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Carver Water Heater


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just arrived back from our first trip away this year. The water heater is only heating with the gas and appears not to be heating with the electric. Also i think we have a air lock in the pipe as the pressure starts off ok then dribbles to nothing. Does anybody have any ideas how to cure this. is there a bleeding valve on the carver system for this. the system was drained before winter.

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Quick answer is check the fuse and/or check the override switch which is a red button mounted on the side of the heater unit.


Has the van been serviced as this should have been checked.


If the presure problem is the same with hot or cold, I would guess that the system is a pressurised one and that the presure switch needs adjusting. If this is the case, it will be a housed in a plastic unit mounted near the water inlet and will either be a knurled nob or a screw type with a locking nut (also in plastic).


If these hints do not help, please supply more details like the make and model of the van and as much information/description of the Carver unit as possible. I am sure Gary will then be able to provide a more detailed soultion.





Swift Challenger and Kia Sorento XS Auto

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Most of this I have said before but I have added a bit about frost damage.


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 “onâ€, 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 Moduleâ€. 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.

A problem that can arise in spring is the discovery of frost damage to the water tank, the non-return valve which is part of the cold water inlet and other plastic fittings. Failing to drain the heater when there is a chance of temperatures dropping below freezing can be very expensive to repair and should be avoided by removing the drain bung and allowing the heater to drain completely. Later models have a valve above the drain hole in the top left corner of the flue cowl, these have a ‘toggle’ showing that when turned a ¼ in any direction will allow air into the tank and assist the draining. Older models still have the valve but the flue cowl needs to be removed and the valve end pulled to open it, in this case opening all taps in the van will do much the same thing. It is most important that the drain bung is then only placed back into the hole and not screwed in, any water left in the system can then drain away.

Frost damage to the tank will be obvious by the leaking water from the damaged seal, the damaged non-return valve quite often will prevent water coming from the hot taps although the cold water flow will be fine. Other fittings are often cracked by the pressure of the frozen water and will leak on refilling the system.



Arc Systems are specialist Carver caravan product repairers, committed to providing a comprehensive service as well as spare parts for these popular heaters.

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