Swapping oil for biomass to heat a Victorian Orkney house

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Biomass boiler and pellet storeOur house has a fairly unique location situated on the pier in Stromness, Orkney.  Exposure is an issue given it’s surrounded by sea on two sides. The building is a listed, three storey, detached, Victorian, stone house located in a Conservation Area.  The house has 4 bedrooms and many rooms have three outside walls.  There is a large wooden boatshed built onto the east gable.  Recent improvements include loft insulation and double glazing on the first two floors.  Until recently an oil-fired Rayburn provided cooking, heating and hot water.  We also have a coal fire most evenings and electric heating on the third floor of the house.

Although the Rayburn was only installed in 1996 it has proved unreliable and was recently given an approximate efficiency rating of 30-35% (compared with over 90% for modern biomass boilers and gas condensing boilers).  Maintenance costs were high and we were using 4,000 litres each year of increasingly expensive oil.  The house rarely reached a comfortable temperature!

We started to consider alternative forms of heating two years ago but, at that time, we didn’t find it easy to review our options.  We did not have a great deal of confidence in the new technology, the choices were confusing and waiting for tradespeople to assess the best option was a lengthy process.  In the end the only two options that seemed viable were a biomass boiler based on wood pellets or a newer condensing oil boiler.  We were keen to utilise a renewable source of energy but we had reservations about handling, storing and supplying the pellets.

In the summer of 2010 we heard about a generous government grant available to over 75 year olds to install condensing oil boilers.  We talked to the Energy Saving Trust who suggested we should be eligible.  Estimates still had to be obtained from Scottish Gas but we were given a predicted installation date of March 2011.  Fortunately the process was delayed as by early 2011 we were having increasing doubts in being reliant on oil.  Prices for a tank of oil (1,000 litres) had increased to £740 resulting in an annual oil bill in excess of £3,000.  We also became aware of a new scheme called the Renewable Heat Incentive (RHI) to encourage people to move over to biomass boilers.  We also found out more about bulk hoppers which could alleviate our concerns about loading the pellets.

Pellet store of bagsAt this time we read an article in the local paper about a group of renewable energy students setting up a renewables business.  As part of this, were offering free feasibility studies.  They responded to our request for advice immediately, did heat calculations, and supplied information on different boiler options, amount of space needed (including for storage of pellets), potential costs etc.  They also arranged for us to see a biomass boiler in operation.  This could all be passed on to potential suppliers who were registered under the Microgeneration Certification Scheme (MCS).

We requested quotations from a local supplier and also from Green Flame Technology, a company based in Kincraig, Invernessshire.  Green Flame had been highly recommended by one of their customers in Orkney. We only received a response from Green Flame but their quote was favourable and we were re-assured by the fact they were training a local plumber, Davy Prentice of PW Plumbing, to do installations and servicing.

Flue for boilerQuite a lot of preparation work was required before the biomass boiler could be installed.    We checked whether there are local pellet suppliers – there are now two in Orkney.  We arranged for the Rayburn to be removed together while the oil tank was taken for scrap.  A raised platform was built within the boatshed to site the boiler and pellet store to make sure both were kept as dry as possible.  The existing chimney flue was adjacent to this platform and we opened this up from the ‘boatshed side’ to vent the boiler.  [Nb. It is important to have a vertical flue to vent a biomass boiler or stove and also sufficient air ventilation for the boiler itself.]   

Richard da Silva from Green Flame reminded us that we should apply for the Renewable Heat Premium Payment scheme before work commenced.  This was a straight-forward online procedure and, as a result, we received a voucher for £950.  We were also eligible for a grant of £400 from the Scottish government under the Boiler Scrappage Scheme (only operating now in Scotland) – the Energy Saving Trust helped us to get this and emphasized that the application should be made and approved before the old boiler was removed.  We also ordered 1 ton of pellets through our local supplier from Arbuthnott Wood Pellets at a cost of £250 + 5% VAT.  They arrived in 15 Kg bags.  The boiler delivery was organised by Green Flame and arrived from Italy 2 days before the installation was due.

Richard da Silva and Philip McMahon of Green Flame, together with Davy Prentice, took a day and a half to do the installation – their professionalism was impressive and gave us a real boost of confidence that we had chosen the right company. 

Boiler controlsIt is now day 10 since the installation and the boiler is running smoothly and quietly.  Davy the plumber has called in and assisted us with the first cleaning of the ash which is a regular fortnightly process but quite straight-forward.  We have still to learn the intricacies of programming it but we’ll get there. 

We have already noticed a significant difference in the overall temperature of the house and haven’t yet had a coal fire which is unusual for us at this time of year.  During the first week we used 100 Kg of pellets which heated both the house and our hot water.  It is anticipated we will use around 6 tons of pellets a year (£1560).  If you factor in the running costs of our new electric cooker that’s still likely to be a saving of around £1200 annually compared with the Rayburn.  And we’re hopeful we might also qualify for the RHI when it is announced in October 2012 – this could further reduce the payback period to around 2 years.

To sum things up so far, the advantages of a biomass heating solution from our perspective are: they are economical, efficient, quiet, smell-free, and they utilise a renewable fuel source that frees you from a dependency on increasingly expensive oil.  The disadvantages are that installing them can be more labour intensive, filling and cleaning are regular (albeit perfectly manageable) chores, and they take up more space, especially for storage of the pellets.

Biomass boiler in situCost breakdown

Here are our costs broken down:

MCZ 24 kW compact utility boiler:  £3,650

Delivery charge:  £250

Commissioning service:  £260

Plumbing work:  £1,309

Renewable Heat Premium Payment: (£950)

Boiler Scrappage Scheme Payment:  (£400)

Total cost:  £4,319

There were other costs for the removal of the Rayburn and drainage of oil tank but this was more than covered by the sale of the surplus oil.  The cost of removal of the oil tank was covered by its scrappage value.  Two extra radiators had to be purchased for the kitchen and we bought a new electric cooker.

Boiler timer clock on wall

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