Cleaning the boiler
How to clean a UNI 60 — ash removal, scraping the furnace and loading chamber, clearing the combustion air ducts and brushing the heat exchanger.
Every millimetre of soot and ash between the fire and the water costs you efficiency, so cleaning is not housekeeping — it is fuel economy. Shut the boiler down from the mains before starting.
Isolate and cool first
On all repair, maintenance and cleaning work, shut down the boiler from the mains. Let the boiler cool before opening it up — opening doors on a hot boiler causes burns and can damage the lining.
The four surfaces
Ash — every day
Remove the ash from the boiler daily. The ash pan sits outside the unit at the front of the ash door.
Ash banked against the grate blocks primary air and pushes the fire into smouldering — which is exactly the condition that tars the chimney.
Furnace and loading chamber — weekly
Clean and scrape the surface of the furnace and of the loading chamber.
Use the supplied scraper. Work the flat plate surfaces where the water jacket sits behind the steel — that is where deposits cost the most.
Combustion air ducts — weekly
Clean the air ducts in the combustion chamber with a suitable tool.
These are the passages that deliver the air the fan is metering. Partly blocked ducts mean the controller's fan percentages no longer correspond to the air actually reaching the fire.
Heat exchanger — weekly
Clean the top of the heat exchanger from soot using the brush.
Access is through the service flue gas door (callout 10 on the structure drawing). This is the third pass, where flue gas gives up its last useful heat before the chimney.
Mid-winter
We recommend boiler cleaning in mid-winter at least once a week.
Deposits and gum formation by condensation depend on the fuel type — wood more than coal — the chimney draft and the operation mode. Deep winter combines the longest burns, the lowest return temperatures and the heaviest fuel use, so it fouls fastest.
Tools
| Tool | Use |
|---|---|
| Brush | Heat exchanger and flue passes |
| Scraper | Furnace and loading chamber surfaces |
| Suitable duct tool | Combustion air ducts |
| Ash shovel and metal container | Daily ash removal |
| Vacuum rated for ash | Fine ash, once cold |
Brush and scraper are consumables and are not covered by warranty.
Ash disposal
Ash can retain live embers for days. Store it in a metal container with a lid, on a non-combustible surface, away from the building.
What clean looks like
Clean means bare metal, not "less black." After a weekly clean you should be able to:
- see the grate clearly with no banked ash;
- feel plate metal, not a crust, on the chamber walls;
- see daylight down the air ducts;
- and pull a brush through the heat exchanger without resistance.
If the boiler is not reaching setpoint on a full load of dry wood, the heat exchanger is the first thing to check.
NextChimney careSweeping frequency, condensation, and why the joints fail first.
Maintenance schedule
What a UNI 60 needs daily, weekly, mid-winter and seasonally — ash, heat exchanger, air ducts, chimney and the electrical check, in one table.
Chimney care
Keeping the UNI 60 flue safe and drawing — sweeping frequency, acidic condensation, joint deterioration and what changes the deposition rate.