With a small patch of woodland containing mainly young ash trees, a patch of willow around the pond and plenty of hedges I’ve long been interested in the potential for burning ‘home-grown’ biomass, from chips, through twigs to logs. So I thought a review of the domestic biomass boiler options was in order…

There are two types of biomass boilers – those fed with pellets and those fed with timber. Pellet boilers can be manually or hopper fed, with hopper feeding allowing a certain amount of unattended operation. Couple hoppers with high degrees of efficiency and the workload for the owner in keeping the boiler running is minimised. For example, Treco claim that the Guntamatic Biostar W boilers will “hold enough fuel for up to a month ….[and are] self cleaning and have ash boxes that only need emptying every 6 – 8 weeks”.

Pellets are small lengths of compressed sawdust, there is no need for any additive to bond the sawdust together as lignin, an organic binding substance present in the wood does this when the pellet is formed under compression.

There are a wide array of boilers available, I’ll concentrate on two of the main ranges available in the UK at the moment…

Baxi offer a number of biomass boilers. They offer two pellet boilers – the Bioflo is manually fed (there’s no hopper so you need to feed it like a traditional boiler) and it can modulate output depending on demand between 3.8kW and 12kW. Then there’s the larger Multiheat boiler – available in 15kW, 25kW and 43kW versions with an integrated hopper. There’s also the Solo Innova, a log fuelled boiler that comes in 20kW, 32kW and 48kW thermal output versions.

Treco supply a wide range of boilers, including those from the Austrian manufacturer Guntamatic. For domestic purposes I’ll consider the Biostar that is available in four different fuel supply options; the Flex (the fuel store can be physically distant from the boiler with the two connected by a flexible vacuum tube), the Box (similar to the Flex, but with the fuel store included in the price), the W (with a large hopper that only needs filling Weekly), and the Biostar Duo (which also burns logs). There are 12kW, 15kW and 25kW versions.

So how much do they cost?
A web search for the Baxi boilers gives me a lowest price of just under £9,000 including VAT for a Bioflo (I’ve also seen them priced over £11,000), with Multiheat boilers at just over £6,000 for a 15kW model and £7,000 for a 25kW version (although I’ve also seen them priced at more £2,000+ more) and Solo Innova at £4,800 for a 20kW model and £5,300 for the 32kW model (again I’ve also seen these priced at around £1,500 more). Treco / Guntamatic Biostar boiler prices range from just over £11,000 to just over £14,000 (excluding VAT).

You’ll also need to pay for installation and a suitable flue if you haven’t got one already.

Pellets v Timber
Personally I’m not keen on the idea of pellets. Too proprietary and too vulnerable to volitile markets for my liking, but I can see their value as an alternative to oil or gas where a local source of timber is not available. Additionally, they take a lot of the manual labour away and reduce the time demands made by logs in their splitting, stacking and seasoning. Pellets also offer the convienience of hoppers and unattended heating. My ideal of a biomass boiler that will burn any type or condition of biomass seems to be some way off as the biomass boilers I’ve been reading about require, seasoned, sizeable, well prepared timber.

Costs and benefits
For comparison I looked up the statistics for my current multi-fuel stove. It’s a Charnwood Country 16B Multi-fuel central heating boiler with output statistics as follow:

• Space Heating Output (BTU) – solid fuel = 5.5kW (18,779) wood logs = 7.7kW (26,291)
• Water Heating Output (BTU) – solid fuel = 13.7kW (46,778) wood logs = 8.2kW (27,999)

This cost something over £3,000 fitted for 15kW or so of combined output.

At a guess I could get a 20kW Baxi Solo Innova installed for somewhere between £6-7,000 and if I wanted the full ‘hands-off’ luxury of a 15kW Biostar boiler I’d be looking somewhere around the £13-14,000 mark. So not cheap in comparison to more traditonal heating solutions such as my multi-fuel boiler/stove. The Energy Saving Trust (EST) tell me I can get a standalone pellet stove for £4,300 installed – I’m just not sure who from!

So how and why am I going to pay for this?
Treco claim that “Your fuel bill will drop by at least 30% when you make the switch from oil [to biomass]“ so there’s an immediate saving when switching from oil of several hundred pounds a year based on current fuel oil prices (and it looks like that saving is only likely to grow). Even with prices as they are, as of writing the annual costs of a biomass system are likely to be more that those of a mains gas powered system.

The main advantage in comparison to more traditional heating and hot water solutions such as wood burning are the relatively low amounts of ash and the opportunity for unattended operation. You can get that from gas (if you’re on the mains) or oil, but if you want a greener (albeit currently more costly) solution then perhaps a biomass boiler is what you need…

You may be able to get some financial support under the Renewable Heat Incentive, although as of writing details for domestic schemes will not be available until next year (2012).

Further information is available from:

http://www.baxi.co.uk/products/biomass-boilers.htm

http://www.treco.co.uk/domestic/domestic/

http://www.treco.co.uk/guntamatic/

It’s been mainly outdoor work this month thanks to the pretty good weather.

I completed the flag-stone patio and I’ve concreted a top onto the dry-stone wall that runs along one side of it. I have built my (not-quite-as-deep-as-I-planned) barbeque pit and started to build a flag-stone fronted raised bed at the bottom of the main garden slope.

I’ve not made much progress in the wood with clearing trees to let the sunlight in, having been diverted by cutting and splitting logs that were kindly donated from my neighbours wood-pile. Next winters fuel is hopefully pretty well sorted. An additional benefit is that I’ve managed to get my chainsaw cutting much more efficiently by a combination of sharpening the blade and figuring out the correct tightness for the chain.

Now I’m back on to pointing with just a couple of patches to finish and hopefully no interruptions from the weather. I nearly made a start last weekend, but wasn’t happy with the mortar mix which was too yellowy as I used a new kiln dried sand, so I used that mix to start pointing the garden walls instead.

I completed the retaining great wall at the end of the path at the back of the barn and got on with putting in a mortared masonary wall to the garden side of the path that leads along the back of the barn through the gap in the wall that was one of my first acts of destruction at the barn. I’m also rearranging the rock garden that sits above this wall – it’s quite hard to describe so I’ll post some pictures shortly. This work has started to tidy things up but there’s still plenty to do. I began to lay the flag-stone patio last weekend, but rain-stopped-play as it so often does.

I made a start on clearing some of the trees and branches from the thick hedge that runs along the south facing edge of our little patch of woodland to let more sun-light into the wood and to make a contribution to next winters fuel supply. A blunt chainsaw chain and poor weather put paid to completing this job at the end of the month. A set of chainsaw sharpening files and the cold but dry weather that’s hopefully around the corner should let me crack on in March.

I had a visit from building control that’s given me the need to review my to-do list (coming soon). I had a bit of a concern about safety glass, but thankfully the bedroom hayloft door glass and the glazed arch in the bathroom are safety glass (the little safety glass symbols were obscured when we were looking for them by the masking tape that had been on the windows since last summer). The need to establish if it was safety glass or not made me get on with painting the bedroom hayloft door and the large yard side window (the top of which forms the glazed arch in the bathroom) so that I could remove the masking tap so that’s some painting unexpectedly done.

Inclement weather drove me indoors a couple of times so the main bathroom has had more tiling done to tidy up the joints in the shower cubicle, the walls have had holes filled and a spruce up of the paintwork, I put up a couple of hooks for hanging clothes on with the aid of my new stud finder (for finding wall studs – essential to get a good sound fix to the wall) and all the tiling has been cleaned over again.

I was also visited by a family of fellow barn convertors – good luck to Debbie, John and family; I hope you found some inspiration!

TRF and I went for a walk in the woods on Sunday. It’s been a while since I’ve been there, except to dump ashes from the fire.

From Barn Conversion 2011

TRF told me that the brambles have been placed there by dragons – must be to keep us away…

There is plenty of growth in the hedgerow that needs to be removed to allow light in and for me to start to replenish my dwindling stock of firewood. That gives me a job to look forward to at the weekend, if I can get my chainsaw started. A job to get done before the tree sap starts rising and spring arrives. It would be nice to feel some warm from the ground again.

The ash logs that I get from my little patch of woodland need to be split to season properly – the unsplit logs that I cut last winter, despite residing in a nice warm metal clad shed all summer have sizzled as they’ve burnt…

There are one or two large branches that have fallen over the winter – a bounty of wood that doesn’t need to be cut!

From Barn Conversion 2011

I picked up on a few ‘nuggets’ of inspiration on our recent trip to Cornwall.

From Travel

From Travel

I’ve got quite a lot of raised beds to build both to the front of the barn and in the garden at the back. I’m toying with the need for solid breeze block or brick backed structures against ‘looser’, less permanent dry stone structures. These lovely raised beds, photographed on my phone (so apologies for the quality of the pictures) at the Eden Project sway me down the dry stone route.

From Woodland

I thought it worth taking this picture of a hurdle – I’ve plenty of ash and willow that needs tidying up and maybe I could ‘lash’ some of these together from the smaller branches with the larger stuff going for firewood.

From Travel

Not one for the barn, but this living roof took my eye (after dragging it away from the beautiful estuary in the background). Although I worry about leaks, having a living breathing roof seems like a good use of an otherwise ‘dead’ space (unless it’s crammed with solar or PV panels of course!). The wall and gate are pretty special as well, although the wall is too perfect for the barn – a little too neat, tidy and precise – too correct – it would both show up and look down on my more ‘organic’ dry stone walling.