Installing a biomass boiler: what it's really like
Posted by Harvey Jones on 14 March 2012 at 8:01 am
We’re off the mains gas grid so I chose biomass (wood chip) to replace our old oil-fired boiler as I wanted to be as CO2 neutral as possible. It also meant there was no possibility of a catastrophic heating-oil spill. Our old, cold house already had central heating with radiators and we were told by the suppliers (Covers Eco-Centre in Chichester) that air- or ground-source heat pumps would require the installation of underfloor heating which wasn’t practical.
Covers made a site visit and recommended the Windhager BioWIN Exclusiv system. They also recommended a local installer who visited us to check the Covers suggestions. Before finalising the order, Covers made a second site visit with a Windhager technician.
At the end of all this, we’d decided to site the boiler inside an open-fronted car barn and run the water underground into the house. The heating matrix would sit in the place of the old boiler in our boot-room and connect onto our existing heating system. We would also run water to an outbuilding that I was converting into an office and which would have underfloor heating.
Installing all the Windhager kit went very smoothly but I then realised that, despite the numerous site visits, nobody had thought of how to move the water from the boiler into the house and out again to the outbuilding. It turned out that the initial order (and quote) had covered all the Windhager components but nothing else.
In the end, we decided to go for super-insulated underground pipes which added almost £2,000 to the cost of the system. We also had to dig holes through the house foundations and up inside with another through the floor of the car barn and then make good all the damaged floors etc.
Once the plumbing was complete and the mains electricity spurs laid in, Windhager themselves came to commission the system. They were super efficient and got everything running in a morning but I felt they could have spent a bit longer explaining how the system worked.
In order to minimise pellet use, the Windhager computer measures the outside air temperature and sets the water temperature accordingly so the radiators get hotter as the air outside gets colder. The indoor controller units do have temperature sensors as well but this is only used to moderate the circulating water temperature - they don’t function like the old-style on/off thermostats that I was used to.
I spent many a happy hour setting all the dials with a screwdriver before we had a house that wasn’t too hot on mild days and too cold on frosty mornings. I’ve got this all sorted now and we have a warm house for the first time since we moved in (although we do have a fine new Morso log-burning stove as well).
We are now very happy with the boiler but it’s much more of a lifestyle commitment than a gas or oil one. For a start, it’s huge. The boiler itself is twice as tall as our old oil-fired one and has a pellet hopper by the side which is as big again.
Then you have to factor in the pellets themselves. These are supplied in 10kg bags with a ton on a pallet costing just over £200 so each bag is a little over £2. On a really cold day, the boiler is on 24 hours and burns about 7 bags of pellets - it’s only 2 bags on a mild day. This means topping up the hopper anything between 2 and 5 times per week.
Filling the hopper generates a lot of dust which you wouldn’t want indoors and a pile of empty plastic sacks which I have yet to find a use for. In order to have some pellets in stock and take a delivery of new ones, you need room for at least 2 pallets. That’s as much space as a Mini. With 2 tons of pellets and the boiler in it’s protective box, it’s a single garage full of stuff. You also need a pallet truck to move the pellets (and that doesn’t work if they’re on the wrong kind of pallet) and at least two strong people to move them around. Add in lifting the 10kg bags to shoulder height to tip them into the hopper and you can cancel that gym membership.
Putting this little lot inside a house (as was initially suggested to me) is crazy. As it is, the water-distribution matrix looks like part of an aircraft carrier with its temperature gauges and brass taps. There are wires everywhere on it with thermostats and electrically operated valves all controlled by a central brain. It’s all rather lovely in a techno way but it’s not very homely and we’ve boxed ours in behind a false wall with access panels. That part of the system is also really noisy. It ticks and gurgles constantly and you certainly wouldn’t want to be watching TV or sleeping anywhere near it.
Don’t get me wrong, now it’s all installed I love it. We’ve got a warm house and we’re not burning fossil fuel. Delivering the pellets is no worse than delivering the heating oil and they’re made fairly locally in Andover. I like the physical connection to our energy usage although that may become more problematic as I get older.
I do think the system is more suited to light industrial units or groups of houses, though. Then you could have a massive hopper installed to take a year’s worth of pellets which can be delivered in bulk.
If you’re thinking of having one installed into an existing property, make sure that the installers give you a quote for absolutely everything you need and then factor in any extras for digging and refilling trenches, building storage buildings and hiring strong friends. You’re not just getting a heating system, you’re getting a whole new way of life. More like getting a dog, really.
More information about installing biomass from YouGen
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