ETA wood pellet boiler

The ETA PU, PC and PEK wood pellet boilers are available in thirteen sizes, ranging from 7 kW to 499 kW, and incorporating all the latest biomass heating technology. At 92-96% efficiency, these are some of the most efficient and automatic pellet burning boilers made in the world to date. 

Link to ETA website

The current ETA wood pellet range allows for installations of up to 1 mW using a cascade configuration. In December 2014 the long awaited Hack 499 pellet was launched offering class leading performance in efficiency and low emmission levels.

ETA wood pellet boilers are amongst the most efficient and controllable on the market and have received many awards for quality and reliability. The ETA PU, PC and PEK ranges come as standard with:

Draught fan

Unlike many biomass boilers, the PU, PC and PEK boilers come complete with low pressure draught fans. The fan is located at the rear of the boiler, drawing air through the boiler, which ensures a negative pressure inside the boiler at all times; by keeping a negative pressure in the boiler, the primary and secondary air can be regulated with precision.

Lambda control

Wood pellets, despite set standards, can vary significantly. Whilst wood pellets should have a consistent moisture content and size, they are manufactured from many species of timber, and therefore have different calorific values and burning characteristics. By monitoring the residual O2 in the flue gasses, the wood pellet boiler regulates the amount of fuel fed to it. The wood pellet boiler also regulates the amount of primary and secondary air in the combustion chamber to ensure a very clean burn, with a high furnace temperature and complete combustion.

Rotary valve

Each ETA wood pellet boiler is supplied with an air tight rotary valve. On the smaller wood pellet boilers, an integral hopper is built into the body of the boiler, which holds enough fuel for 24 hours burning. On the base of the hopper there is a small six-way brass rotary valve to ensure no air can leak into the furnace, other than through the motorised air flaps. On the large boilers, the single chamber rotary valve is used.

Automatic ignition

All ETA boilers are supplied with automatic ignition as standard. When the boiler senses a heat load, a small amount of fuel is augered into the furnace and the hot air ignition fan restarts the wood pellet boiler. If there is no heat load from the system, the biomass boiler will sense this, and go into a controlled shutdown. 

Automatic de-ashing and Turbulators

The turbulators are located in the heat exchanger tubes in the rear of the boiler. Unlike with the log boiler, these turbulators are operated by a motor on the side of the wood pellet boiler. The  pellet boiler monitors the amount of fuel burned, and at a preset amount it will carry out a de-ashing cycle. Inside the boiler furnace there is a tilting grate, which will turn over 90° and remove any clinker and ash into an auger, which then removes the rubbish to the ashbin located on the front of the boiler. The turbulators move up and down in the heat exchanger tubes, removing any fly ash from the exchangers and keeping the boiler working at peak efficiency. The fly ash is also taken by auger into the ash box.

Accumulator tank management

The ETA wood pellet boiler comes complete with an accumulator tank management set. Two sensors are installed in the accumulator tank, so that the boiler knows how much energy is stored in the tank. The boiler is set, either to maintain the tank at a set temperature, or to shut down when the bottom of the tank reaches the desired temperature.

Heavy construction

The main body of the ETA biomass boiler is made from thick mild steel; inside, the combustion chamber is made from fire brick to ensure a long, trouble-free life.

Remote fuel hopper

Due to the relatively consistent size of wood pellets, they can easily be moved by a fan. ETA wood pellet boilers come complete with, either an auger base set (around which a plywood store can be fabricated to fit into a garage corner, loft, or any other free space), or a bag silo, available in two sizes: 3 tonnes and 5 tonnes. The wood pellet boiler is linked to the store via two flexible 50mm pipes; at preset intervals a fan located within the body of the boiler will start, and draw pellets from the bulk store to the small hopper inside the boiler.

Cross section of ETA wood pellet boiler

  1. Tilting grate
  2. Primary air actuator
  3. EGR (Exhaust Gas Recirculation)
  4. Hot, ceramic-lined combustion chamber
  5. Secondary air actuator
  6. Flame room
  7. Heat exchanger with cleaning turbulators
  8. Ash screw for ashes from the grate
  9. Ash screw for ashes from the heat exchanger cleaning
  10. Removable bin for ashes
  11. Draught ventilator
  12. Control board
  13. Insulating front door

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