All I can find read and it might be of some help.
The weather could well have something to do with it, damp will have this effect. What is happening is the electronic flame sensor is not reconising the flame has lit and shutting down as though it hadn't lit. Depends just how water hits the flue cowl but it is quite possible for water to get from here all the way inside the black box which is under the heater and inside the van.
Solution I hope is to remove the 'burner module' open up the attached black box and dry it out, removing any corrosion that has already occured with a brass brush. Leaving it more than a few days can be to late. It could also be build up of water in the burner itself but this should have drained away quite quickly and not cause lasting harm.
After turning the gas off, removal is from outside behind the outer plastic flue cowl and an inner aluminumn plate. Behind these in the bottom righthand corner are two 'cross head' screws, undue these and the module slides out. Any resistance means the box lid inside has sprung open and will need to be squeesed shut from inside to get it started though the hole, the electrical connection can then be pulled free. Remember the two screws are also holding the gas joint so care should be taken when replacing, also ensure when refitted, the black foam seal and bracket at the back of burner is as high as possible and parallel to the top of the recess in which it fits.
The Carver Cascade 2 is a 9 litre storage water heater, which when running on gas will heat the water to 65deg c in about 45 minutes. On 240V mains assuming it has this facility, the time can be somewhat longer or shorter depending on the wattage (660w 3amp to 970w 5amp) of the element fitted, you can use both gas and electric together for faster times.
To operate the gas there is a wall switch with three lights, green amber and red. When switched on the green lights, (water tank must be full, i.e. water coming from hot taps), if it stays on after about 8 seconds then the gas has lit and all is well. If the green is joined by the red then you may have a problem, but if the gas bottle has just been changed then air in the pipes will have to be bled through by repeating the above 2 or 3 times. Once lit, and it should light without any pops and bangs, (this would indicate it needs a service), the heater looks after itself and gives constant hot water. Any problems will cause it to shut down safely and show the red light, indicating a fault. Forget the amber light, it’s to show low voltage and won’t light unless the voltage is so low the heater and everything else packed up long since, though you may notice it ‘flash’ as the switch is turned on or off.
The 240v emersion heater if fitted is totally separate, and lies behind a white plastic box on the inboard end of the water tank. It is controlled by a switch, often close by and at floor level, but sometimes as part of a remote control panel. The switch has a red light to show it’s “on”, not that it’s working, this will be determined by the water getting hot. If it does not then it may have “tripped” Two types exist, early circa 1990 are non-re-settable, but are repairable. Later models have a Red button on the end of the plastic box, sometimes behind a flap. Switch off mains, and press to reset.
Other faults concerning the gas side very often come down to the “Burner Module”. This handy little unit contains the burner, gas valve and all the electronics which control it, and is accessible from behind the cover outside of the van. In the event things go wrong it’s a 5 minute job to replace it, either with a new or serviced exchange unit. One other safety device is a wax filled plug, this again is behind the outer cover and shows itself as a 13 mm nut set in the fins above the burner. The wax will melt if things get too hot allowing hot water from the tank to spray over the burner putting the flame out, this will render things safe, but will probably require a new module because it’s control circuitry will be faulty,. A point to note here is that over time the wax degrades or the threads leak, allowing water to seep onto the burner causing it to rust prematurely, eventually this will require replacement of the whole burner module.
That in a nut shell as they say, is all there is to it.
bob
September 2012
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