Carver rapide problem

[treforissa]

Hi all, I need a bit of advice and reassurance please. Just acquired a Motorhome fitted with a 1997 Carver Cascade Rapide 9 litre water heater. When I came to check the water pump I found it wasn't working so bought a new one. The old one was marked as 16psi, the new one is 20 psi as I coulkdn't get hold of a 16psi model. I proceeded to turn the pump on and it immediately primed and so I opened a cold water tap, got water. However, I noticed that the pump was still running when I turned off the cold water. As I crossed the floor there was a big bang and the Carver tank blew off!! I have read that the central bar corrodes and this was the case which could be seen by the amount of 'clean' alloy showing in the centre of the bar. I have repaired the problem, but, could someone answer the following questions please.
1/ Is the tank built to hold a constant 20 psi?
2/ Is there any procedure I have to follow on recommissioning the heater?
3/ Am I correct in assuming that the water in the heater, when full, is kept at the 20psi pressure which is only released when the hot water tap is opened?
Sorry if these questions are repeats but I am very nervous of recommissioning the heater.

 

[ProfJohnL]

Hi all, I need a bit of advice and reassurance please. Just acquired a Motorhome fitted with a 1997 Carver Cascade Rapide 9 litre water heater. When I came to check the water pump I found it wasn't working so bought a new one. The old one was marked as 16psi, the new one is 20 psi as I coulkdn't get hold of a 16psi model. I proceeded to turn the pump on and it immediately primed and so I opened a cold water tap, got water. However, I noticed that the pump was still running when I turned off the cold water. As I crossed the floor there was a big bang and the Carver tank blew off!! I have read that the central bar corrodes and this was the case which could be seen by the amount of 'clean' alloy showing in the centre of the bar. I have repaired the problem, but, could someone answer the following questions please.
1/ Is the tank built to hold a constant 20 psi?
2/ Is there any procedure I have to follow on recommissioning the heater?
3/ Am I correct in assuming that the water in the heater, when full, is kept at the 20psi pressure which is only released when the hot water tap is opened?
Sorry if these questions are repeats but I am very nervous of recommissioning the heater.

Hello treforissa,
The Carver Cascade Rapide was specified to be able to handle a working pressure of 2.5Bar See
http://arcsystems.biz/manuals/Cascade2.PDF

This needs a little explanation, When the tank is filled with cold water, and the taps closed which effectively seals the heater, as it heats up the water expands into the heaters air cap. as the water expands in most cases that means the internal pressure will increase. To allow for this, the normal maximum pump pressure should be no more than 1.5Bar (22psi) which gives a sensible margin of safety. Consequently your new pump should be perfectly acceptable.

In terms of recommissioning, there are three main points of concern. Obviously the the tank needs to be checked for its seal to the main casting and to all other ports such as the electric element. so it will be water tight. But with a 1997 heater its highly likely the plastic fittings will have become rather brittle, It would be wise that if the heater is on the bench for the tank, it would be sensible change them all and the fusible plug in the fin pack

The gas system should checked, in particular as the tank has dumped its water through the big seal, it will have drenched the burner control module. If the BCN needs to be replaced, you may need to change the associated control switch also, as the wiring system did change over the life of the product.

The mains element should be ok but again it would be sensible to check its Live to earth insulation resistance.

If you are unsure about any of this or the refitting and gas safety testing you would be wise to seek professional help.