Carver cascade leaking

[volvoturboman]

Hi all, my van is a 1998 Lunar Solar 505 which we took away for the weekend and as usual heated a tank of water for use. However after heating the tank we noticed the water pump kept coming on and off every couple of minutes. Having just sorted out the pressure adjustment for the water pump I assumed this was the cause and I gave it no real thought and just thought I'd sort it in the morning.

The next morning however my daughter was at the side of the van and notified me that water was escaping out the heater cowling, quite badly too. I screwed the cowling off and discovered it was leaking from what looks like a nut in the centre of the unit. As such I reduced use of the water pump thinking it was only on the outside. However today my wife discovered wet carpet and I traced the wet back under the blanket box to the water heater.

Not knowing a lot about the water heater I'm wondering A. Can it be repaired with a simple seal? and B. Where would I get such seal? What would I be asking for?

 

[Damian]

First things first.
The water coming from what you describe as a nut in the centre outside of the heater is the fusible plug which melts if the temperature exceeds its limit.
As for the leak inside the van it may be one of 3 things.
Either a broken / split inlet or outlet.
They are the plastic connections on the back of the heater on the right, one top (the outlet) and on the bottom (inlet) and are prone to failing on older models, especially the white ones.
If they are black then they have been replaced previously.
The third possibility is a failed tank tie rod which holds the tank to the heater unit, and normally when this fails and water leaks from the tank seal it gets inside the control box under the heater and ruins it.

The best person to contact regarding repairs is Gary at Arc Systems. He is the only person I know who holds pretty much all spares for the Cascade and has been repairing them for years.
Best to phone him on his mobile number and be prepared for a long chat !!!!

 

[ProfJohnL]

The outside leak you describe is symptomatic of the fusible plug.

The secondary internal leak, may just be the water from the fusible plug finding its way inside the caravan, so it may not be the issues Damian has suggested, but never the less it needs to be checked out.

The fusible plug is a safety device, it was designed to remain water tight unless the temperature of the water goes above a dangerous level suggesting the thermostat may have failed. But bearing in mind the age of the heater, we can't rule out simple wear and tear, and the fusible plug can just give up after multiple heating and cooling cycles.

So hopefully it may just need the the fusible plug replacing, but do talk to Gary.

 

[Damian]

Quote "
The secondary internal leak, may just be the water from the fusible plug finding its way inside the caravan "

Sorry to disagree, but it is virtually impossible for this to happen and I have never ever seen it happen on any of the hundreds of Carver Cascade repairs I have done.

 

[Parksy]

Apart from the technical advice that was provided Click Here to contact Arc Systems

 

[volvoturboman]

Guys thanks so much for all your help. I had been hoping the 2 leaks were coming from the same source. Anyway I'll get a proper look tomorrow and trace the leak. I will keep you informed.

 

[ProfJohnL]

Quote "
The secondary internal leak, may just be the water from the fusible plug finding its way inside the caravan "

Sorry to disagree, but it is virtually impossible for this to happen and I have never ever seen it happen on any of the hundreds of Carver Cascade repairs I have done.

Hello Damian.
I to in my time have seen and dealt with many Cascade 1's and 2. and I can tell you I have dealt with Cascade 2's where what I have described has happened.

The fusible plug has overtime has leaked - either due to age or thermostat failure making the water too hot, or even frost damage when the heater was not drained. In any of these cases the water from the tank is discharged into the flue way with the principle idea to extinguish the flame and cause the burner control module to go to lock out.

If the water pump continues to replenish the tank it will continue to discharge water through the fusible plug.

Now my suspicion here is guided by the fact the water pump was not described as running continuously but periodically. This means the water loss was not full bore, but more of a weep. This suggests the Fusible plug has not been blown by excess temperature, its more likely wear and tear

With a relatively small leak the water is likely to track down the fin pack and rear wall of the pack. The flow is unlikely to be enough to extinguish the flame if its being used on gas, and in fact much of the water may well be evaporated if the BCM is burning. And of course if the heater is being used on mains, it will continue to leak as described below with no fault showing on any of the heaters controls.

Water flowing down the back wall of the fin pack will meet the burner control module's seal to the casting. This is not a hard seal, it is sufficient to prevent wafted gasses from the flue passing, but continual water may well soak the seal material and through capillary action find its way to the interior side of seal. This would be made worse if anyone had not correctly tightened the BCM into the appliance casting.

Having described the above, I am not discounting other possible causes of internal leaks, but this is all it may be. and would be a good place to start.

 

[cluker11]

Once when we were away in our previous caravan the Cascade 2 developed a leak at the cylinder seal and it was causing the pump to run almost continuously.

I had to remove power from the pump and drain down the system on site.

We couldn't even use the caravan cold supply.

I fitted a new cylinder seal after arriving home but I also fitted an isolation ball valve in the supply pipe to the water heater so that if a similar occurrence happened I could isolate the Cascade 2 and at least still be able to use the caravan's cold water supply.

I also used a thick black marker pen and wrote on the top of the Cascade's polystyrene cover ' DO NOT LEAN ON HERE '.

Colin

 

[ProfJohnL]

Hello Colin,

It is a sensible precaution to put do not lean on the top of the tank, but if the heater has been installed correctly the tank should be supported by the foot of the insulation jacket.

From experience, I would suggest that a leak from the tanks main 'O'ring is rarely just joint reliving through wear and tear. I did come across one heater where the seal had been displaced, and the pressure relief valve and drain plug had been replaced with a blind brass bolt. On checking with the owner, he had it fitted to a playbus conversion and they were using a mains water pressure or a high powered domestic shower type pump which was capable of delivering 5 to 6 Bar. They had changed the PRV and Drain becasue they were "leaking".

In your case it will almost certainly be the result of one of the following causes:
The tank having been dismantled at some time and not properly reassembled, such as the O ring not being positioned correctly, or the tie rod or the retaining nut not being tightened correctly.

The tank may have been deformed which is usually indicative of frost damage, where the content freezes and the expanding ice is strong enough to jack the tank away from the casting by deforming the central end disk where the tank nut is located.

The tie rod may have failed either by corrosion or being stretched and fractured by the action of frost on the tank.

 

[volvoturboman]

Well I have now removed the fusible plug and it was showing signs of corrosion at the end. Is there any other way to know if this is what it is? I wouldn't want to buy a replacement for it to happen again.

I'm currently trying to isolate the internal leak to see if it is coming from somewhere else. The problem here is all else is dry. The wet patch is to the right hand side of the van just where the side of the seat and wardrobe meet in front of the axle location (Standard 5 berth layout of the time) in front of the gas heater. Nowhere else as of tonight is wet after inspection. My father however (coach builder by trade) who helped me look believes that what could have happened is this. We discovered the wet carpet on Sunday at the camp site, that Saturday night/ early hours Sunday we had very rough weather, a lot of torrential rain and very heavy gusts of wind. The wind was in fact so strong it managed to pull one side of our awning from all its metal pegs and move it about 5 inches along the awning rail (porch awning). So taking this in mind and the location of the wet patch he suggests that perhaps the driving rain was forced down the heater ventilation pipe. Plausible explanation so I'll have to give it time to see. What do you guys reckon about that?

 

[ProfJohnL]

Hello Again,

If there was a continual dribble of water emerging from the water heaters external vent, and from the fin pack rather than the plastic drain plug or over pressure valve both of which are on the left hand side, then that is pretty indicative of a fusible plug failure. However if the casting were leaking in that area you might get the same symptom, but that is virtually unheard of. So the fusible plug is the biggest probability.

If your summation about the water ingress down the space heaters flue pipe is correct then it means you have a problem with the space heater. The heater flue pipe should be continuous back to the heater and sealed to it with a very compliant red silicon rubber "O"ring. This should not leak water. Any water that does get into the heater flue should be ducted away underneath the caravan by a small pipe built into the heater for that purpose. If the flue pipe is not properly sealed you must get the appliance properly serviced for your safety.

Based on your description of the weather conditions, and the fact the wind was strong enough to move the awning, I do wonder if the force of the wind has damaged the awning rail and loosened any of its screws. It may need the rail to be removed fully cleaned and reseated with fresh sealant.

 

[volvoturboman]

on visual inspection the awning rail looks good and no water seems to be leaking on that side. It will be something I will pay attention too. Ive not used the gas for the heater yet. I only required a blast of heat twice and used the electric blow heater. I'll strip it out someday and give it a good examination. I'm having a BBQ point fitted so I'll get the gas man to check it too.

The knob can be lifted straight out the top of the heater so I'm guessing that part of it doesn't even work, could be wrong though.

 

[ProfJohnL]

on visual inspection the awning rail looks good and no water seems to be leaking on that side. It will be something I will pay attention too. Ive not used the gas for the heater yet. I only required a blast of heat twice and used the electric blow heater. I'll strip it out someday and give it a good examination. I'm having a BBQ point fitted so I'll get the gas man to check it too.

The knob can be lifted straight out the top of the heater so I'm guessing that part of it doesn't even work, could be wrong though.

Even on private caravans all work on gas appliance must comply with the prevailing codes of practice and safety checks. This should only be done by a competent fitter.

 

[volvoturboman]

Yep thanks, I'm aware that they do hence why I'm getting a gas specialist to fit the BBQ point.