I’m quite interested in getting a wood burner with a boiler (or wetback if you’re from NZ – which isn’t a racist term, but rather refers to the water running through a unit in the back of your wood burner).
I’ve looked at wood burners for a while, my observation is that those available in Australia and NZ are really not as good as those available in Europe. The typical burner down this end of the world is relatively inefficient, puts out a fair amount of particulate smoke (which are very bad for health).
In Europe, there are more interesting units. I have a lot of interest in this unit from Germany, which is relatively small in footprint, and pushes about 1.2kw into the room, 14.4kw into the water. You combine these with a water accumulator such as this unit, which stores hot water for a couple of days after the burner goes out. In theory you could run your domestic hot water and underfloor heating off a combination of these units plus a solar hot water unit – probably evacuated tubes – more about that in a later post.
Having said that, this thread is also interesting, indicating that Australian eucalyptus timber gives issues with resin buildup in a unit not built for it. It also suggests some NZ made units that could be interesting. These are more pure boilers than combined fireplace/boiler. Remember that my better half likes the look and feel of a fireplace in the house, so probably I need something that is a combined wood burner and boiler.
Another interesting point about the German units is that they are sealed – they don’t pull in air from the house, they take outside air into the combustion box, and then vent out the flue. This should reduce dust being dragged into your house, and also if you’re building a house that is very airtight for insulation reasons, avoid issues with lack of airflow and/or with dragging in cold air from outside.
If I ignore that fact that the better half wants a wood burner, I’m more than half tempted to just go with a heat pump instead, much lower maintenance, no cutting and carting of firewood, no ash to clean. But it’s not quite as heart warming in winter as a fire in the corner of the room.