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Posted by Zyp on June 1, 2008, 6:52 pm
Noon-Air wrote:
>> I just came back from my neighbors unit, its a 14 SEER Rheem R22
>> split HP. We walk our dogs together so he asked me if I could look
>> at it tomorrow. He said it wasn't cooling when he got home yesterday
>> so he shut off all night. I went & get my tools & checked it for him
>> today. Water
>> had been
>> coming out of his secondary overflow at the eave so I figured it was
>> probably the attic float switch. I used a wet vac on the secondary &
>> primary & the system started up O.K. Here's where things get screwy.
>> I checked the pressures & the system has fixed 25-30 degree
>> superheat(TXV) on the plate.
>
> I need model and serial numbers.
>
>> According to the chart the head pressures were right on
>> the money.
>> SP - 55 psi
>> HP - 225 psi
>> SH - 27 deg.
>> SC - 20 deg.
>> 86 DB outside temp
>> 80 DB inside temp
>>
>> Temp across indoor coil 12 deg.
>>
>> I originally thought the charge was low but I always check the unit
>> specs when available first.
>> Any other unit I would say would have a restriction
>> with high SH & SC but I've never seen a TXV that calls for such high
>> SH.
>
> Something is not right.. need model and serial numbers.
>
>> It doesn't even have a subcooling reference at all.
>> Its pouring water out of the drain so its obviously doing some
>> dehumidifying. I'm going back to check in the morning when I'll
>> actually feel like working but curious if any one familiar with
>> Rheem has ever run into this funky TXV 25-30 deg. SH spec. on a
>> residential unit.
>
> What are the model numbers for the heat pump and the air handler? The
> coil model number would be good too.
>
> As a rule, with Rheem stuff, you want 10 - 14 degrees of subcooling.
>
> My first impression is that its overcharged....and there may be an
> airflow restriction to complicate matters, and until I know what the
> model numbers are, I really can't tell you much else.
Superheat's too high for low air flow. I'm thinking the screen at the TXV
is clogged or semi - clogged. Seems like the condenser's back up [high
sub-cool] and the evaporator is dry [not enough refrigerant]. low
performance [low TD on evap.] is also evidence that there's not enough
refrigerant flow.
You should have a higher suction with the indoor temp. @ 80 deg., and a 10 -
14 deg superheat.
Check your TXV inlet screen.
--
Zyp
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