Geothermal Radiant Heat Unit Won't Run Troubleshooting

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Huntington, NY
Hey All-- I've got a bunch of Earthlinked DX geothermal units in our house. One of them is a Classic Series that's used for radiant heat in various rooms throughout the house. I love the system, but the company went out of business a couple of years after we did this huge installation--so no more warranty.

The question I have is about the one unit we have for our radiant zone. I'm hoping that even an HVAC/refrigeration person not familiar with Earthlinked might be able to help me figure out what my current problem with the unit not kicking in might be.

A bit of background first. I had just finished flushing the Boiler Buddy water tank that stores the water for the floors. After doing that I turned on the unit and raised a couple of thermostats. I think I heard the compressor kick in, but am not sure it did before I left. When the floors weren't warm in the morning, I went down to see what was up. The unit was not on. There was power in the unit, but it was not operating. I checked all the valves to the tank that I had turned off, and they were all open. However...

... the valve from the hot water tank to the geo unit was closed. I can only guess that happened when my HVAC guy came over to do some work, and I could have asked him if anything should be closed for the winter--and then I forgot about turning it off. Anyway, I don't know why it was off.

So the question is first, could that closed valve from the hot water tank to the geo unit have caused the problem? And if so, any idea where I might look for that issue? I would think some protection unit would have kicked in.

In addition to the unit not turning on (the compressor), I see that there's no power to the circulator that brings the water from the tank to the unit. So I guess whatever turns on the compressor also powers the circulating pump? The power wire for that circulator comes from something called a lock-in relay, where that terminal has no power, of course.

I already tried turning off the circuit breaker to the unit and letting it rest for a while. All indicator lights on components within the unit are reading normal.

Here's the manual for the unit:

Here's a pic of the electrical parts below. Power supply on the left, that brown lock-in relay next to it.

I know it's a longshot asking this, but figured I'd give it a try. Thanks in advance to any brave, smart soul who responds :)


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John Gayewski

In the Trades
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You need a meter to trace what has power and what doesn't. It could be the circulator is ruined and there's a sensor keeping the test of the unit from operating. You really have to just work your way through the power operations to track down what failed.
Hey, wait a minute.

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