I have a vertical closed non pressure system w 2 command aire heat pumps. They are controlled by 2 Ranco temp controllers. When heat is called Heatpump one kicks on, and after timer delay, heat pump 2 kicks on but will only run for about 30 seconds. And turns off. I was worried thinking compressor was bad but....I unhooke safety switch wire on HP1. (Running Heat pump) Called for heat, heard contractors click but compressor didn’t start because switch unplugged, after timer delay HP 2 fired up and ran perfectly heating buffer tank as it should. This tells me unit is fine. Question why won’t both run together like it’s designed to. System is 12-13 years old. Once winter kicks into full gear, one pump can’t keep up and ancillary heat will destroy electric bill. I’m thinking temp controller but any suggestions appreciated.
What is your closed loop flow rate through each pump ? Maybe there is not enough flow for the two heat pumps to run simultaneously? Thus the second pump locks out with low flow error after running 30 seconds.
Don’t know actual rate but each loop has 2 stacked up 26-99 pumps. Being that it runs by itself and each loop has their own pumps I assumed flow rate would be fine but not sure. I can check the pumps.
He might have meant to say each heat pump has it's own pumps. Can you switch which controller controls which heat pump? To see if it's the #2 controller.
What are the specifications on the ground loop ? Pipe size and length ? You have nine boreholes - correct ?
