The ground source heat pump worked well for about 2 weeks and then started shutting down with a low pressure alarm. This is normally due to an issue with circulation of fluid in the ground loops. Last Friday, we had to give up and turn the unit off altogether. We have now been without heating and hot water for the last week.
Initially, it was thought that it was dirt in the system, but there was no dirt in any of the strainers and the system was flushed to prove the point. Then it was thought that it was the pump that pumps the antifreeze around the ground loops. This was replaced, but the fault still persisted.
Neither the installer or NuHeat have been able to resolve the problem despite their best efforts. This issue now resides with Nibe who are the manufacturer of the ground source heat pump unit itself. Unfortunately, this means further delays as we have to wait for an appointment for the engineer to come out.
When the heat pump is back up and working, it will take 2-3 days at least for the property to get back up to full temperature. We are just gratefully that it hasn’t been too cold yet this winter!
Hi sorry about your situation, but has no oe told you how to switch it over to emergency mode ,by blocking the compressor and just using the electric heater
Regards scott
Hiya,
Yes, I am aware of this. In fact, we used it over the Christmas period to dry out the floors before the heat pump was commissioned. However, I don’t think you would want to use a 6kW immersion heater for too long. Having said that, we used it for about 10 days and the electricity bill wasn’t as bad as I thought it might have been, particularly since we had a dehumidifier running at the same time.
The ground source heat pump is now working thanks to a Nibe engineer last week. I reckon the property should be up to full temperature in the next couple of days. I had been warned that sometimes they take a little while to settle down. Hopefully, we are over the “bumpy” period.
Thanks for the comment.
S.
Hi Steve,
Can I ask you what the actual fix for the heat pump was?
Regards
Richard
Richard,
The problem was that the system was throwing a “low pressure alert”. This normally means that there is a problem with the fluid running in the ground loops – I am told that 9 times out of 10, that it will be air in the ground loops. However, the system was flushed twice without any sign of their being air in the system. At this point both Sol-Air (the installer) and NuHeat (the supplier) drew a blank and had to call in Nibe (the heat pump manufacturer).
The Nibe engineer checked the flow on the ground loops as well as checking all of the relevant pressures (it was a low pressure alert after all). He even took the gas out of the compressor, weighed it, and re-charged the compressor. All checked out fine. However, the engineer did notice that as the compressor on the heat pump kicked in that the pressure dropped. He suspected that the temperature of the water in the buffer tank – this is the other side of the heat exchanger (the side that the ground loops transfer the heat to) – was too low (it was around 10C). So he stopped the compressor and used the immersion heater to bring the temperature of the buffer tank up to about 20C. Then he re-engaged the compressor. We shut off all of the underfloor heating manifolds and opened them one by one – always keeping an eye on the pressure, making sure that it didn’t fall below the cut off.
This all worked. It took the Nibe engineer 5 hours to find and correct it. He said that it was unusual, although they have seen similar problems with air source heat pumps.
Everything is now working. However, we have had a couple of low pressure alerts in the last couple of weeks, so I am hoping that the problem has not re-emerged. We will see.
S.