Biomass boilers are unreliable

Photograph of a damaged ash can

Biomass boilers are unreliable!


I’ve had a bit of car trouble lately myself. I took my car back to the dealership last week and had a word with the mechanic there. Told him the damn thing hadn’t been running well since I started putting paraffin in the tank instead of diesel, and he looked at me like I was a lunatic.

“Why’d you do that?” he said.

“Well it was cheap,” I said.

“When’d you last have it serviced?” he said.

“It needs servicing?”

“Yep,” he said, “Especially if you run it flat-out everywhere and put a hundred and fifty tonnes of crap fuel through it in the space of a year.” He kicked the bare wheel rims. “Where are your tyres?”

“Oh,” I said, “Well they gradually went down and then one after the other they fell off. Corners really badly now…”

He leaned over the engine and withdrew something from the murky depths. “Your dipstick is dry — you’re running it without checking the oil?”

“Ah, that reminds me,” I said, “There’s a really tedious little red oil can symbol that keeps flashing on the dashboard — is there a way to turn that off? Bloody annoying! I’d stick a bit of tape over it, but I can’t be bothered….”

Not to stretch the metaphor too far, biomass boilers require a little bit of TLC. Just a little bit. Keep it clean. Run it on the correct fuel, make sure it’s decent quality fuel, check the seals when you empty the ashcan. If there’s black smoke pouring from the chimney whenever the boiler is running there’s something wrong — call your installer. Don’t leave it until it causes a problem. We are just at the other end of the phone and happy to help.

Photograph of a damaged ash can

Damaged ash can

Damaged ash can with notes

It’s obvious when you know what you’re looking for

As you can see from the above image, the lid seal for the ash can is hanging down the front of the ash can. This is no doubt where the problem started. The gardener empties the ash can and (I don’t think he particularly wants to do it) he hasn’t noticed that the seal has come away from where it is supposed to be.

Biomass boilers achieve their high efficiency by carefully controlling the amount of oxygen that gets to the burning chamber. The wood gassifies, the gas burns, then finally the carbon burns until all that is left behind is a very fine ash. If too much air goes through the boiler because of a misplaced or damaged seal, the fire roars away, gets too hot, melts the ash into something resembling volcanic glass, which chokes the grate, which further interferes with the burning efficiency.

With this one you can also see unburnt pellets on the floor underneath. This can indicate that the boiler is not operating correctly. In this case the unburnt pellets have come through into the ash can, where they normally would have been starved of air and not combusted, but here, with the seal out of place, they burned with a ferocity enough to melt the handle from the box, burn off the paint and warp the can where it mounts onto the boiler, thus letting through even more air.

The chimney was issuing black smoke like a red indian signalling Custer was on his way.

Regardless of all this, the obvious faults were ignored until the boiler stopped working altogether. Does this mean the boiler is unreliable?

Our first Hack 200 is still working very nicely at Savage Cat Farm. It has done 5,923 full load hours since it was commissioned. It doesn’t have flue gas recirculation – doesn’t need it. All it burns is round wood seasoned and chipped on the farm. It gets serviced every 2,000 hours and cleaned by the farm manager once every six weeks and maybe gets an ash can empty in-between time. The boiler has never broken down, never given anybody a minute’s trouble. I call that reliable. You don’t tend to hear much about that sort of thing, but then bad news has a habit of travelling farther and faster than good news, I find.

Look after your ETA biomass boiler and you will find it as reliable as an oil boiler.