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Central Heating Boilers

COMBI Boilers

In static holiday caravans and residential park homes, combi boilers for central heating are commonly fitted. The main manufacturers are MORCO, for which we are warranty agents here at Stephen Ward Caravan & Boats, and Worcester Bosch, Ariston, and others are also represented. However, we can repair most caravan boilers.

The two types of boilers are normal combustion for older models and the new forced-air combustion, which combines a condensing system. All rooms are room-sealed, taking air directly from outside and releasing fumes to the outside via the same flue system.

Boiler lighting sequences in all models are the same:

  • Demand either opens a hot tap or turns the thermostat up.​
  • Fan comes on.
  • The air pressure switch recognises that the fan is running.
  • Computer starts ignition sequence, i.e., sparks.
  • Gas then flows to the burner.
  • Gas is lit.
  • Computer senses gas is lit via a sensor.
  • Boiler runs until demand is stopped.

Any breakdown in this sequence can stop your boiler from working, and multiple sensors within the boiler can also be at fault.

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Regular inspections of your appliances can help prevent breakdowns. 

Radiators are filled with a mixture of antifreeze and inhibitor, which prevent rust and black sludge build-up, which can stop the boiler from heating properly. This inhibitor needs to be topped up every 5 years.

AS FROM APRIL 2014 all newly commissioned condensing room-sealed combi boilers must have a reading from a flue gas analyser.

Touring Caravan Boilers

There are two types: one is just a normal water heater (Truma, Propex, Whale, and the older Carver). Then there are combi units: Truma blown-air heating and hot water, and Alde radiator heating and hot water.

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The modern caravan is normally powered by either gas or mains 230v electric. They require the hot water to be heated for about 20 minutes before it is needed. You can use both gas and electric heating sources to heat the water up quicker if required. Since the water is in a sealed tank, I recommend not leaving the water heating switched on when not in use. The common problem is limescale buildup from prolonged heating without a water change. This will then cause two issues: overheating, which will cut out after one heating session or the electric trips will activate.

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On Truma water heaters and combi boilers, the heating elements can be repaired, but this requires removing the heater.

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On combi boilers, the combustion fan and sensors are common issues; they have to be removed and can be sent to a specialist for repair or replacement.

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