Heat Pump Runs Constantly


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Old 12-22-02, 07:41 PM
mrskg
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Heat Pump Runs Constantly

We live in Powhatan, Virginia where the daytime temps. have been averaging in the 40-50 degree range but there will be an occasional day where the temp doesn't get out of the 30s. Night time temps range in the 30-40 degree range and ocassionally the temp drops into the teens. Our house is two-story and framed and was built in 1994. There are two heat pumps and the one we're having trouble with is a Trane, model #TWRO30C100A2, the heater unit model number is TWHO30140A1. The thermostat model (Trane) number is BAYSTAT239. The problem is that the heat pump continues to run even after reaching the temp. set on the thermostat. We've had to shut it off at the circuit because it gets quite warm in the house. Prior to this, we noticed that the unit would turn on for a few seconds and then shut off again. Do you have any idea what might be wrong?
 
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Old 12-22-02, 07:49 PM
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Could you specify whether the indoor and outdoor units run together or is the problem with the indoor unit. I could believe that the outdoor contactor welded together, but that would not make the indoor fan run.
 
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Old 12-22-02, 07:51 PM
mrskg
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The indoor and outdoor units do run together.
 
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Old 12-23-02, 05:16 AM
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It sounds like a thermostat problem to me because of the two units running together. What happens when you switch the thermostat to off during the overrun? If the system stops, you could assume it is a thermostat control problem. Does the unit ever stop? Like if you set it at 60 and see what temperature it finally stops at. Gather all the info you can.
 
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Old 12-23-02, 08:43 AM
mrskg
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When both circuits are on, the unit continues to run regardless of whether the thermostat is shut off, set as low as it will go or both. Right now the circuit marked "furnace" is on, the circuit marked "heat pump" is shut off and the thermostat is on and the aux. heat has kicked on. However, with the same circuit configuration, if the thermostat is shut off, the aux. heat shuts off and cool air comes through the vents.

Whenever we set the thermostat to 65 or above, the unit (when both circuits and the thermostat are on) continues to run. If it's set below 65, the aux. heat will come on if the thermostat is registering a temperature below 65 and once the temperature has reached 65, the aux. heat shuts off but the unit continues to run.

Do you have any idea where we might be able to locate an electrical diagram for the unit? My father-in-law is an electrical engineer and replaced the thermostat in our old house. He's interested in finding a diagram of the unit to check whatever he thinks needs to be checked.

Thank you so much for all your help.
 
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Old 12-23-02, 09:11 AM
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I would bet that you could get more effective troubleshooting help from someone other than me, but if we haven't gotten any other replys yet we can just keep trying the process of elimination. How old is the thermostat? What is your feeling about removing it from the circuit all together and seeing if the unit stops? Then you would have a better clue. Or swap it with your other thermostat if the heat pumps are both Trane. I could not find anything about a BAYSTAT239. I found TAYSTAT??? but no 239 so can't help there. There should be a wiring diagram inside the electrical compartment for both units but you might not want to get inside just to get at them. 240 volts in both.
 
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Old 12-23-02, 11:17 AM
mrskg
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My best guess is that the thermostat was installed at the same time the heat pump was back in 1994 but I don't know that for sure. We're the third owners of the home so there's no way of knowing if the thermostat was ever replaced. It may be a TAYSTAT and not BAYSTAT since my father-in-law was calling out the letter/number combos to me and it's quite possible I heard him wrong. I'll suggest to him that he remove it from the circuit as well as switching the thermostats and see what happens.

You've been a tremendous help and it's much appreciated!
 
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Old 12-23-02, 01:24 PM
bigjohn
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It's BAYSTAT. As for a wiring diagram , there should be one inside the indoor and outdoor units. Also, Trane usually puts a pamphlet inside both the indoor and outdoor section tited "Service Facts" or something similar. They usually contain a wiring diagram. Now I'm a little confused here and I need you to help me sort it out. When the system is running constantly but the aux heat is not on, the house gets too warm? IOW- both the outdoor and indoor sections are running and if you listen to the outdoor unit, you can hear the compressor running? Then when you turn the thermostat to off do both the indoor AND outdoor sections keep running or just the indoor section? [this is with all circuit breakers on] In this mode does the house continue to overheat? The thermostat should have a separate switch for the indoor fan. Are you sure that switch is set to auto?
 
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Old 12-23-02, 01:54 PM
mrskg
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Thank you for letting me know where to locate the wiring diagrams!

I discovered today, that if the thermostat is set at 65 or above, the unit continues to run and the house does indeed get too warm and the compressor and indoor sections continue to run even if the thermostat is shut off. If it's set below 65, the unit will eventually shut itself off but the house is quite cool. As for the thermostat, it's always set on auto.
 
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Old 12-23-02, 05:15 PM
bigjohn
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Based on your description, it has to be a bad thermostat. When you turn the system switch to off, both sections should shut off. I assume that this is a new problem and has not existed since new? Feeling ambitious? Go to http://hbctechlit.honeywell.com When you get there, click accept. On the next page, select description and all literature, and then type heat pump thermostat cross reference into the "search for" block. You'll get a 124 page document that you can download and then look for a replacement part number using the BAYSTAT number or there may be another long number on your thermostat that you might have to use. Most likely your thermostat was made by either Honeywell or White-Rodgers to Tranes' specification. You might try the swap thermostats idea first but only if the other system is a Trane heat pump and the other thermostat has the same number.
 
 

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