Size of Heat Pump versus Size of Air Handler

[sthomas]

This may seem like a stupid question but does the size of the air handler need to match the size of a heating/cooing unit? I have a 3.5 ton carrier heat pump system and 2500 sq foot home (500 feet added recently with duct work complete) am being advised to go to 4 ton unit. Do I have to replace the air handler as well?

[Milk man]

I would say yes.

I would tell you yes if it was a Lennox.

Your airhandler may be rated to work with the bigger outdoor unit all ready.

Post it's model number.

[comfortdoc]

Depends on the age and model. If it is sized for a 10 SEER system you will likely need to replace it.

Were proper Man J calculations done to determine size needed? If not it should be done before psending money on new equipment. Your money may be better spent on lowering the heat loss/gain of the building instead of increasing system size.

[sthomas]

Thanks for the reply! The model number is FA4ANF042. This was replaced about 6 years ago. The Carrier heat pump that I have now is 3.5 TON and has been going strong since it's inception in 1985! So I know I'll be needing to replace. It has a slow leak of the freon. Thanks again!

[sthomas]

Am reposting this as I never got an answer??? Can you advise?

Thanks for the help.

[drwiley]

It's a 3.5 ton air handler. Chances are it well need to be changed out as well.

[hivacer]

It will need to be changed out because the coil in the air handler is undersized. The blower may work with the new heat pump, but would have to see specs to know for sure.

One possibility would be changing the coil in the air handler, again, would have to see it. Replacing the coil in an air handler isnt always possible.

[lynn comstock]

A 20% addition may not add significant load to a home. Depends on construction. A proper professional heat load calculation is needed to correctly size a system.

It is common to falsely assume that a warm area of a home will be fixed by upsizing the unit. A warm (or cold area) of the home occurs when the duct system does not deliver enough air to cool (or heat) that area sufficiently. If your current unit is cycling on the hottest days in the afternoon, you definitely do NOT need a bigger unit.

[swagging tool]

was that 500 sq feet you added on a sun room?

[dash]

Originally posted by sthomas
This may seem like a stupid question but does the size of the air handler need to match the size of a heating/cooing unit? I have a 3.5 ton carrier heat pump system and 2500 sq foot home (500 feet added recently with duct work complete) am being advised to go to 4 ton unit. Do I have to replace the air handler as well?


First if the old 3.5 ton worked fine,don't go to 4 tons.

If you go to 4,you'll need a 4 ton air handler as a minmum.

Load calc.,Mnaul J,is very advisable,along with Manuals,S and D,so the equipment will sized(MJ),and selected(MS)corectly ,and the ducts (MD) will be correct for each room.