http://crowncapitalmngt.wordpress.com/ Work started in the warm August of 2009 when we didn’t need heating. Hot water was supplied by an immersion heater as we didn’t have the Solar Thermal panels up at this point (they came in 2010). The estimated install was meant to be two weeks but it took six in total. We allocated one half of a double garage to the project in an area co-located with the existing gas-boiler for convenience. Installation was largely trouble-free. The UK representative of the Manufacturer (KWB) came out for commissioning and observed that one section of pipework was incorrect. It was quickly rectified. We live in a Conservation area and had planning permission refused for an external flue so we had it route through the corner of the bedroom over the garage. Not a big problem as our installer arranged for builders to come in and box in the flue. We redecorated ourselves.

1. Are Biomass Boiler
Costs Justified?

2. Biomass boiler costs don’t end with installation. Mark Brown
takes a frank look at the pros and cons of a biomass boiler for a 5
bed detached house.
Biomass boiler installation
Work started in the warm August of
2009 when we didn’t need heating.
Hot water was supplied by an
immersion heater as we didn’t have
the Solar Thermal panels up at this
point (they came in 2010).
The estimated install was meant to be
two weeks but it took six in total. We
allocated one half of a double garage
to the project in an area co-located
with the existing gas-boiler for
convenience.

3. Biomass boiler system
Installation was largely trouble-free. The UK representative
of the Manufacturer (KWB) came out for commissioning
and observed that one section of pipework was incorrect.
It was quickly rectified.
We live in a Conservation area and had planning permission
refused for an external flue so we had it route through
the corner of the bedroom over the garage. Not a big
problem as our installer arranged for builders to come in
and box in the flue. We redecorated ourselves.
The KWB Easyfire is a 15kW boiler with a 500l buffer tank. The
system provides space and water heating but we also have both
gas backup as well as solar thermal and lounge wood stove.
Our system is using wood pellets fed from a hopper. The hopper
stores enough for at least seven days in the depth of winter but
can last up to two months in a warm summer. It is fully
automated, other than filling it up with pellets or emptying the
ash (once a year!) no work is required. Our KWB is very reliable.

4. Biomass boiler costs
We installed in 2009 on the assumption that
the Renewable Heat Incentive would pay
for the investment. We could have had a
cheaper boiler make but had to opt for
one licenced for use in a smoke-control
zone. Total cost of the boiler, buffer
tank, flue, labour & VAT came to £15,590
minus £1000 from the (then) Low Carbon
Building program grant.
We use bagged wood pellets and need just
under 5 tonnes a year. They cost about
£230/tonne (delivered + VAT) working
out at £1100 pa approx. We take three
tonnes per delivery with about two
deliveries a year. Note that there are
slightly cheaper options but we prefer
UK-sourced pellets.

5. Pros and cons of biomass boilers
We are lucky enough to have a maintenance contract that covers
five years’ work. It works out at about £150 a year this way, but
you could pay up to £500 pa if unwilling to pay up front for a
contract. This contract includes cleaning the flue and boiler.
Pros
•Of all the technologies you install for heating biomass offer the greatest
reduction in carbon footprint per £ spent
•The KWB we used is able to control the existing Gas boiler and use it as
backup
•Biomass boiler installations cause no more disruption than would
maintenance on your regular boiler. No need to rip up your floors or garden
as you might for a ground-source heat pump installation.
•Biomass boilers use very little electricity
•Biomass boilers can use waste wood (turned into pellets)
•Biomass boilers can use locally-sourced biomass helping your local
economy
•Biomass boilers are a resilient technology when used with other local
microgeneration such as photovoltaics
•Biomass is very clean – you cannot see nor smell any smoke – ever!
•The ash from a biomass boiler takes up hardly any space. When necessary
tip it on your garden as fertiliser.

6. Cons
• Biomass boilers are expensive coming in at
anything upward of £9000. You could get quotes
for well over £20,000 so shop around. Even if
replacing oil it is hard to see a payback without
an additional incentive such as the RHI or a
cheap on-site source of fuel such as wood chip.
• A double garage provides ample storage but
moving and stacking bagged wood pellets
requires physical effort
• It was really hard to find a domestic installer (or
was in 2008/09).
• Don’t forget you will need a buffer tank and
storage space for the fuel. We suggest allowing
the sort of space in which a small car would fit.
• Biomass boilers are not really suitable for small
homes on the gas grid. They are more beneficial
if you have a very large building (ie, farm
house, community hall, church, school, etc.) off
mains gas.

7. • Your Biomass boiler deserves to be maintained properly. The UK market is
only very slowly gearing up so you might be limited in choice. Your average
Corgi registered plumber will not touch it.
• Our KWB boiler’s controllers are sophisticated to the point of being too
complicated. Refuelling from bags can be physically demanding. This makes
them unsuitable for social housing, the physically impaired or the elderly.
• Fuel delivery can be inconvenient (as for any solid fuel) so we normally take
the day off work or pay extra for Saturday delivery. Delivery to narrow cul de
sacs are a problem in our experience so we always specify a small 8 tonne
truck – sometimes this message doesn’t get through and we have had to
push pallets from the road on a pallet trolley with the help of the delivery
driver. This is almost impossible for a one tonne pallet, we recommend ¾
tonne pallets or less. A tail lift truck is recommended. We always end up
part-hand-stacking some of the load to reduce its footprint in the garage.
For one fit man this might take 40 minutes to shift 1.5tonnes of bagged
pellets (15kg per bag). The other option is to use a large hopper with the
pellets blown in – but this is only suitable for much larger installations than
we have.
• Having solar thermal can mean the biomass boiler is hardly used through
part of the summer. However it will keep the buffer tank up to operating
temperature which is wasteful (although this can be switched off). Our
system was sized appropriately based upon our SAP rating so this isn’t a
significant problem.

8. Conclusion
Given the information we had in 2009 (and the pending Renewable Heat
Incentive) we think we made a good choice. However the RHI has not
materialised and, as far as we know, might NEVER pay us a penny for this
boiler in its final manifestation.
When deciding upon this form of heating we did compare it to a ground-source
heat pump. We didn’t cost up a comparable GSHP but it would only have been
suitable if we had been prepared to dig up the floor for underfloor heating
plus the garden for the ground loop. A GSHP would need a lot of electricity to
run but we wanted to generate most of our own power so it would have put
that objective out of reach. Hence biomass was the most local & resilient
option.
We have great satisfaction with the boiler and our only regret is the loss of space
in the garage. We would recommend domestic biomass for rural areas with
large buildings off mains gas.
© Mark Brown Aug 2012