Ground source heat pump

2 years after installing the underfloor heating we finally managed to go full-electric by installing a ground source heat pump.

In general there's 2 flavors of heat pumps, air source heat pumps and ground source heat pumps. The first one has a unit outside your house that passes air through a heat exchanger. This is pretty efficient at moderate temperatures, but less so when it turns colder (-10° Celsius and below). You also have to ensure that the outside unit is silent in order to stay friendly with your neighbours.

The ground source heat pump has one or multiple loops in the ground that act as a heat exchanger. If you have a lot of space you can use horizontal loops in trenches more than 1 meter deep. The top 1 meter can freeze, hence it has to be deeper. Or you can go vertical, which we did. We needed 2 70 meter deep loops to have enough length to be able to take the required amount of heat out of the ground without freezing the ground in a couple of years.

Drilling

For these vertical loops you need a drilling machine. A big one. They came in early in the morning and took the full day to drill both 70 meter deep wells.

Loops

Once the wells where drilled the next company came in the day after to put the loops into the ground and fill them with brine, which is an anti-freeze fluid.

Heat pump

The remainder of the week was needed to install the heat pump in our home. We needed new pipes towards all distributors. For cooling in the summer you need pipes of 4 cm in diameter, which the previous installer didn't use.

We have an Alpha Innotec SWCV 92k3 heat pump installed. It's a very efficient machine. However the software is pretty backwards. When looking at the option to shift demand, needed to decarbonize our electricity grid, this machine has no option whatsoever to do such a thing. Looking at brands like Nibe, they already support controlling the heat pumps remotely through an API so it can be used for demand shifting. I'll write a separate topic about demand shifting.

Result

The results are really great. The heat pump is a much better source of keeping your underfloor heating at the right temperature all day long instead of starting and stopping all the time. We used to use 1800-1900 m3 of gas, which is equivalent of 18000 to 20000 kWh. With the heat pump we only use 4000 to 4500 kWh of electricity, making it indeed 4 times more efficient than a gas heating system.