Thursday, April 15, 2010

Heatpump : day of fixing! part 1

15 April : As usual, the heat-pump started the day by going into its familiar overdrive and pushing the water temperature far too high. It really does mess up my big experiment having a machine that cannot respond correctly. The weather was cold, with a North wind, the same one bringing the ash from Iceland that closed down the airports of northern Europe. So if I didn't get it fixed, the machine would be on and off all weekend, perhaps more ON than I would like.
   I had a long series of phone calls with David at Ice Energy. David points out to me that most Heatpump owners can leave theirs on (like a fridge) for weeks or months on end - when we tried this, it consumed 65 kWhr in one day, or it spirals temperatures upwards and then shuts down. So we have managed ours not like a Fridge, rather more like an Oven. You only turn it on when you need it. This isn't right.
  Our series of discussions today seem to have fixed it, although my phone bill will be very heavy at the end of the month. Having read out all the parameters to him, it seemed strange that the transfer fluid temperatures in and out seemed wrong, compared with the ever rising water temperature. For some months, we have blamed the REGO controller. We decided to check all the sensors, perhaps it is them sending wrong information to the REGO controller (the light grey box, bottom right in the photo).

   For the last year and more, I have tried the "IT Crowd" method which is turn it off and turn it on again. This hasn't worked for longer than half a day. The machine is too heavy and plumbed in to try the other classic repair method - give it a good shaking, and a few kicks! :)

   So this time, I took the front and the side panels off and checked all the wiring inside - using a method which I used to find very effective for repairing computers in the 90s, pulling out all internal sockets and plugs, ribbon cables and sensors, and re-inserting them, in case there was a poor connection - checking bellwires from sensors, and power lines to pump and compressor etc. Sensors were checked to make sure they were connected.

Eureka!

The moment all the plugs, sockets, cables etc had been pulled out and re-inserted, I restarted the GSHP. Straight off, it began to behave as it should do!
   The water temp was already so high that we didn't test that until some washing had been done in the house - but when it did work on the hot water, the GSHP boosted it to the correct temperature, plus the hysteresis margin, and then turned itself off precisely! Correctly!
   The heating came on less often, got to temperature more quickly, pulled in heat from the Sunboxes, and then moved to hibernation once the job was done.... Amazing!

 Story continues in the next posting

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