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I have had a similar problem with one of our heat pumps. Orignally, when switching from heat to cool, or vice versa, the inside unit and fan would come on, but not the outside unit. I had to go outside and press the pressure reset switch at the bottom of the unit. It would then fire up and work fine. A friend had told me about this potential glitch. Once reset, the unit would continue to fire up when required.
This fall, when switched over to heating, the unit failed to fire up. It worked when I pressed the switch, but then failed to fire up again a few days later. It eventually got to the point I had to go outside and press the pressure reset each time. The technician blamed it on a stuck switch and not enough freon in the system. It has worked since his call.
When the system was not working, the inside fan would come on, but no heat. Once the inside temperature dropped a couple of degrees, the internal auxiliary heat unit would kick in. But it is very expensive to run.
Set your unit to start, then press the outside switch to see if that gets it going. If you're lucky, you will only have to do that once each season change over.
Not all systems have a "pressure" switch that you speak of. In fact many don't. I'm not sure I've ever seen one to be truthful. I've worked on Rheem, Goodman, Trane, Carrier, Bryant and BDP. The last three are basically the same. I'm not calling you a liar, I've just never see one.
Not all systems have a "pressure" switch that you speak of. In fact many don't. I'm not sure I've ever seen one to be truthful. I've worked on Rheem, Goodman, Trane, Carrier, Bryant and BDP. The last three are basically the same. I'm not calling you a liar, I've just never see one.
Its a little red rubber covered button near the bottom right of the unit. I have three Rheem scoll units at our house. All of them have it.
Maybe calling it a pressure reset switch is incorrect.
A thermal overload should only reset once the temp. of the motor is down below a certain point. It could be a pressure reset switch.
Upon further investigation it does appear to be a high pressure switch. Not really something I would think you'd need more refrigerant but as long as it's fixed it doesn't really matter. I learn something new everyday.
A thermal overload should only reset once the temp. of the motor is down below a certain point. It could be a pressure reset switch.
Upon further investigation it does appear to be a high pressure switch. Not really something I would think you'd need more refrigerant but as long as it's fixed it doesn't really matter. I learn something new everyday.
The unit was actually serviced three times for the same problem. Two guys said pressure too low. One guy said pressure too high. Home Warranty insurance paid each time. I'll keep calling them in until they finally fix the problem permanently, or replace the unit.
A heat pump does require freon year round, not just in the summer. I don't know the technical details but that's what I've been told by our HVAC people when they come to fix it.
The HVAC system is an enclosed circuit that shouldn't need freon unless it has leaked out from when it was installed/repaired. In the cooling mode the indoor coil is the evaporator and the outdoor coil is the condenser. In heating mode the cycle reverses and the roles of the coils switch. If you've ever noticed in the summer the heat coming off the outdoor unit is warmer than the air going into it. That's basically what happens to the indoor coil in heat mode. The outdoor unit pulls outside air through the outdoor coil and the heat the refrigerant takes in is then compressed - by the compressor- and pumped into the indoor coil as a hot gas. The indoor coil has the air inside the conditioned space circulated over it and that hot gas condenses down to a liquid and returns to the outdoor unit. This cycle is why you feel the temp. coming out of the vents lower as the outdoor temps. lower. It has a direct correlation to the outside temp. Some people say a heat pump is useless below 32°F which is false. The heat pump can extract heat from the outside air at temp. very much lower than just about any location short of the North Pole. The refrigerant boils - at atmospheric pressure - @ -41°F. What that means is that it's almost always going to boil the refrigerant until the outdoor air gets to -41°F or lower.
The main concern is the point at which the heat pump becomes less efficient than the heat strip. This is called COP or coefficient of performance. Resistive heating - like is used in the strip heat, incandescent bulbs, hair dryers, stove tops and ovens - has a COP of 1:1. That means for every watt that is used in that circuit you'll get 3.413 btus. Since a heat pump mechanical moves heat it can do it more efficiently than the resistive heating circuit. In many cases - at 55-60°F - the heat pump has a COP of 3.5-4.0. That means for every watt used to move the heat from outside to inside you'll get - at 55-60°F - 11.95-13.65 btu, depending on the mfg of the unit. As the temp. drops that COP drops. At around 17°F the COP is somewhere around 1.5-2.0 (depending on the mfg again) which means you'll get 5.12-6.83 btu for each watt used to transfer heat from outside to inside.
Basically you want to use your heat pump as long as you possibly can as long as it's keeping your home the temp. you want it. The strip heat should come on only when the unit either goes into defrost - which reverses the cycle and temporarily shuts off the outdoor fan effectively putting your system into cooling mode - or when the there is no enough heat outside to transfer into your home to keep the thermostat satisfied. Just because you have a better efficiency ration using the heat pump, even when it's very cold outside, doesn't mean the total btus are enough to offset your homes heat loss.
I know this is old - But I think what happens with modern units is that the internal unit tries to assist the heat pump - In my case this is tripping the pressure switch - The solution I believe is to reposition the heat exchanger to be in front of the gas burner - That way the secondry heat will assist the heat pump - But ??
... I did notice that the heat pump is running on emergency heat ALL the time, even if the system is set on aux....
You think you have it bad, the ASHP I have doesn't even have emergency heat. When it drops below a certain temperature outside, I shut the system down and use space heaters to heat my Master Bedroom. Next year is going to be fun, since I have a new baby, I'm going have to figure something out to heat her room too.
The downstairs is a different zone, heated by Geothermal Heat Pump.
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