Replyfirst verify the air flow. If it is not within specs, that will throw the whole system out of whack. Do you know what size piston is in it, or did they install the TXV kit?
Professional Member*
Just got through with a service call on a Goodman heat pump system. Customer has lived in house about a year and has had someone else servicing the system. They put UV dye in the system and told the customer that "If they couldn't find a leak, there was no charge but if they did find a leak the charge would be $xxx.xx for the dye." They didn't find any leak! The customer called me because the hp wasn't operating --bug in contactor!!
My question is about the performance of this system at these conditions: ODT 85*, RAT 78*; LP 82 psi, HP 205 psi and SH was 9*, indoor drop was 14-15*. I recovered 1.5 lbs R-22. The LP was 77.4 psi, HP 199 psi, SH 10* indoor drop was still 14-15*.
The equiptment is: HP: CPLT42-1B, SN: 0501xxxxxx, AHU: ARUF049-00A-1B, SN: 0509xxxxxx. The duct system is typical flex duct runs in a radial configuration with 1300 CFM (at best) of supply openings. The return is a 24"x24" filter grille through wall into return cavity below AHU. The indoor blower has a slight "buffeting" noise (high static?--I didn't check SP).
I would have thought that by removing 1.5 lbs. of refrigerant that the SH would have increased more than 1*. The chart on the HP indicated that the SH should be 10-15* depending on indoor air temp. Also, I thought that the indoor split would have increased closer to 20*.
Is this AHU a match for this HP? If so, what is the correct piston in the AHU for this HP? Is the system possibly still slightly overcharged? The indoor temperature did drop 2-3* while I was working on the system.
Professional Member*
first verify the air flow. If it is not within specs, that will throw the whole system out of whack. Do you know what size piston is in it, or did they install the TXV kit?
Professional Member*
Didn't check for TXV. Most of the Goodman installers in this area don't know what a TXV is!!!
Professional Member*
I can give you an educated guess that the correct piston is a 80-83ish.
And yes you will likely find the 4ton piston installed.
Global Moderator
This unit is a match and the piston is listed as .078 - .082.Originally Posted by Bill Lee
Any chance of doing a static pressure test on this unit to see what airflow you really do have?
What was the subcooling?
What was the indoor WB?
Instead of learning the tricks of the trade, learn the trade.
Professional Member*
What will SC tell you with piston metering? Didn't check WB indoor temp.
Global Moderator
It's just another piece of the puzzle.
With a piston metering device you do charge by superheat, but knowing the subcooing will give you more information about it possibly being over/ undercharged, or if you have a restriction.
All of this is assuming the airflow is correct.
Instead of learning the tricks of the trade, learn the trade.
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