Truma water heater advice

[Guest Derek Uzzell]

In a posting of 26/01/2006 'Chas' asked whether the cowl-cap on the external flue-vent of his motorhome's Truma Ultrastore gas/230V water heater could be left in place when the appliance was being operated solely on mains electricity. I replied that the cowl-cap could be safely left in place when the heater was being run on 230V only. This is correct. However, I also suggested that, unless the heater was never to be run on gas, it would be sensible to leave the cowl-cap off "except for any long periods when your motorhome is not being used or when you are employing a hose to clean it". This was BAD advice! During a visit to the Truma NEC stand to check if a cowl-cap was available for Combi flues (apparently not anymore) I mentioned that Ultrastore cowl-caps rarely seemed to be used by motorcaravanners and asked how important they were. Examining a cut-away Ultrastore revealed that (unlike the Combi) insects, rainwater, road muck and general debris can quite easily enter an Ultrastore's gas-burner chamber when the external flue-vent is unprotected by the cowl-cap. This can seriously affect operating efficiency and, at worst, cause the heater to malfunction. Such 'cowl-cap not fitted' faults were said to be commonplace (and excluded from Truma's Ultrastore warranty terms incidentally.) I asked what would happen should an Ultrastore cowl-cap be inadvertently left in place when the heater was fired-up on gas. I was told that the heater should shut itself down before any harm resulted to the cowl-cap or to the appliance itself. (Comforting to know but, if I had an Ultrastore, I'd be a mite reluctant to test out that theory!) Anyway, advice from the Truma technicians is that an Ultrastore's cowl-cap should ALWAYS be fitted except when the water heater is being operated on gas. (This clarifies the advice given in the Ultrastore Operating Instructions leaflet.)

[Guest Bill Ord]

When I had an Autotrail Cheyenne 635 fitted with a Truma Ultrastore water heater it was impossible to light the water heater if I accidentally left the cowl-cap in place. An alarm light would come on on the panel to indicate the fault and on removing the cowl all would be well, I never had any indication of the heater trying to start and it never started with the cover in place. I always observed Tuma's advice on leaving the cover in place when travelling and never had any problems in fours years use and the van was used 90% of the time on gas as I rarely use hook-ups. Bill Ord