I have a Rheem 3 ton air handler and a 2 1/2 ton condensing unit - a 14 degree Delta T. Ambient temperature 85 degrees, suction pressure 70, head 210, txb valve, discharge temp high side, 158 degrees, exiting cu coil 101 degrees, entering txb 96 degrees, vapor line exiting evaporator coil 67.5 degrees. Before service port 71.2 degrees, indoor wet bulb temp is 68, copper size 3/8''/3/4'', overall copper run is 25'.
Why is there a 13 degree Delta T?
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Re: 13 degree Delta T
I assume r-22 refrigerant by the pressure... you have a saturate temperature of approximately 41 degree and 71 degrees at the service port this equates to a 30 degree superheat. a condenser saturation temperature of 105 degrees and since the liquid line temp at the service valve is not given only the enterin indoor coil on the liquid line a 96 degree temperature this would equate to a subcooling temperatureof about nine degrees. You have too high of a superheat reading. verify that the bulb for the txv is correctly positioned and insulated. if it is then you need to remove the bulb from the suction line, hold it in your hand to warm it up and see if the superheat changes. you could also have issues with your ductwork. If the supply temperture is around 50-55 degrees then the unit is doing all it can.. Check the txv and the ductwork as the subcooling indicates that the condenser side is doing it's job, but the superheat readings indicate that you are starving the evaporator..
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A heat pump on the optimal heating day (about 50 degrees ambient) will only deliver approximately 85 degree air as compared to 125 degree air from a fossil fueled furnace. The colder the outdoor air is the less heat there is available to be transferred to the living space. At 30 degrees, the heat transfer capability is getting close to negligible meaning the run cycles will be approaching continuous and eventually as the heat pump along cannot maintain setpoint, the outdoor stat or stats will bring on auxilliary heat in the air handler.
If your ambient temp is below the 'balance point' of the heat pump, the house temp will drop a little lower and most times energize the heat strips through the outdoor t-stat. Your outdoor stat could be set too low for the heat pump to carry the structure all the way down to the balance point so when you turn it off and back on, the lower indoor temp automatically brings on the heat pump plus a heat strip or two, thus the warmer air. Second stage on the stat satisfies due to the heat strip, drops them out of the circuit and the heat pump is left running on first stage heat delivering the perceived cold air.
Your outdoor stat could also be not functioning correctly and not allowing the heaters to come on until the system is turned back on reestablishing the two stage call for heat.
Tons of possibilities and not enough room to list....
It sounds like you are low on charge. I think you have a thermostatic expansion valve and you need to check the subcooling, you should have 12 to 15 degrees at 95. At 95 degrees your head should be about 280# for a 12 or 13 SEER unit or higher depending on the effeciency. At 78 to 80 degrees indoor depending on the humidity, that is normal. The valve will open to try to fully feed your indoor coil and it sounds like your head pressure is to low to force enough refrigerant thru the coil.
Has anyone added refrigerant? If there was a blockage I would think the suction pressure would be lower. Are you sure it isn't just overcharged. If you take the ambient and add 20F that would give you a condensing temperature of 105 which gives you a pressure of about 210# on the high side and something to shoot for. I don't know if this helps you. Also, the numbers I listed are for R22. You didn't mention what type is in the unit.
Hi, sounds as though for this to be its 2nd compressor for such a newer unit, the superheat was not right when the compressor was installed. I don't know what freon you are using the new R-410A or the regular R-22. There's a big difference in pressure, but now I see your pressure reading and its R-22 for these readings.For a 2 ton unit, you would use the superheat charging method for a unit that doesn't use a thermostatic expansion valve ( T X V ) and not the sub-cooling. A 23 degree super heat at that outdoor ambient temperature is way to high for that unit, you will loose the compressor again!!. Super heat killed the compressor is the saying and that's a fact. Suction pressure should pull down just as quick as the head pressure unless the valves are going and weak, or you have a scroll compressor that has a valve plate that is going, or you are low on charge. With a ambient of 95*, you should be at around 270p.s.i. on your head pressure as 210 to 200 is way low. Suction line temp should be around 68 to 70, with a suction line temperature of 50 to 51 degrees, which would give you a 10 to 12 degree F super heat. I don't know when the second compressor was installed, but it has to be low on charge to be such a low head, and high super heat and you will loose this compressor again, its only a matter of time before you have a burnout. It was either under charged when installed, or has a very small leak at one of the joints. I hope the liquid line drier was replaced also. It shows me you have some knowledge on a/c operation, so you need to get that superheat down to between 8 and 10 degrees for this unit to cool properly, and leak check it also. Did you buy a extended compressor warranty? Lets get the head pressure up and superheat down and you should be OK unless the valves or valve plate is weak. Once you loose the valves, you will have a lower than normal head pressure and a high suction pressure. Compressor just won't pull down anymore. I hope I have been of help to you and ask of you to be kind when rating me. I will be here for you if and when you need me for anything. Sincerely, Shastalaker7 A/C & Heating Contractor
You have a low refrigerant charge. Your low reading which coresponds to the temp at the coil 49psi is about 20 degrees fr. It should be closer to 70 psi depending on the ambient temp indoors. The coil has to be above freezing I usually shoot for 38 to 40. your sub cooling needs to be at least ten. And if you cant feel the heat leaving throuhg the condenser fan it aint moving it.
you have a missmatched system, for it to work try removing the orfice on the high side txv it is not allowing the evaperator coil to fill with refrigerant properly coleman and intertherm dont like each other since they control a large market in the manufactured housing heating and cooling units electricaly connecting the componets together no issue prefromance sometimes is the issue hope this helps