Carver Cascade water heater problem

[Guest Brian Ramsden]

I have just refilled the water tank on my A/S Talisman, after draining it down for the winter, and I can only get a trickle of water out of the hot tap. The cold works fine. When I turn on the hot tap (it is the same, whichever tap I try) at first water comes out as normal but the pump does not immediately cut in and the pressure drops to almost a trickle, then the pump cuts in and it comes out at normal pressure, then almost immediately the pump cuts out again and the pressure drops - and so it goes on. I have checked that the drain plugs outside are not leaking, and that water comes out of both of them when they are released. I have tried putting on the water-heater. This works, giving me a trickle of hot water. I have tried gently prodding the valve inside the drain outlet and, when prodded, this causes water to gush out. Anyone any ideas? Themanual mentions a pressure release valve which opens to relieve overpressure, but it does not say where this is, so could this be failing to close properly? the heater is a Carver Cascade euro Rapide GE.

[Guest Derek Uzzell]

Your Talisman must have several hot taps - do they all perform in the way you describe? If so, I'd expect something wrong between pump and heater or with the heater itself. If it's just one hot tap playing up, then the fault is likely to lie between heater and tap. As older Talisman vehicles (you don't say how old yours is) had 'caravan-style' water hoses, it's possible that one of the hot-water hoses has kinked badly, of deteriorated internally, causing a partial blockage inside.

[Guest Brian Ramsden]

Thanks, Derek. It is the same whichever tap I try. The hoses were all replaced with thick walled plastic in 1999. although the 'van was built in 1996.

[Guest pete walker]

just a thought brian, is the pressure valve the one above the drain pump or have you got another in mind? pete

[Guest Brian Ramsden]

Having talked to an expert, it sounds as if the pressure release valve is the same as the one on the inlet to the heater, which works both as a non-return valve to stop water being sucked from the heater when running cold water, and as an over-pressure valve. Apparently they tend to stick, especially if damaged by frost. I may be able to release it by taking out the heater, disconnecting the inlet pipe and gently pushing the valve open. However, they only cost £5.60 to replace, so that is what I will do. Unfortunately you can not get at the inlet pipe connection from inside, so far as I can see.