Of all renewable heating products, biomass has got the most to consider before you put a boiler in. If you’re thinking about doing this-these are some questions that you need to ask yourself:
1. What kind of wood fuel will I use?
There are 3 types to choose from: logs, wood chip and pellets. Logs are great if you have a ready supply of logs handy. Maybe your best mate is a lumberjack or instead of a gym membership you like to exercise with an axe! If you can get hold of logs for cheap this is perfect. Remember though-logs need to be dried out for 2 years to burn well. Storage therefore is key.
Chips tend to be used for more commercial premises but can be used for domestic. Like logs they are usually used by those who know they can get hold of them cheaply. Maybe you own a wood chipper for some reason. Again with chips you need to give 2 years drying time so you need to think carefully about storage. A small barn or something similar is perfect.
Pellets are the most common domestic fuel. They are great because there are strict perameters on pellet size and water content which must be adhered to by anyone selling them. They can be bought in 10kg bags or they can be truck delivered.
2. How will the wood fuel get to my boiler?
Again, this depends which fuel you use. Logs always have to be manually placed in the boiler chamber. No way around this unfortunately.
Chips can be manually fed but they are almost always fed by an auger into the boiler chamber. This means that once your store is full it will automatically feed into the boiler with no work required.
Pellets can be either manually or automatically fed. If you don’t fancy lugging sacks of 10kg bags around every couple of days then you will need a hopper which can be fed from a delivery truck. Again, the size of these varies from 200kg to 5-tonne hoppers (obviously there is no limit tot he size of a a bespoke one). For cost, it is best to get as big a delivery as possible but this will mean a bigger hopper taking up more space.
Some areas don’t like any smoke producing equipment. Increasingly though planning regs are recognising the environmental benefits of biomass and easing the laws to suit. In city areas planning tends to be stricter but check with your local council.
4. What are the alternatives?
If you’re on the gas grid then this is obviously an option. If not, then the main options are heat pump, LPG, oil or electric boiler. A heat pump is the ideal if your property is modern and well insulated. Electrically run, no emissions, efficiency through the roof. Put in a heat pump!
The problems with fossil fuels (LPG and oil) are well documented-dirty, expensive, held hostage to price hikes, need I go on?
Electric boilers are very expensive to run but are at least clean. If you really want to go down that route, make sure you have solar pv installed so you can at least some of your costs.
5. How can efficiency of the boiler be maximised?
The usual things apply-minimise heat losses in the property-insulation, double glazing etc. To really make the most of the boiler though, have solar thermal, or even better, solar thermal/pv hybrid, installed at the same time. This will really take the pressure off the boiler and in the summer months, when the heating is off or used rarely, you will find you hardly use any fuel at all.