ᐅ Proper Adjustment of the Heat Pump in Combination with a Wood Stove

Hello everyone,

I have a question regarding an efficient control system for my heat pump. Here is my situation:
We have a newly built house with only underfloor heating and a heat pump from Ait (LWD 70A), plus a 10 kW water-driven wood stove and a 1000L (264 US gallons) buffer tank.

Both systems work perfectly fine. However, I want to optimize the settings between the two systems. The goal is to use the wood stove as much as possible for heating and domestic hot water and use the heat pump as little as possible.

The control is quite simple to begin with. If the buffer reaches a domestic hot water temperature of 51°C (124°F), the heat pump does not start. For the heating circuit, it is not that straightforward since it depends on the outside temperature (at least that’s my understanding). Usually, I light the stove around 4 p.m. and it burns until about 10:30 p.m.

When the outdoor temperature was still mild a few days ago, that was enough to keep things comfortable until the same time the next day. But over the last weeks, the situation changed, and the heat pump runs way too often. Of course, I could light the stove earlier, but I’m at work during the day.

Regarding domestic hot water, I was able to manage it quite easily by setting time schedules. I mostly block domestic hot water heating and only allow a short time window when the heat pump is allowed to heat if needed, and it follows that rule well.

But with the heating circuit, it doesn’t work that way. I can change time schedules for both the heating circuit and mixing circuit 1.
How should I set it up for the heating system to make sense? As far as I understand, the heating schedules are not blocking times.

If I forgot any important information or if it is unclear, please let me know. I’m basically just a layperson.

It usually takes the stove half an hour to reach 65°C (149°F) in the combustion chamber before the pump starts. Then it takes quite a while (2–3 hours) for the temperature to build up in the heating circuit and buffer. Domestic hot water is always heated first. I don’t want the heat pump to start during this time. I basically want to set a small time window, like from 11 a.m. to 1 p.m., when the heat pump may run if necessary, but not outside this period.

I know there is the option to disable the heat pump via the utility company (EVU) contact as soon as I turn on the wood stove control. However, I would have to run a cable to the basement for that, and I would prefer not to do that right now. I think this should be possible to control directly via the heat pump’s control unit.

Thanks in advance and best regards