Pellet burning boilers.

[Bowers Hill]

Hi,

Does anyone have experience of wood pellet burning boilers? I am considering swapping my old oil burner for a system based around pellet burning along with solar water. It will be relatively expensive to install but I'm hoping that over the years it will pay off. What does anyone think or have experience of?

Thanks,

Rob.

[boboff]

We spent £25,000 on one at the new build learning centre, and it's just been decommissioned to be replaced with Emersion heating Elements.

The problems were.

1. Pellet Storage and delivery to the compustion unit. Both the level of dust and moisture content varies which means the system need tweeking all the time, with only volunteers available this did not happen.
2. It needs cleaning out a couple of times a week.
3. Nobody really understands the system and the spec, we were told many times that the new build was too well insulated and that the boiler was overspecked and was designed to work harder, then told the boiler was not up to the job etc etc.

We are looking at selling the hoppers and the combustion and control gear if you want?

I would say that you need to treat it very well as a system, and get to know that you can maintain it, and it takes ALLLLLLOOOOOOTTTTTT more time and mainetenance than a normal system.

Or we bought a crap one, one or the other.

There was a £1.2 million Tamar Valley Centre with one put in as well about 3 years ago, which I believe has gone to mains gas now......

[Bowers Hill]

Thanks,

My system would cost about 6.5K and then the solar on top. It's got a 70kg hopper filled by hand.
Filling and cleaning isn't too much of a worry it would just be an extra after feeding livestock etc.

I'll certainly look more into the moisture content and constant tweaking.

How big is your system and what make?

Thanks again,

Rob.

[boboff]

Sorry I don't know.

I am dubious about the green credentials of these boilers, especially given the enormous premium you pay on standard installation and the fact the fuel isn't cheap and the cost is linked to Oil and Gas in any event. (through supply and demand)

[gdb]

My house (Sweden) is run by a pellet CH boiler.

Overall I rate it pretty highly.

They give a very good heat - comparable to oil CH. Do all the hot water and so on too. And, with a medium sized hopper, you only have to load it once a week. (A little more often in the really cold winter). Cleaning is done about once a week with a small industrial vacuum. Pellets are much less of a chore than wood burning CH.

The downsides: first off, as Boboff mentions - is pellet storage. They get delivered over here in pallets of about 60 sacks. And that means you need a good big dry indoor space to store them. (Not a problem in Sweden as all houses have big cellars). Secondly, if you are a bit frail or ill or whatever, and your hopper runs out of pellets, who is going to load them for you? Although each sack is only 16kg to 20kg by the time you have moved a score of them you have pretty sore arms.

A boiler here, that can run with pellets, electric and wood combined costs about 8K to buy. And the extras for the pellets (burner, hopper, screw and so on) take the total up to around 10K. (Dont quote me on those prices, I may be out by a good 20% or so).

[gdb]

I should add, in the summer they are very very good. A sack of pellets will give you two or three days hot water. Which is about as cheap as you could wish for.

(Oh, and no issues at all with tweaking. Once it's set up it more or less chugs away by itself. As to moisutre and so on in the pellets, the answer is simple enough: buy the best quality ones you can afford. If they are no good, buy the next best. DONT buy the cheapest and DONT be tempted to make them yourself or you will spend forever and a day doing that very tweaking that Boboff mentions!)

[Bowers Hill]

Thanks for the posts. I'm pretty sure that I will go with the pellet boiler but all the suggestions of points to watch out for are welcome. I may leave it until next year to see what RHI payments look like however I may lose the £950 payment then!

I've been going around the house and I'm thinking it best to spend some money bringing all insulation etc up to the best I can first.

Rob.

[EcoSam]

A lot of the problems with biomass boilers come down to correct sizing (in order to get the best efficiency) and the quality of the pellets... Here in the UK suppliers tend to use all sorts of rubbish stuff and I've heard of people finding nails/screws in with their pellets. Often they're not dried sufficiently as well. Best thing to do is find a reputable supplier and go visit/talk to them about their processes. In terms of embodied carbon, you need to source your pellets as close to home as possible (as long as they're good quality) cos, if you're concerned about carbon emissions, importing from Russia, Scandinavia or elsewhere your carbon footprint is obviously going to be higher.

An example of a good UK supplier is Esgair Timber based near Machynlleth, Powys who create their own pellets/woodchip on site from waste wood from milling and dry in their own kiln. They only supply people within 40 miles of their sawmill though.