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Carver Cascade 2 again, water pouring out outside

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Another Carver Cascade 2 query - ours stopped working on gas, but was working on electricity. It was serviced  a few weeks ago, on the day the Great Siberian Freeze arrived, as part of the van's general service. I'm fairly certain it can't have drained properly, as everything froze that day. The engineer properly loosened the big drain plug at the bottom Left of the cowling. He also loosened what I now understand to be the bleeder plug at the top Left of the cowling.

We first used the caravan this week.
Now when even the cold tap is switched on, water pours out through the cowling, apparently through the bleeder plug, possibly other places too, roughly as much water as arrives inside through the tap. The big drain plug is now closed. I can't get the smaller plug at the top to locate in any way, it just twists round, bobbling in and out a bit as it does, but not catching anywhere. I can't tell if water's just bubbling out through that, or more widely.
Is that little plug supposed to shut tight?


We're only just back from the trip, so no time yet to get the engineer to come & look at it & diagnose properly.


But meanwhile, the whole thing is nearly 20 yrs old. I'm wondering whether it's going to be pouring money into a drain to have it mended or even replaced with a reconditioned similar unit from a breaker: it's bound to be a similar age, and may be one of the less reliable ones I've read about after Carver stopped making their own.   Maybe we should bite the bullet & get a replacement modern one by Truma  - or someone else?


The van's too small to upgrade to one with a heater on, there's no space to put one without losing useful space in the caravan, so just a gas/elec water heater seems best.


Comments, and recommendations  would be most welcome to help us in deciding, please.


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What you need to do is remove the outer cover (4 screws) which will give you a view of the main part of the heater.

The top left is the pressure relief valve and the centre bit is spring loaded which needs to be pulled outwards and turned 1/4 turn to open, a further 1/4 turn to close it.

So your description of it "bobbling in and out a bit" is right.

The bottom left is the drain plug which is either tightened or not, it should have an 'O' ring on it which is the seal when it is tightened.

In the very centre, but hidden behind a cowl is the fusible plug, which melts if there is a malfunction and the heater overheats and extinguishes the gas if that is being used as the fuel.


Once you can see the parts, you can run some water into the van and see where it is coming out.

If it is the PRV which may have split, it can be replaced.

Come back with the results of your investigations.


Spares can be got here: https://www. caravanaccessoryshop. co. uk/category/carver-cascade-parts/56

or from a number of other places.

Edited by Brecon
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That's very useful, thanks greatly Brecon.  

I'll hope to find time to do that this weekend, but  whenever,  will come back to you when I have done it.

Thanks again.

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Hmmm - Sod's law applies! It's being inconsistent, like a sulky car which suddenly works perfectly when it approaches the repair garage.


I just tried running water through the system, with the cover off. (as in pic below) I didn't use the Aquaroll, but got through maybe 5 jerricans full of water (recycling it).
Cold tap, fine. Outside leak, nil.

The hot tap, which I didn't mention in my OP, also produced water which was a nice surprise:  the engineer found it wasn't working when he serviced it, and rectified the microswitch, but it didn't work when we were away. Now it works, though I didn't risk powering the Carver unit up to test hot water,  just in case.

I think the water sitting in the floor of the unit in the picture may just be residual, but there was certainly no gushing. When I opened the fast drain plug to empty it again what there was shot out with great force and much air blast.

Maybe I didn't get the heater unit full enough this time to overflow?


I'm thinking that all that sealer round the lower part suggests it's been in and out a couple of times in the past, meanwhile.   When we first bought the van, just over a year ago, there was a high damp reading on the wall round that outlet, but it's dried out very well.


Maybe I should try again tomorrow, see if  the plumbing changes its behaviour?


Cascade 2.JPG

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Thanks for coming back, especially with the picture.

From what I can see your heater is actually in good condition. There are no signs of leaking (no tell tale calcium deposits), and the PRV looks as if it has been changed relatively recently.


It is very probable that the heater has been taken out at some time in the past,  that would not be unusual.

As far as the pressure when you opened the drain plug, that is quite normal and is even more forceful when the heater has heated the water, so stand well to the side !!!!


The heater relies on a gap at the top of the water, to allow for expansion when heating, so you will never fill the tank to the absolute top. .

Edited by Brecon
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That's most reassuring, thanks,  Brecon.

When it's light again tomorrow I'll have another go with both water & with fiddling with the  plug. I couldn't feel that the top one latched onto anything when I turned it round, it just, as I said, bobbled round but seemed to make no difference whichever way it was turned.   Should it press in, or be on a spring, or what? I'm wondering if maybe there's a stalk inside which might snap in the freezing weather when it was serviced?


Incidentally, we were looking over part of those Beacons from which I guess you take your Forum name, while staying at Moorhampton C&MC site this past week. With the snow still on, they looked most impressive.


Best wishes,


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More progress, of a sort. On closer looking just now I realised the PRV plug was split. When I turned it with just my fingers this time, part came away, and there's obviously broken stuff inside too. It looks mottled and brittle with age, for all that it appeared newly changed in yesterday's picture.   (It's brighter and drier weather today, which encourages better looking!)


So I'm guessing that ordering the spare you identified is my way forward, probably a spare drain plug too in case that's about to follow suit.

Is it fairly easy for a moderately handy but truly non-engineering man to fit?




plug split.JPG

plug broken.JPG

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Thanks for the close pic.

Sadly the PRV does look to be in need of replacement.

However, it is not that difficult but more care is needed.

The top part will just unscrew using the first nut you see.

The main part will probably break when you try to undo it, leaving the threaded end still in the heater.

If it does, use a junior hacksaw and cut five slots into the plastic remains (the junior hacksaw will just fit ) BUT only cut the plastic down to the threaded heater.

You will feel when you get to the metal of the heater as the blade will snag rather than the smooth cut through the plastic.

Then use a small flat bladed screwdriver to ease one of the sections you now have cut upwards and outwards.

Once you have the first one out, the rest will follow quite easily.

Clean up the heater thread with  either a tap, if you have one, or a towball bolt .

Put a smear of silicone lubricant on the threaded part of the new PRV and tighten, BUT only tight enough to create a seal with the 'O' ring supplied with the new valve.

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Thank you very much for this truly helpful and concise advice. There's hope for this heater yet!  When the part arrives I'll let you know how things go.


Meanwhile, I have a longer term question while you're here, if that's OK, since you evidently  have  quite some experience of these units.


Our immediate need is that the  plumbing works for a planned trip to France coming up soon, using EHU sites,  but before all this happened, the unit stopped working on gas last year.   Our engineer is reluctant to take it to bits:  it's not a model he deals with these days, and he doesn't want to spend hours on possibly making it worse, with some parts being obsolete. (I found a page online explaining how Truma,  having taken Carver over, deliberately made this happen. ) I'm wondering about the wisdom of trying to sort out the gas side, on our return from France,  so that we could use it when going off grid, or whether ultimately it's going to need a replacement unit, and if so, with what. Any comment would be welcome.


But for now, I look forward to getting it going for this long-awaited French expedition, our first time abroad with a caravan!


Thank you again,


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Hello Richard,

As far as the gas side of the heater is concerned I suspect that the burner module has failed.

I am assuming that when you select gas for the burner that the lights on the control panel go to red after a few seconds?

The lights have the following meanings: Green. ...All OK, Amber. ..Low 12v, Red. .. Burner failure to light.


When you take the front cover off, as you have done, there is another cover held by two cross headed screw bolts.

Remove this and you have access to the burner bar, have a look at the state of it.

It may just need a clean with a blast of air to clear any debris, or it may be rusted away.

With the cover still off, and gas supply on, try the burner again and see what happens, whether it tries to light or nothing.

If nothing, and assuming that the lead to the burner module is actually fitted properly, then it would mean a new burner module.

These are available from Gary at Arc Systems at around the £100 mark.

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Thanks for your patience here :)  I can't remember the light sequence last time I tried it, I think  they were possibly all three coming on at once. .. I'll wait until I have the plug successfully installed (fingers crossed) before filling it up & trying to fire it up.

I had a  l-o-n-g phone conversation with Gary, last year after it failed, and he reckoned it might be a fault in a contact deep inside it, and described, from memory, the exact sequence to get to this to clean it. I tried to write fast enough!   It involved stripping it right down, and breaking off a bit where parts are held together with hot glue. I admit that was more than I'm prepared to bite off, lacking tools or confidence to go that deep.

I am much more likely to have a look at the burner as you recommend. If it's not that, it's presumably likely to be as Gary diagnosed: I gather he's the man who knows most about them.

Our local engineer, who as I said, is reluctant to go inside it himself, presumably in case he ends up getting the liability if the whole thing fails, now suggests maybe sending  the whole unit back to Gary anyway.

I'm inclined to try the valve replacement myself first, then at least we could hopefully have EHU powered hot water. Since we leave in only a few weeks, I'm wondering if there would be time for Gary to repair it before we head off - do you have experience of how quick his turn-round time is?

I'll post back on what success I have with the valve & the burner when I get to them.


Again my thanks and good  wishes - this is how caravan forums are at their best!

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Update: the valve plug's out, after much persuasion.   Maybe I was too wary of cutting right down, and damaging threads, but it took a lot of work with screwdriver and trusty old scout knife as well as junior hacksaw blade!

I don't have a tap, nor a suitable bolt available, so haven't cleaned it with that. It's had a cloth on the end of some sticks waggled round firmly in it to get the gunge out, and looks as shown.

The new valve is at present unwilling to quite fit beyond the first thread or two with finger pressure. I'm not forcing it with anything tougher, so for now there it rests
But I feel there's hope.

. ..



. .. or at least did, until our engineer phoned just now  as I wrote this, to offer words of doom, saying that in cleaning it from the outside, the chances are I've got bits of plastic inside the tank, which will later re-emerge and mess up the valve anyway. Hmmm. Not so good.

Valve plug socket.JPG

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You have done well, so far.

You can use a spanner on the valve, just gently move it backwards and forwards, it will take quite a lot of pressure before it does any damage, or pop down to your local hardware shop or Halfords and get a bolt.

As far as bits in the tank, did you see any big bits drop in as you were getting the old bits out?

What you can do is back flush the tank while you have the valve out.

Remove the drain plug and put a hose in the top and flush the tank.

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Here's today's update. This morning I phoned the superbly helpful Gary, who reassured me there was no reason why I shouldn't go ahead, proceeding as you've advised. He identified that since you mentioned the bolt, you'd obviously learned from him! He also advised cutting a couple of V's in the end, in order to make it into more of a tap. So I did. And I put water in the tank & drained it too. He was saying I could also drain it through by taking off the outlet pipe on the inside of the van, but I confess I chickened out of that.

So now the valve's in place, and seems to be holding nicely. It's as tight as I can get it with fingers, which was just enough to get rid of a needle fine jet of water escaping round the seal. I might use a little gentle extra pressure on it. Whether or not it works on electrics, which I've not yet tried, if it goes on behaving, we can at least use the cold water plumbing without losing it all over the field, then hopefully get the whole works overhauled by Gary on our return from France.


So thank you again, very much. We were looking as if we'd end up having to work entirely off bottled water for our trip!


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Well done.

If I were you I would just tighten the valve by one flat as when the water is heated it will create pressure in the tank, which may be enough to get past the seal you have at present.

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I'll do that.    I was thinking that indeed the extra pressure might well  force its way by.

I found that the leg winder, which also has a wheel-nut socket at its other end, just fitted nicely when it came to removing the old valve. Its length,  however,  means that rather than destroying my neighbours' nice new white car I'll just wait until they're out. :)


The next issue is that for some reason the  hot tap on the kitchen sink appears to have a variable microswitch fault, which is frustrating, so sometimes it chooses to work, sometimes just fails to respond. The engineer thought he'd rectified this in the service, but it's still inconsistent.
But at least it seems we can now use the cold system without irrigating the area round us, which we couldn't before,  and that's the important bit for now.

One step at a time!


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Just a quick rider to that - I realise the winder handle fitted well when removing the remains of the valve, once I'd removed the spring loaded outer section. On the new one, the outer bit, of course, doesn't line up with the part screwed into the socket, so using the handle is going to just tighten up the outer part. Would I damage anything if I took the outer part off in order to tighten the inner part, I wonder? (It'll probably have to wait until tomorrow, anyway, I'm off out all day today).

Thank you again,


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9 hours ago, Brecon said:

Whatever you do, do NOT use the winder handle !!! :o

I hear and obey!

On thinking about it I can see various reasons why not. Maybe I'll just wait for a warmer day to exert more finger pressure? While I could get whatever one calls a tubular type spanner thing, (note use of techie jargon here),  but there would still be the problem of the inner & outer parts not aligning conveniently to fit it.

Have a good Easter weekend, meanwhile. I'll not be seeing that warmer weather yet, I'm thinking.

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I've not found one in my collection yet - have to make an investment! The only one which  would fit had too much round the end to actually get into the space in the corner of the heater.

Thanks again,


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