Bought a condo for my daughter at college and it has a 3.5 Ton York Heat pump. Had it checked and the tech said it is nearing its 10 year life, yet working.
My question is if I should have to replace, since there is no gas, should I go back with a heat pump or just a high eff. full electric heater and condensor?
Suction pressure sounds OK to me but discharge sounds a bit low which may indicate an undercharge on a 8-10 SEER unit. I always add 10-20 deg F to the temp to get the pressure on a cool day if nothing else works. 83F in R22 =148 add 10 to 20 =158-168 psi. Impossible to tell w/o us being there and seeing the outdoor temp/humidity/cleanliness of coil/whether it was in the shade etc etc. Sounds OK to me. Ballparking never works well and we stopped recommending the beer can cold method of charging ACs years ago. Used to tell the newbies to keep adding freon until the suction line was cold and sweating like a beer can.:yes:
Suction pressure sounds OK to me but discharge sounds a bit low. I always add 10-20 deg F to the temp to get the pressure. 83F in R22 =148 add 10 to 20 =158-168 psi. Impossible to tell w/o us being there and seeing the outdoor temp/humidity/cleanliness of coil/whether it was in the shade etc etc. Sounds OK to me. Ballparking never works well and we stopped recommending the beer can cold method of charging ACs years ago. Used to tell the newbies to keep adding freon until the suction line was cold and sweating like a beer can.:yes:
I don't like those documents to much. There subcooling is based on the head pressure temp and are saying to add or remove gas on that. Don't go buy that SH target as well. I don't know where hose documents are from but there is better info out there.
In that link they are using the old rule of thumb for 10 SEER equipment. Which was close. But 6, 8, and 10 SEER was forgiving, 12 SEER and higher is not forgiving. So hopefully no one really uses that SC BS in that link.
Low SEER units didn't remove a lot of heat from the refrigerant, so they had to raise the sat temp real high above outdoor temp to get it to change state, and remain liquid all the way to the indoor metering device.
SC is only required to ensure a solid column of liquid to the metering device(for those that didn't know its purpose).
So to charging 13 seer or higher: calculate subcooling. Measure the high side pressure at the liquid-line service valve pressure tap. Using a pressure temperature chart, convert high side pressure to saturated temperature. Then simply subtract the liquid-line temperature from the saturation temperature of the refrigerant in the condenser to determine the subcooling.
The SC showing in the doc is ok to lower than 13 seer.
Subcooling increases efficiency a bit (on refrigerators they would solder the liquid line/capillary tube to the suction line to cool the liquid and increase efficiency) and it really is too keep a solid flow of liquid and no flash gas :nowhat I get on chili nites):yes: from getting to the orifice/metering device.
Hang in there JJ and ask good questions and you will build a database of fundamentals from each of the techs here.
Subcooling is easier I find as long as you have the right temperature conditions. Just simply get a temp probe on the liquid line out of the condenser and take your liquid line pressure and get the corresponding saturated temperature on your gauges.
Standard in 2001 for York from the factory would be a piston. If it has a TXV, then someone splurged and installed it in the field.
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