If you are finding that your pellet boiler is burning more pellets and costing more to run than you expected, then please read on.
One of the key areas to focus on is how well the wood pellets are burning inside the boiler. The following are all signs of poor combustion:
- Pellets burning out fast
- Partly burnt pellets in the ash
- Blackened but still complete pellets in the ash
- Excessive amounts of either:
- ash output
- clinker on the grate or in the combustion chamber
- build up of soot and tar in the flue
The issue can often be related to the boiler itself and it’s worth making all the obvious checks (such as ensuring the combustion chamber is clean, seals around the door are sound, air holes are clear, pellets feeding in at the correct rate etc) and having the boiler properly serviced.
If this does not make any difference, it’s then worth looking in detail at the pellets you are using. Key things we see going wrong are:
- Slightly damp pellets (normally obvious if the pellets are starting to swell up)
- Excessive dust in the pellets
- Fines (small particles of broken pellets)
- Low calorific value (CV)
All of the above are normally as a result of poor pellet manufacturing, handling or storage. They will all lead to excessive pellet consumption as the boiler typically tries to compensate for the pellet deficiencies by increasing the burn rate.
Excessive dust and fines leads to clinker and often temperature “hot spots” on the grate. Damp pellets tend to fall apart and reduce the heat levels in the combustion chamber as the water content is driven off or jam the pellet feed. Low CV pellets are normally a result of poor feedstock going into the pellets in the first place.
When pellets are made they need to meet a certain density to ensure that they actually stick together for the duration of the journey from the factory to your boiler.
It is therefore no co-incidence that the further they travel and the more they are handled, the more they are liable to fall apart and the higher the dust and fines content tends to be.
One of the fundamental reasons for increased running costs of your pellet boiler is the use of low quality wood pellets that aren’t capable of producing the amount of heat expected. These have a high level of waste in terms of dust and fines and increase the wear, tear and maintenance on mechanical parts.
Knowing what is a high quality pellet and what isn’t can be difficult but at Land Energy we publish our monthly quality reports that allows you to compare ours with our competitors, take a look below.
