What is a boiler service?

There’s no clear and simple definition of what constitutes a boiler service – why else would I open up boilers that have been “serviced” regularly to find them in need of a good clean?

Rather than me writing a lot here, I’ll defer to Mike the Boilerman’s wise words on the subject of boiler servicing: http://www.miketheboilerman.com/servicing.htm

I’ll tell you in outline what I do, and why I often take so long:

  • Visually check the flue as far as possible to make sure it’s clear and intact and in a suitable location.
  • Check that ventilation and case clearances are adequate.
  • Test the property’s gas supply for tightness and pressure: if the gas pressure to the boiler isn’t correct, it may be prevented from working properly. (This test can open a can of worms by revealing gas leaks or requiring the gas emergency service to rectify the pressure.)
  • Follow the service instructions in the manufacturer’s Installation & Service manual, which I always try to have on site, often in electronic form. If the manual says open up and clean, that’s what I do. If it says take a flue gas reading and open and clean or not, depending on the readings, that’s what I do, and so on. There’s now a wide variety of boiler designs and service approaches, much greater diversity than in the past. There’s no one-size-fits-all method, and the manufacturer should know best what needs to be done.
  • Where appropriate, check, and if need be, re-charge the expansion vessel with air.
  • Check the boiler’s flame failure detection behaves safely and correctly when the gas supply is shut off.
  • Make final measurements including the rate at which it burns gas, and always, a flue gas analysis. I record these measurements as they form a useful reference for the next service.

I’m a big fan of electronic “flue gas” or “combustion gas” analysers but I think they’ve come to be over-relied on, and used as a means of cutting corners, like avoiding a boiler clean.

A suggestion for those with annual “service contracts”- take a look and see whether what’s promised is a service or an “annual safety check”.