For full (from scratch) and partial (boiler only) diesel fired central heating installations carried out. I’m NOT tied to a particular brand and I will (and do) fit whatever a customer specifies. I recommend Webasto Thermotop because in my experience they are the best heater available at the moment.

  • They’re quiet.
  • Reliable: Main components – ECU, airmotor, waterpump and fuel pump are very well made. There are no specific weaknesses unlike with the other comparable heater systems that I work on.
  • Easy to service with a simple one piece stainless steel burner which you can get inside.
  • Good dealer network.
  • Most popular diesel heater unit fitted to narrowboats in the UK. This means most fitters/engineers are used to working on them.
  • 36 month warranty (which I’ve never needed to use).

When a Webasto heater fails prematurely it’s generally because it’s been installed incorrectly. For a Webasto to perform efficiently and be reliable long term it’s most important the fuel supply and central heating circuit inside the boat are installed to Webasto’s specifications. These are points and basic standards which you might assume every Webasto fitter installs to. Many engineers, boatyards and even main dealers don’t install to these fundamental standards.

Above the basic requirements my installs are always neat and tidy and well thought out. The standard wiring loom is shortened, clipped and supported properly. Exhaust systems are supported and installed neatly and where necessary extra lagging is used – the lagging sock supplied by Webasto are not great. Fuel pipe is properly fixed and supported. I pay great attention to refinement and add extra features so the heater runs quietly. Sometimes the heater can be mounted on a welded steel upstand on the swim. This is a neat way to install, keeps fuel pipe lengths short, and helps maximise refinement inside the cabin.

If there’s any doubts about the existing fuel supply I fit a new dedicated supply which is as per the spec recommended by Webasto and draws from 5-6 inches off the bottom of the tank to limit the affects of a diesel bug and water contamination.


Using the wrong type and mixing antifreeze can lead to serious problems with all diesel boilers and central heating systems.

  • I don’t recommend using any additives and only use good quality antifreeze.
  • If you are going to add different types/brands of antifreeze make sure they are compatable. Mixing different types of antifreeze can create serious corrosion and scaling issues causing boiler heat exchangers and coils in the calorifier to become inefficient (requiring replacement).
  • If there’s any doubt about the age or condition of coolant in the system then it should be drained and refilled.
  • If the coolant is an opaque brown colour (caused by mixing 2 & 5 year antifreeze) or there’s significant scale/rust suspended in it then it should be flushed too.
  • Using the correct ratio of antifreeze is particularly important with the Webasto Thermo Top C.