fisher112
18-06-2009, 04:26 PM
I need some advice on my residential A/C system. I've been adjusting the R22 charge and I'm not getting the results I hoped for...I know you guys/gals get tons of these posts with inadequate data, so I've tried to cover most of those bases. Here's my system setup:
-New 13 SEER 2.0 TON R22 split system w/ fixed .67 orifice
My evap delta T is around 14F after the system runs for 30 min at the temps shown below, and I feel this is too low. Airflow through the coil is about 1000 CFM. All evap temp. measurements are taken within 5 feet of the evap. coil.
Outside Dry Bulb: 88F
Outside suction temp at condenser unit: 53
Suction Pressure: 82 PSI (49F Sat. Temp)
Liquid Pressure: 175 PSI (temp not recorded)
Inside Dry Bulb @ intake of evap: 70F
Inside Wet Bulb @ intake of evap: 67F
Inside Dry Bulb @ outlet of evap: 56F
Combined condenser fan & compresor amps: 6.5
From my unit's mfg chart, required superheat at these temps is 6 @ 90F outside temp and 10 @ 85F outside temp. This would indicate an overcharge condition (superheat too low). The problem is, I have recovered quite a bit of refrigerant with little to no change in system temps/pressures. When I initially draw down the charge, my suction temp rises to 60-62, but after the system settles down after 20-30 min, the temp goes back down to approx. 53 again. My compressor amps don't change more than a few tenths EVER, regardless of temp load. I think my orifice size is slightly large (should be closer to .61 instead of .67), but I'm thinking I should be able to get at least an 18 deg. delta across the evap in my case detailed above. Any suggestions? If I pull out slightly too much refrigerant, will I see evap temps drop to the point where freeze-up is a concern, or will my evap outlet temps rise (even less delta across coil)? I appreciate any insight.
Thanks,
Scott
-New 13 SEER 2.0 TON R22 split system w/ fixed .67 orifice
My evap delta T is around 14F after the system runs for 30 min at the temps shown below, and I feel this is too low. Airflow through the coil is about 1000 CFM. All evap temp. measurements are taken within 5 feet of the evap. coil.
Outside Dry Bulb: 88F
Outside suction temp at condenser unit: 53
Suction Pressure: 82 PSI (49F Sat. Temp)
Liquid Pressure: 175 PSI (temp not recorded)
Inside Dry Bulb @ intake of evap: 70F
Inside Wet Bulb @ intake of evap: 67F
Inside Dry Bulb @ outlet of evap: 56F
Combined condenser fan & compresor amps: 6.5
From my unit's mfg chart, required superheat at these temps is 6 @ 90F outside temp and 10 @ 85F outside temp. This would indicate an overcharge condition (superheat too low). The problem is, I have recovered quite a bit of refrigerant with little to no change in system temps/pressures. When I initially draw down the charge, my suction temp rises to 60-62, but after the system settles down after 20-30 min, the temp goes back down to approx. 53 again. My compressor amps don't change more than a few tenths EVER, regardless of temp load. I think my orifice size is slightly large (should be closer to .61 instead of .67), but I'm thinking I should be able to get at least an 18 deg. delta across the evap in my case detailed above. Any suggestions? If I pull out slightly too much refrigerant, will I see evap temps drop to the point where freeze-up is a concern, or will my evap outlet temps rise (even less delta across coil)? I appreciate any insight.
Thanks,
Scott