Carver Cascade problems

I understand the electric and gas parts of the Carver Cascade water heater are completely separate - however I have problems with both of them  

I have a 2000 Peugeot Symbol, just got it a week ago. Annoyingly the water heater was the one part I didn't check before buying, though the seller told me everything was working. I may get back to her if any repair is costly......

When I hook up to the mains, I switch on the master switch, and the two MCBs.

In the cupboard are 2 switches with lights on them, one marked battery charger and one marked water heater. The battery charger one is fine, but if I switch on the water heater the main trip switch immediately goes. Not sure what I can even look at to diagnose this further. The overheat button on the end of the heater isn't popped out.

On the gas side, when I switch it on the green light comes on immediately and 10 seconds later the red light comes on. Have tried loads of times, it always does the same. There is definitely gas, the valves are all open, battery is fine.

Any suggestions for either or both problem?

Scott.

Have you a cowl on the outside covering the flue, if so this may need removing. this is a problem we have just come across when using gas to heat the water. On hook up no problems.

No, no cowl, just the flue plate held on with 4 screws.

Electric problem: It sounds to me (and only my opinion), like either the element in the Cascade has failed, or there's a short circuit in the supply to the element, live to earth or live to neutral.

Gas problem: Can you hear a popping sound when trying to start the gas heater? If so it may be the burner. Here's a picture of ours when we had the same symptoms recently.

The gas was escaping from the rotten ends of the burner and building up in the combustion chamber.

I bought a new burner to replace it and fitted it myself, but you should only attempt this if you are competent and confident.

Hi  

scott4534 wrote:but if I switch on the water heater the main trip switch immediately goes

meanchris wrote:Electric problem: It sounds to me (and only my opinion), like either the element in the Cascade has failed, or there's a short circuit in the supply to the element, live to earth or live to neutral.

I’d agree with that.

By “main trip switch” I assume you mean the RCD (the trip with a test button). If so it will be caused by current leaking to earth.

By far the most likely cause is a fault in the heating element, probably a hole in the outer casing letting water into the element.

Thats assuming it's nothing daft like a spiders web inside the switch (it's been known. ) 

Brod.

meanchris wrote:Electric problem: It sounds to me (and only my opinion), like either the element in the Cascade has failed, or there's a short circuit in the supply to the element, live to earth or live to neutral.

Ok thanks. Dealing with one thing at a time then - how would I check the electric element?

scott4534 wrote:Dealing with one thing at a time then - how would I check the electric element?

It's not too easy to check this with a normal meter, as typically the resistance is too high for a conventional meter to register if the element is holed. You may be able to spot it by visual inspection, though I had one fail (in a domestic immersion heater) which showed no signs externally that I could spot (but it was fairly corroded all over).

However, if your RCD trips as soon as you turn on the electric part of the water heater and you have confirmed that there is no water leaking onto the external mains connections and no physical damage (e.g. trapped wires) then you can be pretty sure it's the element.

-mojo- wrote:

scott4534 wrote:Dealing with one thing at a time then - how would I check the electric element?

It's not too easy to check this with a normal meter, as typically the resistance is too high for a conventional meter to register if the element is holed. You may be able to spot it by visual inspection, though I had one fail (in a domestic immersion heater) which showed no signs externally that I could spot (but it was fairly corroded all over).

Sorry you're 2 steps ahead of me.

Where is the element and how would I get access to it? I think it's under the bench seat at the opposite end of the module with the gas flue, but can someone confirm? There's a wooden housing there with a peep-hole access panel to the reset button.

I'm competent with DIY but need to know where to start 

Yes that's where the element is but, as -mojo- says, you really need an insulation tester (megger stylie) to confirm that the element is faulty.

If you're lucky (depending on how you look at it  ) the element will read short circuit, once disconnected, from the connections to its casing with an ordinary ohm meter and you can just get a new one.

If you're going to investigate this yourself, PLEASE don't rely on chance when disconnecting/testing/replacing the element. Make sure that the EHU is DISCONNECTED from the supply, not just switched off at the circuit breaker.

Removal of the heater is from outside. See this factsheet for details.....

[You must be registered and logged in to see this link.]

I had the same problem as in the photo sent by Meanchris, I fabricated a  new end to the burner and re fittted still working well 12 months on
mike
vwt4

vwt4 wrote:I had the same problem as in the photo sent by Meanchris, I fabricated a  new end to the burner and re fittted still working well 12 months on
mike
vwt4

Respect 

Hi  Scott.
This may or may not be of help.
We had a water leak problem with the Carver Cascade fitted to our Duetto which at the time we didn't know about this forum so I was very unsure what to do.
After removing the whole unit from the Duetto and purchasing a new part from a guy called Gary at Arc Systems managed to fix it and is working ok.
If you worried about trying to fix the problem yourself but can remove the whole unit,Gary,assuming he is still trading, is also a gold mine of information and can
fix Carvers at a cost.
Gary was at 13 Far Street,Bradnore,Nottingham NG11 6PF on 079010544431 or 01159213175 and I hope he still is.

Tony

Hi Scott,

I also have a 2000  Symbol so the chances are the Carver Cascade is identical to yours. I have also had several problems with this water heater, all of which I have fixed myself. Please note I am not an expert - just a retired engineer and reasonably competent DIYer. So, in no particular order,

1 - the link Paul posted showing how to get the heater out is excellent. That is what I used.
2 - the heater on gas needs a very good "12volts". Mine would only "stay green" and go through the start-up cycle if I was on mains hook-up with the battery charger switched on, otherwise the light would go red and the burner wouldn't light. Turned out the leisure battery, although OK for most things, had one faulty cell which was reducing the overall voltage enough to stop the heater starting up. I now have a new leisure battery which has a good enough voltage to start the heater on gas without the battery charger hooked up.
3 - My gas burner was also burnt out at the end farthest from the gas supply, just like Mike (VWT4)'s. This will probably also stop the "start" cycle completing because there is insufficient flame on the heat sensor to feed back to the electronic control (this is like an automated version of having to keep the gas ring knob pressed in on the cooker for a few seconds when lighting the ring). Quite independently I did the same as MikeVWT4 and made up a new burner end and brazed it on. Works fine now and has done for several months.
4 - I suggest you take the heater out completely and check your burner. Also with it out and disconnected from the 240v you can measure ohms across the 240v element. The element is 830w and quoted as 3.65amps. So the resistance R is V/I = 230/3.65 = 63 Ohms (may not be exact due to inductive effect, but something around this figure would suggest the element is OK. I suspect that if your heater is tripping the breaker you will get a dead short. However, it's possibly in the wiring, so by removing the heater you can isolate the fault.
5- the other problem I had was a water leak, which was causing the pump to pulse on and off even with no tap open. This turned out to be a leak where the heater can is bolted to the heat exchanger with a large diameter "O" ring seal. I fixed this by hooking up the heater to a mains water supply (about 3 bar pressure in my case) with the heater out and on a bench. I carefully tightened the bolt until it stopped leaking. It has been fine for several months since this.
6 - Although I actually didn't need any replacement parts for my fixes, there is still a reasonably good supply of parts for these heaters on ebay including new 240v elements, "O" rings, burners and also the wall mounted control boxes. I understand Carver was taken over by Truma sometime after our vans were built (around 2003 I think) and Truma did not continue with this heater in its exact form. Truma make a replacement but I don't think the parts are interchangeable. Hope that helps.

Good luck and rgds

Mikebro 

Hi  

mikebro wrote:
Also with it out and disconnected from the 240v you can measure ohms across the 240v element. The element is 830w and quoted as 3.65amps. So the resistance R is V/I = 230/3.65 = 63 Ohms (may not be exact due to inductive effect, but something around this figure would suggest the element is OK.

Ahh but:

That would be true if it was the over current trip that was operating but from the description it sounds to me that it’s the RCD. If this is the case the current is flowing from the 240V supply to earth and may be as low as 30mA. Since that would be because of an insulation breakdown it may only occur when 240V is applied and so may not be measurable by a  “standard”  type meter hence earlier suggestions that an insulation tester could be required.

So it is possible for the element to read the correct resistance and still be faulty.

Brod.

Brod,

You may be correct.

Rgds

Mikebro