Adding AC to exiting forced air furnace system?

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Old 10-18-20, 09:47 PM
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Adding AC to exiting forced air furnace system?

We are averaging more and more 80+degree days per year as time goes on and our ceiling fans just aren't cutting it as much anymore. We have relatively modern "PAYNE" forced air furnace system. The furnace is located in the garage near an external wall with plenty of space on the outside. Generally speaking is it possible to retrofit AC into the existing system? The duct work within the house was all re-done during a full remodel ~2 years ago.
 
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Old 10-18-20, 10:02 PM
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Most newer furnaces can take the addition of an A/C coil.
You'd need to contact your HVAC company as they'll need to calculate what size units are needed for the furnace as well as the unit outside. Some duct modification will also need to be done at the furnace for the coil.
 
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Old 10-19-20, 12:39 AM
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You won't need much cooling in your climate, with ASHRAE 1% about 82F. Give us the M/N of your furnace, the SF of your home, and year it was constructed. Did your renovations include new windows, additional insulation, etc?

The Payne will have the capability for adding AC, I'll try to tell you how much cooling you might need and whether your furnace can deliver the required airflow.
 
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Old 10-19-20, 02:56 PM
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How old is the Payne? Cast iron does crack with age and cycles. Might be time to consider a new 90+% furnace.
When I changed mine I considered both possibles. and decided that upgrading the heat would be a good idea.
 
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Old 10-19-20, 02:59 PM
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We have relatively modern "PAYNE" forced air furnace system.
I would say that is new enough to add A/C to it.
 
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Old 10-19-20, 03:24 PM
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Payne, Bryant and Carrier are essentially the same and I routinely spec'd Carrier in the 90's, so I'm sure it'll be OK for AC - especially with the light demand in that climate. My main concern is to determine whether the furnace can deliver a low enough airflow for the modest cooling requirement - As we've seen here, many contractors routinely oversize HVAC equipment.

As always, this comment is not to reflect on the many skilled, knowledgeable contractors, techs and installers out there - may their tribe increase!
 
 

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