Biomass boiler flue cleaning

How often

There isn’t one answer. Wood chip fouls differently from pellet, wet fuel differently from dry, and a boiler running flat out all winter needs more attention than one covering a summer hot-water load.

Most of the plant we look after is on a six or twelve-monthly clean. Some sites alternate a full clean with a lighter interim clean six months later. If we find heavy tarring, we’ll recommend bringing the next clean forward rather than waiting for the cycle.

Why it matters

A fouled flue costs you twice: in fuel, because the plant has to work harder, and in the flue itself, because deposits hold acidic condensate against the wall. Most of the corrosion we find is on flues that went too long between cleans.

Your insurer, your boiler manufacturer or your maintenance contract may also expect documented flue cleaning. Our reports are written so they can go straight into that file.

Every visit is written up

Each flue gets a condition score out of 100 across five areas — soot, obstruction, liner, structural integrity and defects — with photographs from inside the flue. Each boiler gets its own certificate, and a sticker on the boiler shows when it was last cleaned and when it’s next due.

Because the scoring is the same every visit, you can see a flue getting worse over a year or two and plan the repair, rather than finding out when it fails.

See an example report — it’s for a made-up site, so you can see exactly what you’d get without anyone else’s details on show.