Wood Fire Heating
Wood or log burners work by burning wood to create heat. This heat is directly radiated most of the time into the living room. Radiant heat heats up bodies and not the air, being more efficient than an air heater. Typical radiant heaters create about 60% radiant and 40% air heat. Options of a wood fire include to further heat a water tank for hot water, but it is important to note here that the amount of heat for space heating will be smaller as much of the heat goes into the water tank.
Options to distribute the heat of the log burner around the house:
Using heat transfer pipes that run from above the fireplace to a different room, transferring thereby the heat from one room to another.
Using the heat of the wood burner heats up a water tank. The water of the water tank is then pumped into different rooms where either convection, radiate, or under floor heaters distribute the heat into the other rooms.
You might be able to secure funding towards your heating system in New Zealand. Check the below link for free to access your eligibility.
Fuels for wood burners:
Log burners use most of the time 30cm logs
Pellet fires use small wood pellets, which are often made out of pressed waste wood, utilising a product that was otherwise destined for rubbish.
Efficiency of wood fires:
Wood burners efficiency equals to the amount of heat they get into your room compared to the energy put in through logs or pellets. It varies greatly depending on the burner.
One important factor is how well or clean does the wood or pellet fire burn its fuel. The less ash that is created in a fire the cleaner and hotter it burns, creating less waste. Another important part is the amount of generated heat that is transferred into the room, compared to let out of the chimney. Lastly, for clean and efficient burning of the wood, the wood needs to be dry.
So what are the pros and cons of using a wood or pellet fire?
Advantages of wood/ pellet fires
The fuel comes from a renewable and sustainable resource
The fuel for your heating system is most of the time locally grown
The fuel prices of wood are fairly stable and often cheaper than for example gas
Wood fires help to dry out your home
The sight of a wood fire is a feature in itself, creating a special atmosphere
Disadvantages of wood/ pellet fires
To maintain a higher fuel efficiency maintenance in regard to chimney and fire place cleaning is required regularly
More work is required in keeping the fire place going
Wood fires require storage space for logs or pellets
Masonry wood fires
A masonry wood or pellet burner makes use of the radiant heat of the wood fire as well as utilising the potentially large amount of heat otherwise lost in the chimney. The original german Kachelofen or in english masonry burner is widely used in countries like Germany or Austria.
A masonry wood burner is a wood burner that is put within a special clay tile chimney. The wood burner often has a higher surface temperature compared to other fire places. The clay tile chimney is build up like an obstacle course for the smoke of the wood fire. By acting like an obstacle course, taking different directions, more heat is transferred from the smoke to the tile and given back in the room. Every kachelofen/ masonry fire is unique to each space. It can be formed into heated seats or be put in as a wall in between rooms to heat up both rooms. Options are plenty.
The tiles that are heated will also store part of the heat, releasing it slowly over a longer time period, in some cases up to 8 hours after the fire has stopped burning.