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sizing a Zoned system

I am working on a bid , three zone AC 13 seer single Attic system in the North East , high humidity area , designed with a 20* delta .. each zone is nearly equal ,16K ,16K & 17K or 4 ton system ... With a bypass, damper and duct temperature sensor... Would it be best to drop the size of the system and by how much per zone ?

Big Ed
I have enough experience to know , that I dont know it all


  • Techman
    Techman Member Posts: 2,144
    Zoned in

    Hi Big Ed, zoned systems have been around for years,some good and some not so good.Honeywell [Trol-a temp]has some good controls  ,so does EWC ,so does Durodyne. Robert C Ring,formerly of Trol-a- temp , is very smart concerning zoned systems. He reccomends  [on smaller ton systems,like 3t and lower]sizing each of the three trunks  to 2/3 of the total system CFM  or oversizing each trunk,and you donot need a bypass duct/damper this way.But different mfrg's have their own rules which do require the use of the bypass duct/damper.So check with the zone mfrg's guide lines and also the AC  mfrg's input. Rheem says yes to only a 50/50 sized two zoned system, and only with two speed compressors ,which means 16seer. I've seen a 4zone  3Ton setup,but it had a dead compressor also.
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