Burst hot water tank

[Coots Forever]

Hello,

 

my partner and I are very new live aboards, we got our new home last week.

 

We went on a bit of a cruise to get used to her, all was going well, we ran low on water yesterday & filled up today. & this evening discovered that our hot water tank has burst a leak. Looks like the tank exploded.

 

We have shut everything off. Water pump & stop cock are off. We are a day from home, so will be ok to go on tomorrow.

 

We will need to replace the tank, but are at a loss on how this happened. We don't want it to happen again!

 

Any thoughts on what could have happened and how to avoid it.

 

We were ready for the learning curve, but a little shaken by this.

 

Thanks Coots Forever

[Robbo]

Any thoughts on what could have happened and how to avoid it.

 

The tank should have a PRV valve to release the pressure. I would be very surprised if it didn't.

 

 

edit to add...

 

Also in addition you could add a expansion tank after the hot water tank (more commonly know as a calorifier), this basically stops the PRV from dribbling when you heat the water up.

Edited August 16, 2009 by Robbo

[RLWP]

Hello,

 

my partner and I are very new live aboards, we got our new home last week.

 

We went on a bit of a cruise to get used to her, all was going well, we ran low on water yesterday & filled up today. & this evening discovered that our hot water tank has burst a leak. Looks like the tank exploded.

 

We have shut everything off. Water pump & stop cock are off. We are a day from home, so will be ok to go on tomorrow.

 

We will need to replace the tank, but are at a loss on how this happened. We don't want it to happen again!

 

Any thoughts on what could have happened and how to avoid it.

 

We were ready for the learning curve, but a little shaken by this.

 

Thanks Coots Forever

 

What an awful thing to happen. Is it really the tank that has burst or is it one of the fittings going to or from the tank?

 

Richard

 

(I read all of the Arthur Ransome books as a child)

[Coots Forever]

The tank is fitted with a PRV and has a calorifier.

 

The tank had a hole on the side that wasn't there yesterday, the insulation is splayed outwards like an explosion and water was pouring from it. The water pump kept pumping today and the bilge filled with water very quickly. We've emptied the bilge and shut off all the water. We will order a new tank and fit it, but need to know if it's just a faulty tank or if there's anything else that might have caused it.

 

Any help from anyone who has had any experience of this kind of problem would be most appreciated. Thank for everyones support.

 

Coots forever xxx

[RLWP]

The tank is fitted with a PRV and has a calorifier.

 

The tank had a hole on the side that wasn't there yesterday, the insulation is splayed outwards like an explosion and water was pouring from it. The water pump kept pumping today and the bilge filled with water very quickly. We've emptied the bilge and shut off all the water. We will order a new tank and fit it, but need to know if it's just a faulty tank or if there's anything else that might have caused it.

 

Any help from anyone who has had any experience of this kind of problem would be most appreciated. Thank for everyones support.

 

Coots forever xxx

 

Wow! You really have got a burst tank! That's very unusual.

 

Do you know if your PRV was working?

 

Richard

[Robbo]

The tank is fitted with a PRV and has a calorifier.

 

Presume you meant the tank is a calorifier? When replacing the tank make sure you do get a calorifier and not a domestic hot water tank, calorifiers are built to handle the extra pressure that a marine life and engine heat gives it. Also make sure you get one with two coils, even if your current one only has one, and a immersion heater (or at least the hole for one!).

[RLWP]

<snip> and not a domestic hot water tank, calorifiers are built to handle the extra pressure that a marine life and engine heat gives it. <snip>

 

AND DON'T DO THIS!

 

an aquaintance of mine used to use a domestic hot water cylinder as an air reservoir for a compressor. He did hydraulic pressure test it first to make sure that it was OK.

 

Richard

 

p.s. DON'T DO IT

 

p.p.s Our domestic cylinder runs at mains pressure with coils at three bar

[Yoda]

I think a new pressure relief valve is also called for.

[RLWP]

I think a new pressure relief valve is also called for.

 

I'm not convinced that you can generate enough pressure to rupture a good calorifier with the equipment on a narrowboat. This sounds like a faulty cylinder to me.

 

Richard

[DHutch]

I'm not convinced that you can generate enough pressure to rupture a good calorifier with the equipment on a narrowboat. This sounds like a faulty cylinder to me.

 

Richard

Well no, because theres most likely a non return valve to prevent returning down the cold inlet, shut taps on the outlet, and then you heat the water to 85 with the engine cooling loop. Which is why you have a presure release valve.

 

 

Daniel

[denboy]

I'm not convinced that you can generate enough pressure to rupture a good calorifier with the equipment on a narrowboat. This sounds like a faulty cylinder to me.

 

Richard

yes you can got the tee shirt,,,also check the presure on the water pump mine was way too high

[Coots Forever]

Thank you everyone for your advice and support.

 

Its good to know what we need to replace, & to understand the system a bit better, we will get a new twin coil calorifier & pressure release valve. I have googled some suppliers in the area.

 

We are safely tucked up, I've had a large gin, the bilges remain empty and we've not sunk. So feel a little better! All part of the adventure!

 

Thank you again

 

coots forever

[RLWP]

yes you can got the tee shirt,,,also check the presure on the water pump mine was way too high

 

Go on then, I'm interested. What's the bursting pressure of a calorifier?

 

Richard

[nb Innisfree]

Just a thought but was the PRV fitted the right way round? if accumulator was pumped up too high + faulty valve and 80+ deg water then I think pressure might be enough to rupture a calorifier? (hydraulic locking)

[Coots Forever]

yes you can got the tee shirt,,,also check the presure on the water pump mine was way too high

 

That's a good idea, how do I check the pressure? Xx

[denboy]

Go on then, I'm interested. What's the bursting pressure of a calorifier?

 

Richard

have no idea but when its full of very hot water and your pumps kicking out 48 psi instead of 30 and the prv sticks the seam on the tank goes bang

[RLWP]

have no idea but when its full of very hot water and your pumps kicking out 48 psi instead of 30 and the prv sticks the seam on the tank goes bang

 

Well, stap me vitals! The Vetus tech spec says set your relief valve to 56psi click

 

Not a lot of help that. What's its designed bursting pressure?

 

Richard

[nb Innisfree]

Well, stap me vitals! The Vetus tech spec says set your relief valve to 56psi click

 

Not a lot of help that. What's its designed bursting pressure?

 

Richard

 

It's designed for a safe max pressure of 5 bar/75psi which isn't a lot, I would hazard a guess that hydraulic locking will easily exceed this.

[cotswoldsman]

I'm not convinced that you can generate enough pressure to rupture a good calorifier with the equipment on a narrowboat. This sounds like a faulty cylinder to me.

 

Richard

 

I guess not a good calorifier but it does happen, mine was under 2 years old on a new boat and it split at the weld from the top part to the main tank. Sorry I am not very technical!!!

[Tiller Slave]

Split calorifiers are quite common on narrow boats- it has happen to me on two different boats I owned.

They tend to get small holes in the welding at the shoulders of the tank.

 

It is always a good idea to assume they will eventually go , therefore install them in a place where leaking water will not cause further damage i.e. not under the bed!

 

The normal cause is the pressure relief valve being set at the wrong pressure.

 

Boat builders often get confused between PSI and Bar.

 

Also check the setting on your water pump- many are variable.

[Robbo]

Boat builders often get confused between PSI and Bar.

 

No wonder they blow up then!

[mikevye]

Thank you everyone for your advice and support.

 

Its good to know what we need to replace, & to understand the system a bit better, we will get a new twin coil calorifier & pressure release valve. I have googled some suppliers in the area.

 

coots forever

 

Surecal will supply you with a bare shell + insulation at substantial savings, you simply put Hep2o fittings straight onto the stubs and get rid of the need for compression fittings, simples.

Edited August 18, 2009 by mikevye

[Robbo]

Thank you everyone for your advice and support.

 

Its good to know what we need to replace, & to understand the system a bit better, we will get a new twin coil calorifier & pressure release valve. I have googled some suppliers in the area.

 

You might want to look at a accumulator on the hot water line (goes just after clarifier on hot water pipe) as well, this will stop the PRV from dripping.

[Odana]

Don't know how major your 'burst' was but if the tank had developed a pinhole it might have been something growing over time. I discovered a burst tank because my pump kept kicking in more and more frequently - a pinhole in the tank had blown all the insulation foam outwards and as soon as I cut this off to investigate it just squirted water everywhere. I think what had happened was that my calorifier had been sitting on a bit of damp an inadequate padding on the hull and was basically acting as a very expensive anode.... The spot that went was on the side though. In any case, new calorifier was installed on a wooden latice base well away from the hull, just in case

[Coots Forever]

Hi everyone,

 

Just to give an update, after a few days of my partner and my dad getting soggy feet, we have fitted a new calorifier etc, and followed some of the advice from you guys, so back to enjoying our new live aboard! Phew!

 

We learnt a lot, got to know our boating neighbours (who were helpful and sympathetic) and we know the blokes at the local plumbing supplies shop pretty well too , having popped in 6 times a day for various bits & bobs! We also sampled a few local pubs & indian take aways, for stress relief at the end of the soggy days ... so feel fully initiated into the area!

 

It made a good story at the wedding we went to at the weekend! It's all about having good stories!

 

Thanks again for the advice.

 

Coots Forever xx