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13 SEER on old Evap

Wow, someone has a great project ahead of them.It seem that someone found a airhandler that had the building built around it and stuck and its never coming out.

Your appoach is spot on.You will also find that in most cases the load on the evaporator will dictate what the expansion valve adjust the superheat too.

To offer some heads up...If this is a twin coil one stack on top of the other, beware of which coil is stage first.If not you will be chasing moisture issue.The bottom coil will be first stage.How is that drain pan by the way?

As far as the fan cycling and how much refrigerant that those condenser can stack would be a issue best address from the mfg that selling you the new condenser.
After all he needs to earn the sale just like we do.

You're a lucky man.I'll be out today running some gas pipe.Where summer?


    [email protected] Member Posts: 139
    13 SEER on old Evap

    Hi all,

    Now working at the local community college overseeing their hvac.

    Installed a 13 Seer 3 phase condensor the other day on a 25 year old evap coil. I know, I know, should not have done that!!

    But my question is.....If I install a OEM txv will that give me better suction pressure? If I remember correctly, the new evap are sized for the higher charge of the new condeser. But what about the txv? Is it designed for the lower head pressure? If I remember correctly, most txv's are designed for a 100 pound pressure drop. With the lower head pressures and lower ambients wouldn't that txv have to be sized differently? Going to wholesale house tomorrow to get low ambient controls for it. Looking for the kind that senses liq. line temp and cycles fan speed.

    This system is going to get new txv, solenoid, and driers. Oh by the way the coil is a dual circuit. Two 5 ton cond. on the one coil in the one air handler.

    Just thinking out loud, never hurts, but most people do look at you funny. LOL

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