Experience of wood pellets for heating??

[dickm]

We need to install radiator central heating in our house, which currently only has electric panels on 3 "off-peak" periods plus a small woodburning stove in the living room. It's a highly insulated, triple glazed timber bungalow, with mechanical ventilation and heat recovery, so the total maximum heat demand is only about 6kW. This meant that electric heating was probably sensible when it was built in 1999.
But we now need something different. Because we live pretty much in the wilds, the choice is really oil, heat pump or some form of wood heating (plus solar panels for warm water). Oil is cheapest to install, but won't be cheap to run. Heat pumps I don't want, because I reckon they are a total con (4:1 heat gain on the electricity used, but 30% generating efficiency means they really only provide about 1.3 gain on the original fossil fuel). That leaves wood. We want something that is easy to use (both OAPs, so we don't want to be chopping and lugging logs for the next however-many years). So that says wood chip or wood pellet with an automated boiler. Problem is, because of the low heat demand, wood chip is probably out because the smallest boilers are about 20kW. That leaves wood pellet. There are going to be 3 local suppliers of pellets shortly, so I'm currently leaning that way. BUT, would be interested to hear of any experience folks may have had with these.
ANY THOUGHTS?

 

[MikeG.]

Dick,

this really is my field! I have been studying this area for years, and also specifying wood pellet boilers for a while now.

I think I may know of your house.........if it is the one built of a double-stud construction. If it the one I think, I don't recall seeing a glazed sun-space (conservatory)??.... Did you build it yourself? I built a balloon-frame double-stud house (next door to me here) in 1995/6.

Firstly, I think your assessment of the alternatives is spot-on. Ground source heat pumps are glorified electric heating. Indeed, they are virtually the same as air-conditioners and fridges in principal (ground to water heat pumps instead of air to air heat pumps), and are in my view something of a green sham.

I have built a number of ultra-low energy houses with massive levels of insulation, triple glazing and MVHR units.........my own house costs about £40 per year to heat...... My experience is that you will spend a lot more of your energy heating the hot water than you will heating the house. Do you have solar panels.........you mention them, but only in a list of choices?

Space heating would be met comfortably with a well located wood burning stove. It would be met even easier if the house had a high thermal mass rather than the lightweight construction.

So, this boils down to heating your hot water. If you have solar panels, the UK average would be a provision of about 50% of your annual hot water demand met by solar panels, but any auxiliaryhot water system you put in has to be capable of meeting the peak demand.

Electric hot water heating would be very feasible, but even with a lot of the Scottish electricity being generated by hydro-power this will still be a nasty dent in your green credentials.

Oil.........ditto. In its favour is the relatively low capital cost and established network of suppliers. We all know what is on the reverse of that coin.

Don't even think about wood-chip at the moment. All the schemes I know of struggle with repeated breakdowns, and anyway, the high moisture content means quite inefficient combustion, and poor energy outputs per unit volume or weight.

Wood pellet, then. Well, to my mind this is the technology of the future. It is used successfully at domestic level all over Europe, and is the only way I can see of developers achieving Gordon Brown's target of zero-emissions houses by whenever he said.

The fuel is clean, flows like a liquid, dry and uniform, and contains very little embodied energy (from manufacture.........transport to Scotland may be problematic, as I know of no suppliers up there). It can be bulk transported, although most suppliers at the moment seem to be concentrating on pallets of bagged pellets. The fuel is a bit cheaper per unit of heat output than oil currently is, if my maths serves me correctly.

The machines are pretty reliable, but you will need service back up, and whoever supplies your boiler should give you a service agreement as well. They should also keep a spare burner in stock at all times. They can be noisy, with a tick-tick noise going on all the time, and the auger pumping the fuel could drive you nuts. I would certainly build a lean-to on the outside of the house for the boiler and the fuel. There is obvious benefit in retro-fitting a Class A flue up the outside of the house, rather than trying to get one through an existing roof..........but obviously you won't benefit from additional heat-gain from the warm flue. The machines are very low maintainance.....most clear their own ash.......and fully automated. You won't be fiddling with it every day as the old solid fuel boilers required.

The real downside is the capital cost. A straight forward system I just specified has been quoted at £9000ish, including a hopper and the auger. (If it wasn't for a house with a build cost of over £800,000 I'm sure they would have installed oil instead).

The pellet boiler will also be too big for you property. That doesn't really matter I don't think, except that you are paying for capacity that you wont be using. If you do go for one of these, I suggest not importing one yourself direct from Europe, but buying through a local dealer who can at least try to provide some servicing back up.

If you do go for a pellet boiler, then it will of course supply all your heating and hot water requirements, and there would be no need for a wood burning stove.

I look forward to hearing of your progress, and wish you well. If you do go for a pellet boiler, you will be something of a pioneer, and as such must expect that there will be the odd issue along the way...........be re-assured that a huge mass of people are going to be following your footsteps very soon!

Mike

 

[Mcluma]

If you are getting old etc etc, you need something reliable. you do not want to mess about, and something that is safe

If you are not willing to go the oil route, then go for the gas route

The equipement is cheaper, and is servicable by everybody

so just put a LPG tank in the garden en your are done

 

[SketchUp Guru]

Don't know if this is of any use but my coworker just bought a pellet stove to at least supplement if not replace the heat from his LPG-fired furnace. He figured that if the pellet stove is his only source of heat, the payback will be about 2-1/2 years.

 

[MikeG.]

Dave,

for the avoidance of confusion, you do mean stove, do you........rather than a boiler?

If so, there is a vast difference!

Mike

 

[SketchUp Guru]

Dave,

for the avoidance of confusion, you do mean stove, do you........rather than a boiler?

If so, there is a vast difference!

Mike

Yes, I know there is a difference, Mike. I did mean stove. Like the one in this picture.

My point was that here, in the US, the cost of pellets is enough lower than gas, that the payback is relatively fast.

 

[dickm]

Thanks, Mike, for that excellent response. I actually went to a local seminar on wood heating yesterday, organised by Highland Wood Energy, where they were pretty persuasive about wood heating for larger installations (the meeting was aimed at business, but there were several of us interested in smaller domestic kit)
I was assuming adding solar w/h to whatever system we installed, in spite of what RICS said today, and would be putting the boiler the other side of our drive in a cabin of some sort. The system that takes my fancy is the Oekofen, but I heard a bad report yesterday of their local agent, and the main importers are in Welshpool (only 450miles away ).
Any advice/experience of the various wood pellet <boilers> would still be very welcome, as there seem to be quite a number on the market now. All imported, of course, but one day we will catch up with Continental Europe
(ducks the flak from the Eurosceptics)

 

[MikeG.]

Dick,

this is yet another area where we lag years and years behind mainland Europe.

I'll look out the details of the boilers I have been specifying..........that just feels too much like work at this time of the evening though!!

Mike