Hello everyone,
to be direct:
We are currently planning the heating system for our new build. It will definitely include an air-source heat pump with an internal heat exchanger.
The question now is whether to install a water-bearing stove (wood stove with water jacket) to support the heating system.
The big advantage: during times when the heat pump operates inefficiently (evenings in the cold season), the stove can provide support. Other support systems tend to operate effectively only when they are not directly needed (photovoltaics → sunny and usually warmer, solar water heating → summer / sunny winter days).
Our advantage is that we own our own woodland.
What surprises me is that most of the threads I have found so far (here and elsewhere) have a rather negative view of the system (many are also somewhat outdated).
This seems to be based on several points:
* the hot water storage tank must be larger → the heat pump heats a lot of “unnecessary” water
* does not work as expected
* higher investment costs do not pay off
* and a notable comment saying “it’s simply a bad combination”
However, with my theoretical layperson knowledge, I think:
There are water storage tanks of (just to throw a number out there) 500 liters (130 gallons), where the stove feeds water at the bottom and heats the full 500 liters, while the heat pump only heats the top 150 liters (40 gallons). Therefore, theoretically, the extra effort for the heat pump should not exist.
The point about “does not work” can only be explained by control technology in my case—meaning somewhere a small error was made during installation (for example, even when the stove heats the storage, the heat pump is still running simultaneously).
The higher investment costs can be easily calculated. My estimate would be: +2,500 euros for additional installation (pumps, larger tank, piping, installation, etc.) and 1,500 euros more for the stove. This is just an estimate.
And I absolutely cannot understand the point about the “bad combination.” The heat pump gets relieved during its least efficient operating times.
What I’m also thinking: I’m unsure whether a normal stove with 3-4 kW (10,000-13,600 BTU), if placed in the living room, might be too large and cause overheating. It would therefore be good to divert any “excess” heat into the heating system. Unless, of course, you leave doors open and the stove heats the whole house, assuming that works thermally (the stove is located behind a small 90-degree corner).
Has anyone here already had experience with this system? I’m a bit stuck because I personally think it’s a good solution, but the many negative threads have made me hesitate about whether it’s worthwhile.
Best regards
to be direct:
We are currently planning the heating system for our new build. It will definitely include an air-source heat pump with an internal heat exchanger.
The question now is whether to install a water-bearing stove (wood stove with water jacket) to support the heating system.
The big advantage: during times when the heat pump operates inefficiently (evenings in the cold season), the stove can provide support. Other support systems tend to operate effectively only when they are not directly needed (photovoltaics → sunny and usually warmer, solar water heating → summer / sunny winter days).
Our advantage is that we own our own woodland.
What surprises me is that most of the threads I have found so far (here and elsewhere) have a rather negative view of the system (many are also somewhat outdated).
This seems to be based on several points:
* the hot water storage tank must be larger → the heat pump heats a lot of “unnecessary” water
* does not work as expected
* higher investment costs do not pay off
* and a notable comment saying “it’s simply a bad combination”
However, with my theoretical layperson knowledge, I think:
There are water storage tanks of (just to throw a number out there) 500 liters (130 gallons), where the stove feeds water at the bottom and heats the full 500 liters, while the heat pump only heats the top 150 liters (40 gallons). Therefore, theoretically, the extra effort for the heat pump should not exist.
The point about “does not work” can only be explained by control technology in my case—meaning somewhere a small error was made during installation (for example, even when the stove heats the storage, the heat pump is still running simultaneously).
The higher investment costs can be easily calculated. My estimate would be: +2,500 euros for additional installation (pumps, larger tank, piping, installation, etc.) and 1,500 euros more for the stove. This is just an estimate.
And I absolutely cannot understand the point about the “bad combination.” The heat pump gets relieved during its least efficient operating times.
What I’m also thinking: I’m unsure whether a normal stove with 3-4 kW (10,000-13,600 BTU), if placed in the living room, might be too large and cause overheating. It would therefore be good to divert any “excess” heat into the heating system. Unless, of course, you leave doors open and the stove heats the whole house, assuming that works thermally (the stove is located behind a small 90-degree corner).
Has anyone here already had experience with this system? I’m a bit stuck because I personally think it’s a good solution, but the many negative threads have made me hesitate about whether it’s worthwhile.
Best regards
A wood gasification boiler is usually installed in the heating cellar or boiler room. If this space is not in the basement, I would recommend installing an exterior door to bring the wood directly inside.
Now, considering the fact that only 5 cubic meters (approximately 176 cubic feet) of wood pellets are needed to heat an entire house, it really becomes clear why a wood stove in the living area tends to overheat the room. It simply does not require much wood to keep the house warm.
Also, the question remains whether burning 2 cubic meters (about 71 cubic feet) of wood in a stove versus 7 cubic meters (around 247 cubic feet) with a wood gasifier really makes that much of a difference. You avoid dirt in the living area and save on a heat pump plus a wood stove.
The only downside: you cannot watch the fire. Otherwise, in my opinion, there are only advantages—especially if you already have the wood.
If you want to save money by using a wood stove with a water jacket inside the living space, it will take many years to recoup the investment costs. Economically speaking, the wood gasifier is definitely a better option, as far as I can see.
Best regards
Specki
Now, considering the fact that only 5 cubic meters (approximately 176 cubic feet) of wood pellets are needed to heat an entire house, it really becomes clear why a wood stove in the living area tends to overheat the room. It simply does not require much wood to keep the house warm.
Also, the question remains whether burning 2 cubic meters (about 71 cubic feet) of wood in a stove versus 7 cubic meters (around 247 cubic feet) with a wood gasifier really makes that much of a difference. You avoid dirt in the living area and save on a heat pump plus a wood stove.
The only downside: you cannot watch the fire. Otherwise, in my opinion, there are only advantages—especially if you already have the wood.
If you want to save money by using a wood stove with a water jacket inside the living space, it will take many years to recoup the investment costs. Economically speaking, the wood gasifier is definitely a better option, as far as I can see.
Best regards
Specki