:21 PM
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bigjohn is right

15 years is a good life, especially if it is a heat pump.

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