Heat Pump control problems, Review and Update

[Art Renkes]

The info in this message is offered in the hopes that it might be helpful to someone else with a problem similar to mine. My earlier messages on this topic were posted on 5/21/04 (Heat Pump Performance Questions), and 6/2/04 (More Heat Pump Questions). In summary, the performance at that time had become very erratic and unpredictable (refer to original post), and my daily power usage had climbed to an average of 103 KWH per day for the four days in May when the erratic performance was first noticed. The company that installed the system in 1998 sent (at my request) a service technician who judged the system to be "working normally". It was at this time that I began to monitor my power usage on a daily basis and discovered the abnormally high usage. Suspecting that the T-stat might be responsible for the erratic performance, I decided to at least inspect its' wiring connections. (The system is a Carrier Heat Pump, and the T-stat is also a Carrier unit - digital, but non-programmable.) The T-stat is mounted by a hinge to a base that is attached to the wall, where swinging the T-stat away from the wall disengages several pins from a mating socket and totally disconnects the stat from the system. After going through this procedure one time (disengaging and re-engaging the pins with the mating socket), the system performance abruptly became normal and predictable. At the same time, our power usage dropped from

103 KWH/day average (during the erratic performance period) to less than 40 KWH/day average for the months of June, July, and 1/3 of August (in Central Florida). I may be wrong, but until something better comes along, my theory is that a faulty contact between pin(s) and socket may have resulted in inconsistent actuation of the reversing valve in the system, and that the friction of momentarily breaking and re-making this connection has at least for now resulted in a 'good' contact. It seems to me that this could explain both the warm air we experienced many times while in the cooling mode, and the much higher than normal power usage observed during the erratic performance period. Any different theories and/or comments will be welcomed. Thank you. Replace deadspam with yahoo to reply.

[PrecisionMachinisT]

Sounds reasonable.

Reversing valves can be "plumbed" either to default on heat or cool........I would assume yours defaults to heat--in any case, a helper should be able to hear the valve click at the condensor when it is energized / de energized whenever you manually change the stat setting from "off" into either the "heat" or "cool" mode.

[TURTLE]

This is Turtle.

If this is the case then remoe the thermostat one more time and take a pencil eraser and clean the pins and the plate or attaching plate that the pin hits. The pencil eraser will cut away any crud or dirty that will keep it from making good contact.

TURTLE