The greater majority of the wood pellet boilers being sold in Ireland do not have adequate “back-burn” protection.
What does “back-burn” protection mean?
In a wood pellet boiler the burner unit, where the flame is created, is connected to the supply of pellets via an auger and a piece of plastic tubing. (see above picture)
The purpose of the bit of plastic tubing is to “melt” if there is burning of the pellets back up through the tube through which they are fed, thus cutting off the pellet supply. In many boilers this is really the only separate back-burn protection.
If, for instance, there was a storm blowing with possible down draught in the flue, a backpressure might be created temporarily in the pellet feed tube. If this should happen for any reason, the pellets in the tube could easily and quickly ignite.
If the pellets should ignite in the feed tube, and really get going, the question is would the plastic melt fast enough to stop a fire?
Would you trust the bit of plastic tubing, (by implication, approved by SEI, as they approve the boilers) , to save your home or the lives of your family???
My guess is that all of these boilers will have to be retro-fitted with water quench safety devices.