Top ten questions of a new biomass boiler owner (ETA boiler FAQ)


So you’ve bought this new biomass boiler and it’s a bit like your honeymoon. It’s all exciting and new, and just a little bit disconcerting. You’ve told your friends about your shiny new toy and you’re proud of it. But it’s got a dangly bit here or a hidden button there that you don’t really know what to do with. A strange habit or two that you hadn’t noticed before. There are new sounds and smells that didn’t seem to be there on the display model. Sounds like you might need some Biomass Boiler FAQs answered. 

Does this sound like your life?

Never fear. There’s no need to ring your parents and beg them to come and get you. Well, at least read our Biomass Boiler FAQs first, anyway…

  1. Q: The screen is blank — is it broken?     A: No — touch it gently with your fingertips and it will spring into life.
  2. Q: It’s sitting there saying it’s ready, but nothing seems to be happening, should I worry? A: No — not unless everything’s gone cold. The boiler doesn’t have to operate all the time to keep up with its duties. Once the buffer is depletes to a set point the boiler will restart.
  3. Q: It’s saying ‘Ember burnout’. Is this the biomass equivalent of a nuclear meltdown, where the core of the boiler becomes molten. It’s super heated and then it melts through the bottom of the boiler and burns a hole through the Earth and ends up in Australia? A: No — calm down. Gravity will prevent the molten core of your boiler reaching Australia. Actually, no. It just means the boiler is burning what’s left in the combustion chamber without topping it up with more fuel. The boiler will typically do this before it de-ashes itself.
  4. Q: What’s de-ash? A: It’s de grey stuff in de bottom of de boiler. The boiler will automatically de-ash after burning a set amount of fuel. You can also force the boiler to de-ash prior to you emptying the ash can. Turn off the boiler on the screen, then press the de-ash button on the screen just above the on/off button. Wait a few minutes until you see the words de-ashing on the screen, then do your manual clean if needed. When the de-ashing interval is over, remove the ash can, empty it, check the seals and then replace it. Press the ‘on’ button to restart the boiler.
  5. Q: What’s that clanking noise when the boiler is de-ashing? A: That’s the turbulators cleaning the flue ways. The turbulators are like long metal pig tails. They get lifted up and dropped in the flue ways by the cleaning mechanism to dislodge any fly-ash.
  6. Q: There’s a funny message on the screen saying ‘ash auger over current’ — what should I do? A: Empty the ash can — it’s probably full of ash. Don’t worry, you haven’t damaged anything by your tardiness. If you empty the can and clear the fault message and it still happens, chances are you have a wood chip boiler with rocks in the fuel. In this case we may have to manually clear the auger.
  7. Q: I haven’t emptied the ash cans for weeks, months even, what’s going on, where’s it all going? A: If you’re burning good quality fuel, especially in the summer months when heating demand is low, this is normal. Typically ash residue of between 0.5% and 2% of the fuel volume you can expect, meaning best case scenario — 10 cubic metres of wood pellet (approx 6.5 tonnes) becomes 0.05 cubic metres of ash, or a twentieth of a cubic metre. Worst case scenario it becomes 0.2 cubic metres of ash, or a fifth of a cubic metre.
  8. Q: I’m having to empty the ash can every couple of days — what’s going on? A: Bad fuel and/or air leaks. Although the chip boilers can burn a wide ranging quality of fuels, you only get out what you put in. If you are running on chip and the wood has been, for instance, standing dead wood that has been felled, stored in the rain and then chipped, the calorific value (amount of heat you can get out of it) per tonne will be very low. The boiler will burn loads of it trying to achieve the desired output, creating a disproportionate amount of ash. Likewise, if you burn miscanthus, the output of the boiler drops 30% and you will be emptying the ash can for a pastime. Air leaks in your boiler, around the doors, service hatches, or more often, ash can lids and seals, can result in incomplete combustion of the fuel, resulting in more ash and a loss of boiler performance.
  9. Q: I want to turn off the boiler, but it carries on working after I’ve shut it off, so I’m going to hit the switch and turn it off oldskool style — is that OK? A: No, bad idea. If you want to turn off the boiler, use the on/off button at the bottom right of the touch screen. You will see the boiler cycle through screen messages ’emptying stoker’, then ’ember burnout’, then it will read ‘switched off’. The reason for this is the boiler needs to empty the stoker auger of fuel to prevent the fire from the combustion chamber burning back into the dropshaft and potentially spreading back through the fuel transport system into your store. The likelihood of this happening is very low with the unique and patented ETA rotary valve, but it’s best to be on the safe side. In addition, turning off the boiler also turns off all the pumps and safety devices that stop the boiler from overheating. It needs to carry on working for a while to safely dissipate the latent heat within the combustion chamber. If you must turn off the boiler by the main switch make sure the boiler is stone cold before you do so.
  10. Q: I’m about to strangle my mother-in-law — can I dispose of the body in the biomass boiler? A: No, and you really should seek counselling, you know. Each boiler, in order to comply with emissions legislation and RHI regulations must only burn the fuel that it states on the emissions test certificate for that boiler. If the RHI inspectors catch you burning the wrong fuel you run the risk of being permanently off the register, thus losing your subsidy. In addition, you will invalidate the manufacturer’s warranty, so I suggest you learn to tolerate your mother-in-law like the rest of us.

If you are reading this Biomass Boiler FAQs for research purposes I hope you found it informative and entertaining. If you have any comments, good or bad, or would like to enquire about having a boiler fit or serviced by us, or you need to claim on your ETA 5 year warranty regardless of which company installed your boiler, please click on the contact page link and send us your query.