ᐅ Ice formation on brine line of heat pump

We have been using our Viessmann heat pump for a few weeks now. So far, it only needed to provide cooling and hot water, but now that the nights and days are getting colder, we noticed that the ground loop pipe has developed a thick layer of ice, especially in areas where there is little or no insulation on the pipe. During the day, the ice melts and drips, making the floor wet.

I thought this was due to insufficient insulation, and that fully and properly insulating the pipes should solve the problem. However, I recently read that while insulation may help prevent icing, it doesn’t address the root cause, and that this kind of ice buildup isn’t normal. Does anyone have experience with this?

Yes, it is because moisture from the air condenses on the pipes (although there may be other causes as well). Insulate everything thoroughly, and this should no longer occur.

The insulation, where it exists, doesn’t look professional. The pipe clamps are also not installed correctly. They should be insulated cold clamps, after all, that’s their purpose. Generally, you shouldn’t see any exposed pipe at all; otherwise, you’ll sooner or later encounter the problems you described.

Regardless, it’s questionable why brine temperatures are already dropping below freezing. This should actually only happen, if at all, during the coldest part of winter. Normally, there should be nothing more than condensation; ice is unusual, especially in such amounts.

What kind of brine source are you using? What are the current temperatures while it’s running, and at the end of the cycle?

Best regards, Jan

What you wrote, I have also read, that it actually shouldn’t be that extreme with the ice. We haven’t had much so far.

What do you mean by which brine source we are using? We have 3 deep boreholes at 70m (230 feet) each.

In the heat pump’s error log, there is also a note indicating that the primary circuit has a too low supply temperature. I think this is related to the ice and the poor insulation, or is the ice a cause of this?

I can report on our brine heat pump, which has NEVER had such cold circuits. We haven't even seen any condensate. I find that really strange.

Hi, in my previous professional experience, I also worked with heat pumps. Get the service technician as soon as possible, since it should still be under warranty, right?
The reason the primary circuit has a too low supply temperature is because more heat is being drawn from the heat emission side than is available from the heat source side. There can be many causes: air in the brine circuits, brine circuit pump too small or air in it or faulty, one or two brine circuits not circulating properly, pressure in the brine circuit too low, expansion vessel in the brine circuit too small or faulty, or incorrect pre-charge pressure, etc. You as a layperson won’t be able to identify or fix these issues. But as I said, with a brand new system covered by warranty/guarantee, this shouldn’t be a problem. Just make sure to do it quickly before the "real" heating season starts, otherwise you’ll end up with a top-notch electric heater via the electric heating element (which is either in the heat pump or in the storage/tank) and you’ll be figuratively paying your utility company a fortune over the turn of the year.