On August 19, 2020, the heating engineer comes for regular maintenance on the central heating boiler. Nice to do that in the summer, so we will be well prepared for the heating season. While he is busy I continue my work at hime. After a short time the engineer calls me: the burner is a total loss: after 16 years he says he no longer wants to connect the boiler because it has become dangerous.
After researching various options, I came into contact with HeatTransformers, a company in Woerden that specializes in the installation of heat pump systems, via the "woonwijzerwinkel" in Rotterdam. After our conversation, they recommend a Daikin/Intergas hybrid heat pump, and they install it two weeks later (any idea how long that takes if you have to take a cold shower?).
How does a house from 1955 get to the point where we think we can heat it with a heat pump (ok, hybrid)? When we moved into the house in the winter of 1999-2000, we used about 3000 m3 of gas that first year. Since then we have had the walls insulated, placed insulation blankets in the attic floor, placed beads on the ground under the house and installed HR++ glass everywhere. We have also had the radiators replaced by larger ones in various places in the house during renovations. After all these measures, the weather-dependent control of the water temperature rarely exceeded 45 degrees, and gas consumption fell sharply.
After the installation of the new heat pump heating we immediately made a few changes: fitted the large radiators in the living room with automatic radiator fans, and set the night temperature of the room thermostat much closer to normal room temperature so that the house did not have to be heated up again and again. When the weather got colder, we also noticed that not all radiators warmed up equally quickly: especially the radiator in the kitchen wanted to warm up rather quickly, and when the hot water came back to the boiler, it quickly switched off again without properly heating the living room. We then asked HeatTransformers to tune the system on the water side. They have done this by installing dynamic valves in all radiators that are set to allow just enough water through for each type of radiator. This helped tremendously.
On installation, HeatTransformers had told us that we could probably get 40-50% of our heating from the heat pump. The actual result was much better than that: not half, but as much as five-sixths of the heating capacity in the first year was supplied by the heat pump, with a SCOP of 3.13. In the last year of our HR107 boiler we used 1700 m3 of gas in total. In the first year with the hybrid system it was only 450 m3, of which 200 m3 was for hot water, and of the 250 m3 we used for heating the house, 70 m3 was used in 1 very cold week in February with temperatures of -10 C. In general, the system only starts to burn gas when the outside temperature drops below the freezing point. The 1250 m3 of gas that we now save have been replaced by 4000 kWh of electricity, of which we can collect approximately 1100 kWh with overcapacity of the existing solar panels.