Ten things *this* installer will tell you about biomass boilers (Part 1)

Biomass cabin under construction

Biomass cabin under construction

Biomass cabin under construction

I was Googling ‘biomass boilers’, which is what I do to relax on my days off, when I came across a blog called greenwisebusiness.co.uk that appears pretty high on the first page. The subject of the article is “10 things your installer won’t tell you before you purchase a biomass boiler.” The author, Louise Bateman, had a very bad experience with her pellet boiler and the installer who was supposed to be looking after it.


#1 on the list says the installer will either overspec or underspec your boiler, which I assume means under or over size. That’s down to the individual installer to get right. The same thing happens with oil and gas boilers — it’s not peculiar to biomass boilers, so please don’t tar all us biomass installers with the same brush.

This is one of the perceived problems that will be addressed in future rule tightening for the RHI. New rules will gradually creep in as they did with solar PV, requiring Energy Performance Certificates and the like before you can apply for RHI. No doubt sizing will come under scrutiny in the first round of changes.

It’s currently possible to ‘RHI chase’, which is where a boiler too small for the job is used to provide heat that has to be topped-up by other means. This keeps the installation cost down while still bringing in the higher rate tier 1 money from the RHI. Ethically, this treads the line, though it’s not wholly within the spirit with which the RHI was first conceived. It’s a phenomenon created purely by the banding. Generally this tends to happen around the ‘Small biomass’ installation threshold, which is 199kw. If you could do with another 50kw and fit a 250kw boiler you go into ‘Medium biomass’ rates, which ostensibly drops your RHI payment by about 40%.

On the other hand, a boiler too big for the job can be specified by unscrupulous installers for the purpose of making the Tier 1 band look more attractive to the customer.

For instance, if you needed a 100kw boiler the Tier 1 would be 1314 hours at 100kw, which allows you to claim 131,400kw hours @ £0.088 = £11,563.20 per annum. Whereas if you went for a 199kw boiler Teir 1 would be 1314 hours at 199kw, which is 261,486kw hours @ £0.088 = £23,010.76 per annum, which looks a lot better and seems like a good earner, but it isn’t, because you will never use the heat, so you won’t be able to claim all of your allotted Tier 1.

The temptation will be there to throw open all the doors and windows and burn, burn, burn. Not good when you consider the whole point of the RHI is to be green. I’m surprised the government haven’t clamped down on that already. Ideally you want your boiler to be just the right size or very slightly bigger so that it can cope with a prolonged cold spell. On dwellings this is easy to achieve by calculating the heat losses from the building. On commercial buildings it’s often a little more tricky because of ventilation factors, but even then it’s possible to get close if you can get all the data needed to make the calculation.

Note: RHI tariff correct at the time of publication. The rate has been cut since.

#2 on the list says the boiler will break down frequently. I sympathise with her on this because there are few things more miserable than living in a cold house, so her tenants must have been bending her ear night and day, and if there isn’t anything you can do to fix the problem because the only company you can look to for help doesn’t have the part to fix it, that’s really frustrating.

When I first got involved with biomass boilers, anybody who knew anything about them would tell me what a nightmare they were. The analogy was that they were like owning a classic car that you were going to take on a long trip — there was little to no chance you would get to where you were going without breaking down, and you would sure as hell need to take a tool kit with you, even if you were just going down the shops.

I used to own a Triumph Spitfire — I remember it well — I think they must have rolled out of the Leyland factory with a toolkit, Haynes Manual, an oily rag and a tub of Swarfega as standard equipment in the glove compartment.

The first UK built biomass boilers were based on old anthracite burning boilers with a big Archimedes screw pushing wood chips or pellets instead of coal. Real Heath Robinson looking things with a wax plug fire control mechanism that would flood the boiler with water if the plug melted.

They were unreliable to the point where it became something of a hobby to keep them going, which is fine if you’ve got nothing better to do with your time, but the very last thing I want to have to think about is heating my house when I’m cold.

I did a training course a few years ago where five of us oil and gas fitters from different firms were set the task of getting a pellet boiler fired-up. This rectangular lump of blue poo was marketed by a British company, who shall remain nameless, but I’ll give you a clue that it begins with the letter ‘B’ and rhymes with taxi.

Between the five of us there existed a good century’s worth of knowledge and experience in boilers, both domestic and commercial, but this thing was like a science project gone horribly wrong. After twenty minutes of head scratching and button pushing, screens of nonsensical options, etc., etc., the mood turned from frustrated amusement to one of  outrage.

Really? Had we Britons gone from the Heath Robinson Mk1 derivative of Stephenson’s Rocket anthracite burner, to this over complicated box of bolts with all the user friendliness of the Large Hadron Collider at Cerne?!?!

overly complicated pellet boiler

How’d you turn this thing on?

I think we peaked in engineering skill as a nation at around the same time we stopped shoving children up chimneys. Somebody must have pressed something right on that boiler, because it whined into life, briefly. A bit more tinkering got it making other noises. Then it started chuffing.

A few seconds later, with a sound like the crump of distant artillery, it exploded. Thankfully the fireworks were confined within the casing, apart from the fireball that issued from the flue to outside to singe a passer-by. Smoke leaked from the steel panels in cloudy lines which sucked back in for another internal blast, then poured out again.

Everybody backed away. The lecturer remarked, “Well, it’s never done that before.” I expect Mrs Hitler said something similar about her Adolf, but I still wouldn’t have wanted him as a house guest after he invaded Poland, would you?

(Don’t mention the war, Pete… you’re fitting Austrian boilers)

Their boilers may have improved since that model, I don’t know, but I’m guessing Louise Bateman’s boiler was of that ilk, because she says it’s been installed for eight years, and there wasn’t a terrific amount of choice in the field of pellet boilers back then in the UK.

There was another boiler on the market, we will call it Peckerwood, (*) which used to brag in its advertising that they were the only truly British biomass boiler on the market. They haven’t done that lately. I’m not sure what the reason for that is (apart from them going bust again), but even back when they said that, their big commercial boilers came from the land of the Skoda, and I was under the impression the rest were from the Irish Republic. I wouldn’t have said either of these countries is known for their engineering prowess.

We have just been called-in by a management company to give an opinion and offer suggestions on how several problematic biomass installations could be rectified. These were large projects given wide publicity over the last couple of years and now, just months later, they are dead in the water. Nobody wants to take on the service contracts and the boilers are either turned off or soon will be. The manufacturers have apparently ceased trading and parts are going to be in short supply.

Not so great when the boiler is heating over fifty houses and cost over a hundred thousand pounds to install.

The point I’m trying to make here is that there are boilers, and then there are boilers. Before buying, look carefully at the heritage of the boiler, and consider what people who own them say about them. Look at the sales figures in other countries that have a history of using biomass over the past twenty, thirty years.

ETA is the biggest selling biomass boiler in Germany — that’s got to tell you something. There are only five or six really good makes, in my opinion, and they’re all from Germany, Austria and one of the Scandinavian countries. I’m yet to be persuaded otherwise. There are new ones popping up all over the place, though. This may change.

#3 on the list is about the biomass boiler requiring considerably more time spent on it to ensure it runs efficiently and gives long service, this in comparison to a gas boiler.

That’s slightly subjective in nature, because we each have to agree on what constitutes a considerable amount of time, but it is true to some extent. I fitted a Worcester (Bosch) gas boiler in my last house, which was still going strong eight years later, when I sold the place, and all I ever did to it was put a flue gas analyser into the flue once a year and do a soundness test on the gas supply.

The place I’m living in now has an outdoor oil combi, manufactured by a British company who will remain nameless, but it begins with ‘G’ (and you’ll see a pattern forming by the end of this paragraph), which I put in twelve years ago and gave me quite a few problems until I gave up on the crappy hot water part of it, made it into a system boiler and installed a unvented cylinder to do my hot water.

Nevertheless, since doing that, I service it occasionally and, apart from having to remember to buy oil once a year, I don’t have to think about anything, don’t have to do anything to make sure my family stays warm.

With a biomass boiler you have to put in a bit of effort and, frankly, if it wasn’t for the RHI payment I don’t think I would bother for my house.

But there’s a BUT — a big one. If somebody told you they could knock 30% off your oil or LPG heating cost and hand you a few grand a year, index linked, guaranteed for the next twenty years, you might ask, “What do I have to do?”

The answer to that, in the case of an ETA pellet boiler, is open the door and scrape the ash from the inside of the boiler once a month (less than five minutes and very little effort), empty the ash can once every two or three months (depending upon the time of year), and order pellets when you need them. That’s all you have to do over and above what you would do with a gas boiler, unless you count reading the meter once every three months, posting it on the government website and cashing a nice big juicy cheque.

The yearly service is a little more involved than a gas boiler — the flue has to be swept, change a few seals, bit of grease here and squirt of oil there.

Chip boilers are more work, because it’s usually down to you to load the chip into the bunker, and if you’re buying it in already chipped you can suffer poor fuel quality.

Log boilers take the most effort, because you have to physically load the boiler with 18″ long logs once a day (maybe twice in a cold spell), as well as keeping it clean and splitting the logs. Personally, I picture myself with a bout of man flu, shivering, feeling like death on legs and still having to load the boiler before I can take a shower or warm myself on a radiator.

Not for me.

That said, we have fitted a few over the last year or so. They are cheap to buy and people who have them seem to like them. We’ve got one heating our workshop.

The wood doesn’t cost us anything, because we burn the pallets the equipment comes on and some joinery waste from just up the road. So we get our workshop and offices heated for free, plus we will get a £5,700 per annum cheque from the government. Payback on installation cost varies from three to four years, then you pocket the cash for the next sixteen years.

#4 continued on this page (*) Peckerwood Wiki definition: Peckerwood is the inverse of the word woodpecker. In most parts of the country where the word originated, the woodpecker is considered to be a pest and or nuisance.