Posts Tagged ‘Wood-Fired Boiler’

Shopping List – latest update

Steadily firming up the shopping list for our new house – here’s the latest list, with links. 

Kitchen

Dining Room

  • Expandable table

Playroom

  • Instant-heat to stand in front of (Gas?)

Lounge

  • Wood-fired stove
  • Central Pendant light in diffusing shade – 12v CFL?
  • Two Standard/Reading Lamps – 12v CFL?

Garden

  • Kitchen Scraps Compost: Black Soldier Fly Composter / Worm Farm 
  • Firewood store, and at least 12m³ of wood
  • Greenhouse with Aquaponics system

Heating & Hot Water

Power & Light

Water

Using a Wood-Burning Stove in a Smoke-Control Area

esse100seThis is something we need to work out – our new house will be in a smoke control area. To check whether you’re in a smoke control area look up your local authority here. If you are then the only wood or multi-fuel burning stoves you can fit are listed on the exempt appliances list. It also explains what types of fuel you’re allowed to burn in them.

There is a good collection of the usual suspects – Clearview models, the Dunsley Yorkshire range, several Rayburns and Morsos. And some I haven’t looked at before – Dovre, Hwam, some Stovax models, and Westfire. Stoves Online have a great list of their clean-burning stoves, with links to piccies and details

In a surprise, Esse do not have any models on the list, but a quick check of their site shows that they have just launched (9th Feb) a new model that is OK in smoke-free zones. It’s the compact 100SE model – as shown in the photo!

Wood-Fired Ranges in a PassivHaus

In my PassivHaus Renovation post I said that:

Any non-solar water heating to be Gas Condensing boiler or CHP – wood fired stoves are not permitted (this conflicts with my peak-oil resilience planning)

In return I got a comment posted by Andy Simmonds at the AECB stating:

The AECB standards do not proscribe wood stoves, nor does the german version of the PassivHaus standard.

I’ve been back to the AECB standards and here are the sections of the Proscriptive Standard that deal with heating & cooking:

Space heating (Silver Standard):

Normally radiators or underfloor pipes. Fed from SEDBUK A-rated mains gas condensing boiler, CHP or, outside the gas supply area, SEDBUK A-rated LPG or oil condensing boiler, earth-source heat pump (seasonal COP ≥3.0) or cleanburning biomass boiler; i.e, one using liquid or gaseous fuels. Wood pellet boilers are permitted outside the gas supply area but are not encouraged due to the exhaust emissions. Blocks of flats or maisonettes to have a central boiler and/or CHP plant or heat mains connection; i.e. heat distribution within the block rather than individual boilers or electric heating.

Space heating (Gold Standard):

Normally hot water coil(s) in ventilation ductwork. Circulating pump consumption ≤0.1 W per m2 floor area or pro rata; e.g., Grundfos Alpha Pro or equiv. Heat sources as for Silver.

Cooking (Gold Standard):

Hobs gas, LPG, electric induction or clean-burning biomass – liquids or gases only. Ovens gas, LPG or electric A-rated. Electric min. A+ or A++

I don’t see anything in there which suggests a wood-burner would be permitted? I’ll have a chat to Andy and see if he can clarify things for me!

How much firewood should you store?

Good Size Log Store

Good Size Log Store

Huge numbers of people are putting in Wood Burning Stoves, Boilers and Ranges at the moment. They’re doing this for a number of reasons: to beat rising gas and electricity prices, to reduce their carbon footprint,  or to improve the resilience of their heating system in the face of peak-oil based supply issues.  The first challenge appears to be actually getting hold of a stove – apparently Dunsley have a 6-month backlog on orders for some of their stoves, And Stovax reported a 50% increas in orders in the last quarter of 2008. Once you have your stove though, how resilient is it likely to be? Unless you have your own woodland you are dependant on a supplier – so will there be enough wood for everyone who is currently putting in a stove or range?

The Guardian recently discussed the problems there are with firewood supply, and there are some of the facts:

  • Current UK consumption is about 1,180,000 tonnes a year.  Only 1m of those are produced in the UK, so we’re currently importing 15% of our firewood needs.
  • However, if you’re not fussy about what you burn, then there are 2.5m tonnes of burnable wood going to landfill every year – so if you see a skip full of random timber or broken pallets take it home and burn it – you’ll be helping the UK become firewood-independant.
  • Demand is increasing at around 25-30% a year, and resulting shortages resulted in price increases of up to 30% at the end of 2008.
  • The increase in demand is particularly resulting in an increasing supply of green, un-seasoned logs that will need to be stored for at least a year before being burnt.
  • There are wide price variations across the UK firewood is most expensive in the North and West, and cheapest in the South East.
  • The Government is working to bring another 2m tonnes of firewood to market by 2020. They say this will be enough to heat 250,000 homes (an average consumption of 8 tonnes/yr/house).

With the current supply chain under significant stress, the easiest way to ensure that your wood-fired stove or boiler continues to provide heat is to make sure that you have stored enough wood yourself. The general guidance is that wood should be stored for a year to reduce its moisture content from the 70-50% it is when felled down to an ideal <25% for burning. If you haven’t been through a full season with your wood-burner yet the general guidance is that an average house will consume 8 tonnes a year – around 12 m³, depending on your level of insulation, how hot you keep the house, whether it’s also heating your hot water etc. So – how much wood have you got stored? Two months supply? Less?

If your wood-burning stove is essential to your heating/cooking/hot water then you need to take wood storage seriously. Build a wood store – a shelter with a roof (clear if possible), open sides, and use pallets for the base and to divide sections to maximise airflow. Preferably split it into at least two sections so that you can have one section “seasoning” (drying) and one section that you are burning. Store the wood end-on to the airflow after chopping it to the right size for your stove. Make the stack as tall, long and thin as possible to maximise airflow.

Do that, and your wood-burning range can provide a really resilient solution to your heating, hot water and cooking needs.

Resources

Bin your Aga – buy a Rayburn

 

An Esse, not an Aga

An Esse, not an Aga

George Monbiot in the Guardian is launching a campaign against the Aga. He reasons that they use a ridiculous amount of oil, and generate an obscene level of CO2. I have to say that I’m with him on this. You won’t find much about Agas on GentleDescent because once I’d done the basic research and found that you couldn’t get a multi-fuel version I realised they weren’t going to meet my post-peak-oil needs. The decision was helped by articles like this one in The Times about people ditching their Agas

 

If you’ve heard about peak oil at all then surely putting in an oil-fired Aga is profoundly stupid. It’s OIL-FIRED. So when oil runs short or is out of your price range then what are you left with?  A great useless lump of cast iron, and no heating or cooking options – not very resilient! If you have to buy an Aga then at least get a Gas or Electric version, but realise that you’re doing it as a lifestyle choice, it is not a resilient long-term option.

So what should you get? I’m still working that out! The couple in the Times article went for a wood-fired Esse with a back boiler.  Ive looked at some really beautiful wood fired stoves, and the Rayburn, paired with a Solar Thermal system, but I’ve yet to come to a conclusion.

But what should you do if you do have an oil-fired Aga already? Apparently their re-sale valus is terrible, so I guess if you were feeling optimistic you could convert it to Gas, which may last a little longer, and be a little more environmentally friendly. Twyford do official Aga Gas Conversions. Otherwise? Send it for recycling. And buy a Rayburn (probably).

Underfloor heating or radiators?

UnderFloor Heating- MysonAssuming we’re not going to be at the point of only heating one room anytime soon, how do we heat the whole house? Traditionally I’d have said easy – just radiators. The hot water can come from our wood-fired range, topped up with Solar hot water  and our emergency Gas boiler. But I’ve always had a hankering for underfloor heating, so I thought I’d have a look and see whether it was possible , and economically sensible.

The efficiency figures are impressive – “wet” underfloor heating is 30% more efficient than radiators (you can also get electric underfloor heating but it is 30-40% more expensive to run than the hot water – “wet” – systems, so we won’t be considering those).

Wet systems work by running warm water through a network of pipes either under the floor or under the floor covering. The water only has to be about 50C, so it’s much easier to run with renewable sources than radiators are. You’ll also get back all the wall space usually dedicated to radiators, and benefit from not having your heating source trapped behind a sofa or right underneath a window.

I’ve always thought it’d be something you’d only fit if you were building new or replacing all the floors, but there are now systems that will fit on top of your existing floor, under your floor covering. This makes fitting them to an existing house a much more manageable proposition. You just need to ensure that suspended ground floors are insulated and that you don’t have too insulating a floor covering – make sure it is less than 1.5 tog.

How much will it cost? If you’re doing a whole house it’ll probably come in at between £12-16/sqm – about the price of a decent carpet, ro about the same price as a radiator system. So you probably wouldn’t do it to replace a perfectly good central heating system, but if you need all-new heating it should definitely be considered. They should last 25-50 years so it’ll be a good investment!

Other resources

  • Channel4 – a great discussion of all the options and issues. 
  • Myson – Manufacturer, will lots of great technical information on what’s possible, prices etc. Check out their great Technical Guide.
  • Polypipe – Manufacturer, includes details of their Overlay low-profile over-floor system.
  • SelfBuildABC.co.uk – great article on all the issues.
  • Borders Underfloor Heating – a supplier with diagrams of all the fitting methods for each floor type.

Rayburn Solar Thermal System

Rayburn Solid Fuel / Wood Cooker & Boiler
Rayburn Range

OK, so this is an interesting development – you can get a Rayburn Solid Fuel / Wooburning Stove & Boiler packaged with a Solar Hot Water System and twin-coil cylinder. They call it “The Rayburn Solar Thermal System”. Seems like an interesting combination for those of us concerned with both emissions and future fuel scarcity and resilience. For peace of mind I’d just need to add an electric or gas top-up to the system too . . .  

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