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Thread: Need to buy or make a Heat Pump Controller

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    Need to buy or make a Heat Pump Controller

    I am seeking information and help, so I am posting this to the most diverse well informed group of people I know.

    I installed a geothermal heat pump system when I build my home back in 1988. Not sure how much preliminary information to put here, so this is a short summary. The system has a closed loop water+ propylene glycol source loop. Originally I had a 6 ton water to water heat pump that I purchased used. It quit working after 20 years. I now have two 3 ton units. The heat pumps take heat from the source loop to keep a 50 gallon tank in the basement between 95-100ºf. (in summer this is reversed and the tank is 38-43ºf) Hot water from the tank is then distributed as needed through the radiant heat system in the floor of the house. Each room has its own heating thermostat and floor loop (In summer the cold water is pumped through air handlers for cooling with one thermostat). The two heat pumps are staged so that only one runs unless there is a very high heating or cooling load, then the other one kicks in. I went with two separate units instead of a dual compressor model so if one unit fails, the other one can still function.

    Here is the problem. The controller on one of the heat pumps is failing. I am not able to find a replacement. The heat pumps I got are were made by Florida Heat Pump. (WW036-1USC-FXX) They are now out of business. Apparently they were taken over or purchased by Bosch. I contacted Bosch and got no response. Each unit has an ICM controller. (LPR-AM7805, 641-190). I contacted ICM to see if they could provide a replacement. Their response is they made those controllers for FHP and have no replacements and nothing similar.

    These heat pumps are not rocket science. They are just a collection of standard components you could get at any good HVAC supply house; Copeland scroll compressor, compressor contactor, reversing valve, heat exchangers, control circuit transformer, a temperature sensor, high and low pressure sensors and the controller.

    What I am seeking now is a solution to this problem, either by some other manufacturer or homemade.

    Any ideas would be appreciated.

    Thanks for your time,

    John

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    Quote Originally Posted by hemmjo View Post
    I am seeking information and help, so I am posting this to the most diverse well informed group of people I know.

    I installed a geothermal heat pump system when I build my home back in 1988. Not sure how much preliminary information to put here, so this is a short summary. The system has a closed loop water+ propylene glycol source loop. Originally I had a 6 ton water to water heat pump that I purchased used. It quit working after 20 years. I now have two 3 ton units. The heat pumps take heat from the source loop to keep a 50 gallon tank in the basement between 95-100ºf. (in summer this is reversed and the tank is 38-43ºf) Hot water from the tank is then distributed as needed through the radiant heat system in the floor of the house. Each room has its own heating thermostat and floor loop (In summer the cold water is pumped through air handlers for cooling with one thermostat). The two heat pumps are staged so that only one runs unless there is a very high heating or cooling load, then the other one kicks in. I went with two separate units instead of a dual compressor model so if one unit fails, the other one can still function.

    Here is the problem. The controller on one of the heat pumps is failing. I am not able to find a replacement. The heat pumps I got are were made by Florida Heat Pump. (WW036-1USC-FXX) They are now out of business. Apparently they were taken over or purchased by Bosch. I contacted Bosch and got no response. Each unit has an ICM controller. (LPR-AM7805, 641-190). I contacted ICM to see if they could provide a replacement. Their response is they made those controllers for FHP and have no replacements and nothing similar.

    These heat pumps are not rocket science. They are just a collection of standard components you could get at any good HVAC supply house; Copeland scroll compressor, compressor contactor, reversing valve, heat exchangers, control circuit transformer, a temperature sensor, high and low pressure sensors and the controller.

    What I am seeking now is a solution to this problem, either by some other manufacturer or homemade.

    Any ideas would be appreciated.

    Thanks for your time,

    John
    The Homemade Heat Pump Manifesto - EcoRenovator
    ecorenovator.org › geothermal-heat-pumps
    This is the most informative heat pump tech I am aware of. It's been 3 years since I read it all and it took me several evenings. I believe he made his own controller but I am not certain. I'm sure there is useful information here. Good luck

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    A quick web search shows that there are two second hand LPR-AM7805, 641-190 on ebay right now. One in Spanish ships from Ohio and the other from Hong Kong. Both are USD60.
    It is unusual for electronics to fail gradually. Sometimes they get intermittent faults then fail completely. Have a good look at the circuit board, look for burning/overheating signs, look for dry joints, loose screws and wires, unplug and re-plug plugs and sockets several times to clean their contacts. Swap over the controllers with each other if this is easy, and see if the fault is transferred to the other unit. Any electronic repair person could probably check and repair components for you if it is a simple board without many components. A good HVAC tech might even be able to replace the controllers with something more modern and reliable.

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    You mat want to look into a PLC controller. A Programmable Logic Controller is able to control inputs and outputs by the use of a program which you set the parameters. Some are as small as a pack of cigarettes. Prices start around a %100 buck. The logic for say a GE PLC is pretty much strait forward once you figure out the logic of what you want it to do. Just an idea.

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    Thanks for the input so far.

    I checked out the heat pump manifesto, very interesting, but no real controller.

    I hesitate to gamble on a those from eBay especially since one seller, located in HongKong is selling an item from Ohio, which is where I am located. The other also in Ohio is in Spanish. Probably 2 sites selling the same item. The skeptic in me sees a scam of some sort so not worth the gamble for a used controller.

    I have compared the two controllers and swapped them between units. The problem is for sure with one controller. The issue is the LEDs that display status, i.e, heat, cool, auto, off, and fault, do not work. I can tell the mode, by watching the temperature set-points change as I switch between modes. So I know when it is in Heat, Cool, Auto or OFF. It is functioning for now but if there is a fault, I would not see that, the unit would just stop running.

    As suggested, I have examined the board for signs of failure, having repaired several digital automobile dash components, a climate control module, 2 different speedometers and a tachometer, by simply reheating all of the solder at the circuit board connections. I just hesitate to mess with this unit since it is working. I do not see any of the typical signs of a failed component on the board. Since all of the LEDs quite working at the same time, it could very well be just a failed solder joint. If it had failed completely I would try resoldering everything. I may the resolder in the spring when I have time to do something else if I ruin it completely.

    I have been wondering about trying a PLC, perhaps using one to control and stage both units. I will have to look into that if nothing else comes to light.

    John

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    Quote Originally Posted by hemmjo View Post
    Thanks for the input so far.

    I checked out the heat pump manifesto, very interesting, but no real controller.

    I hesitate to gamble on a those from eBay especially since one seller, located in HongKong is selling an item from Ohio, which is where I am located. The other also in Ohio is in Spanish. Probably 2 sites selling the same item. The skeptic in me sees a scam of some sort so not worth the gamble for a used controller.

    I have compared the two controllers and swapped them between units. The problem is for sure with one controller. The issue is the LEDs that display status, i.e, heat, cool, auto, off, and fault, do not work. I can tell the mode, by watching the temperature set-points change as I switch between modes. So I know when it is in Heat, Cool, Auto or OFF. It is functioning for now but if there is a fault, I would not see that, the unit would just stop running.

    As suggested, I have examined the board for signs of failure, having repaired several digital automobile dash components, a climate control module, 2 different speedometers and a tachometer, by simply reheating all of the solder at the circuit board connections. I just hesitate to mess with this unit since it is working. I do not see any of the typical signs of a failed component on the board. Since all of the LEDs quite working at the same time, it could very well be just a failed solder joint. If it had failed completely I would try resoldering everything. I may the resolder in the spring when I have time to do something else if I ruin it completely.

    I have been wondering about trying a PLC, perhaps using one to control and stage both units. I will have to look into that if nothing else comes to light.

    John

    As a 40 plus year tech I would say that the most common problems are a bad connection or a relay on the board. I have repaired boards by going over the board with a soldering iron on every connection. Many times you will not see any bad connections but the soldering may fix the problem. As for the relays see if you can check continuity with a meter across the contacts in the open and closed state. If one of the relays is suspect try ordering one on line as they are fairly inexpensive in comparison to a board. Companies that might carry the relays could be Mouser, Newark, Allied etc. If you can find a number on the relay you can search it out. Also do a search for anyone that might have a schematic for the board, that way you might be able to come up with a part number for the components. Good luck

    Craig


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