Calorifier to leak or not to leak......

[Dibbo]

Hi Folks, here's an oddity you might be able to help me with.... a yr or so ago, we turned on the immersion heater only for the fuse to trip, lifting the bed found the area around the immersion heater full of water, ( horizontal tank with heater on the top), but not running down the sides, just full. So we dried it out, and cut some of the insulation away looking for a crack, no sign, so made sure very dry, left it a day or so checked agian, full of water, but not enough to wet the electrics, ( bigger space with less insulation maybe), this went on for a couple of days then stopped, no more leaking, even though we cant find the split, or leak. Immersion fuse was put back and all has been well since, ..... untill today, We put the immersion on last night for a nice hot shower ( we get two good ones from a tank) , the ife's was hot then wartm, mine was hot/warm/ chilled,odd We thought, inspection this morning showed water again gathering in the well around the immersion heater, So think possibly either the immersion wasnt on long enough, doubtfull as genny ran long enough, ( fuse hasnt trpped either) or not working at all if it's possible that the Vetus built in Genny also heats the water ( not sure on that)

If the tank is split, why doesnt it fill the bed space with wate, and why is it an intermittent fault?........

Your thoughts folks always appreciated......

 

Dibbo

[Paul C]

Two questions:

 

- Is the immersion heater element fitted properly, I'm thinking possibly the leak is in the thread to mount it

- What kind of pressure relief does the calorifier have, and does it work properly (a pressure gauge in the system is very useful here!)

PS I suppose its 3 questions really.

[Dibbo]

I know we thought about the thread to the immersion heater, but we did rule that out at the time, cant remember how we came to that conclusion but we did, I wonder why intermittent, unless the pressure relief is having a paddy from time to time, daft question, is this fitted close to the tank, or else where in the system?

[Paul C]

I can't answer for your boat. On my boat, its fitted a long way away from the calorifier. Its in the hot water line, somewhere. Since the water pump is located under the sink unit in the bathroom, and there's also hot water pipework there (for the sink unit....) then its here, to keep all the items you might want to look at every so often, in one handy place. From the PRV runs a short pipe to the shower sump (we have an automatic shower pump), thus although our system loses a little water each time it heats up and cools down, this water is well controlled and doesn't enter the cabin bilge area or engine bilge area.

 

Other boats may have a PRV fitted very near the calorifier, and an outlet in/near the engine area.

 

Other boats may have an expansion tank (similar to a header tank on the cooling system) or a pressure vessel similar to an accumulator, so that the water which is wasted with a fixed volume PRV system is retained and returned to the hot water system. These (I believe) will still have some kind of pressure relief too, for example there may be a PRV somewhere in the system too, or the expansion tank has a pressure cap.

 

Basically you'll need to look at your pipework and find out what kind of pressure relief your hot water system has.

PS Once you find the pressure relief valve, give the knob on the end a couple of turns. What this does is manually lifts the valve and any crud which can build up and cause issues, is self-cleaned off (more or less). PRVs do fail though. Ours failed but the other way, it let water out on low pressure. So I replaced it with one with a pressure gauge on it for very little money (£10.49)

[Guest]

I have replaced elements in houses were the water was finding its way through the actual element under the cap. The thermostat tube coorodes over the years and can leak. This might explain why the breaker tripped out?

[Tony Brooks]

The only way I can see water getting to the inside of the immersion heater is a leak within the heater itself. Either in the tube that the thermostat sits in or where that tube plus the element tube is sealed to the boss. The boss usually stands proud so I can not see how an water on the calorifier or leaking from the thread can get into the centre unless the boss is not horizontal, even then I find it hard to believe water would get in.

[andy3196]

When mine has done the same, it turned out to be that the immersion heater had worked itself loose, no a huge amount, just a fraction of a turn was needed to tighten it up.

not that surprising really with the amount of vibration it's subjected to.

[ditchcrawler]

I have replaced elements in houses were the water was finding its way through the actual element under the cap. The thermostat tube coorodes over the years and can leak. This might explain why the breaker tripped out?

That is what I was going to say, I have found that more than once when going to an IH failure

[Grace and Favour]

Dibbo,

 

It may well be that your PRV is not releasing the increased pressure when you're heating your water - - have you considered fitting an expansion tank into the hot system?

[Guest]

Dibbo,

 

It may well be that your PRV is not releasing the increased pressure when you're heating your water - - have you considered fitting an expansion tank into the hot system?

Good point, I fitted one a few years back and it is a much better solution. I initially made the mistake of getting one for a heating system and it went rusty inside, but I got a potable one off Ebay that can withstand 99degC. I used to hate relying on the PRV, and understand that fitting an expansion tank is kinder to the calorifier?

When mine has done the same, it turned out to be that the immersion heater had worked itself loose, no a huge amount, just a fraction of a turn was needed to tighten it up.

not that surprising really with the amount of vibration it's subjected to.

I used to hate immersion heater jobs, cause I could never get the swines to undo! Never changed one in a boat yet, but can see that vibration might loosen them. I tried to undo one in a house once that had been "stagged" in and the top of the copper cylinder ripped. After that I never forced them, and on one occasion left the dead one in, and got a plumber to put a new flange in so I could fit a new element. Sorry I am drifting again....

[ditchcrawler]

Good point, I fitted one a few years back and it is a much better solution. I initially made the mistake of getting one for a heating system and it went rusty inside, but I got a potable one off Ebay that can withstand 99degC. I used to hate relying on the PRV, and understand that fitting an expansion tank is kinder to the calorifier?

I used to hate immersion heater jobs, cause I could never get the swines to undo! Never changed one in a boat yet, but can see that vibration might loosen them. I tried to undo one in a house once that had been "stagged" in and the top of the copper cylinder ripped. After that I never forced them, and on one occasion left the dead one in, and got a plumber to put a new flange in so I could fit a new element. Sorry I am drifting again....

Loosen them while the cylinder is still full of water helps

[Guest]

Loosen them while the cylinder is still full of water helps

Agreed. Also sometimes they would undo better if you actually turned them in the direction of tightening a little first for some reason. Not my favourite job, especially as many cysterns in houses have no drain facility.

[Dibbo]

Just a quick addition, as I'll need time to examine everything to do with the comments, but after we cut away the insulation away from the nut and heater elements and it filled again, the electrics remained dry, we slid the heater elements out and they were as dry as a bone. How well is the insulation stuck to the tank? Because if its stuck like shit to a blanket then it must be from the nut area.

[Tobymonster]

Those 'heater elements' are probably the thermostats. You can't remove the heater without unscrewing the large nut. If those thermostats are dry when removed then it does point to a leak around the base of the nut. As for the insulation using a wood chisel carefully at an angle that's as flat as possible to the copper skin will remove it quite easily. The tricky part is putting back on!