Heat pump problem?

Problems related to residential installations.

Heat pump problem?

Postby RWestman » Mon Dec 12, 2011 4:24 pm

I am somewhat new to using a heat pump. Here is my basic -

1. I live just south of Omaha, Nebraska.
2. I have a Heat Pump that does heat the house.
3. There "IS" an outside temperature cut-off switch (I am told to disconnect the outside unit when the outside temperature is below the pre-set temperature of the switch).
4. I have the switch set to 25 degrees.
5. I have tried the switch at upper limit, 25 degrees, and it still does not shut off the outside unit.
6. The outside unit continues to operate even when the temperature is in the single digits outside.

-

1. How can I test the cut-off switch to make sure it is working?
2. I am guessing somewhere around 30 degrees is the idea cut-off setting. Is that correct/
3. How often should the system go into defrost mode? I believe I heard the HVAC tech say he set it to 15 minutes. It seems, unless we get a LOT of snow or ice or it ices up, that something like an hour would be better and cheaper. If I send a picture of the circuit board area can someone confirm the setting and tell me how to change it?

Thanks ahead of time,

Ron
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- Heat pump problem?

Postby heatseeker » Mon Dec 12, 2011 4:38 pm

The switch is not working if you flip it and it does not turn off the unit, or it could be bypassed. Is the unit turning off when you turn the t-stat off?
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- Heat pump problem?

Postby RWestman » Mon Dec 12, 2011 5:12 pm

First, thank you for the reply. I love forums like this. They are such a great help to people like me.

When I turn the thermostat to OFF or to a lower temperature the outside unit does turn off and the inside unit stays on just long enough to clear out the the hot elements (normal activity).

The box holding the outside temperature switch has the switch and what looks like a relay.

Can I set jumpers to see if the switch is working or not? I do have a VOM, so if you need any measurements I can get those for you.

Ron
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- Heat pump problem?

Postby heatseeker » Tue Dec 13, 2011 9:57 am

Just see if your ohms or voltage cuts out when you check the switch, It is probably faulty.
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- Heat pump problem?

Postby RWestman » Tue Dec 13, 2011 4:36 pm

If the switch is faulty is there a good source online where I can purchase a replacement?

What should I look for to make sure I get a good one?

Thank you,

Ron
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- Heat pump problem?

Postby 4ftBanger » Tue Dec 13, 2011 8:56 pm

I agree that if you turn the outdoor thermostat setpoint to a setting above the outdoor temperature and it doesn't switch the unit off then it is either faulty or miswired - check for continuity through the C-NC terminals on the control while turning the setpoint dial up and down - you should hear a click and the circuit should read alternately open and closed. If the control is working like that then it must be a wiring problem.

The outdoor thermostat is really just a simple switch. Quality shouldn't vary much between brand names as there are really only a couple of manufacturers for parts like that, even though you will find several brand names. ( Sort of like how almost all of the hardware store branded water heaters are manufactured by Bradford White) - It would be pretty irresponsible for any of us to recommend a particular online or brick & mortar parts supplier.

Regarding the other -
How often should the system go into defrost mode? I believe I heard the HVAC tech say he set it to 15 minutes. It seems, unless we get a LOT of snow or ice or it ices up, that something like an hour would be better and cheaper.

The setting on the board is for how often the logic CHECKS for frost conditions. There is a temperature sensor (defrost thermostat) attached to the outdoor coil The defrost cycle should only be initiated if the defrost thermostat senses a coil temperature below freezing. If defrost isn't necessary it just resets the timer and checks again when the set time elapses again.
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- Heat pump problem?

Postby RWestman » Tue Dec 13, 2011 10:34 pm

Lots of good information. So it sounds like I should leave the setting for the defrost where it is.

Can you give me the name of the part I should be searching for if I replace the temperature switch? I have tried Heat Pump Temperature Cutoff and nothing really comes up.

Can you provide a couple of places that do sell the part online and I will choose which one I want to buy from. That way you aren't suggesting a source, just providing a link for me. Or you can email me directly - Teched68048@Windsteam.Net

Thanks ahead of time,

Ron
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- Heat pump problem?

Postby heatseeker » Wed Dec 14, 2011 9:43 am

There are all kinds of parts places to buy stuff online. If you do not know what the part is called you might have difficulty.
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- Heat pump problem?

Postby RWestman » Wed Dec 14, 2011 8:19 pm

Can someone please tell me what to search for to find a Temperature Cut-off Switch for the outside unit?
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- Heat pump problem?

Postby heatseeker » Thu Dec 15, 2011 10:14 am

Did you perform the test to ensure you have a faulty cut out switch?
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