Immersion heater filling bilge with water

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ifoxwell

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I suspect I wont be able to give people enough information to really help but Id like some pointers.

In brief, new to me boat with a hot water system linked to the engine cooling system when motoring and a fitted immersion heater for use in a marina.

Switched on the immersion heater for the first time at the weekend and 30 min later had liters of boiling water flooding into the bilges.

What could be wrong?

Thanks

Ian
 
If the thermostat in the immersion has failed, it could cause the water to boil and the calorifier's pressure release valve will then dump water into the bilge.
 
Where was it leaking from? Overpressure valve, or a hose blown off?

Have you heated it up from the engine before and this was the first time on electric, or was this the first heating by either means?

Possibly the immersion heater has a faulty thermostat, didn't turn off, and when the water got towards boiling the overpressure valve did exactly what it's designed to do?

Pete
 
Immersion heater thermostat not working and boiling the water which then sprays out of the pressure relief valve.

Until you can replace the thermostat (or immersion heater if integrated unit) you could use the immersion heater by leaving it on for say 30 minutes from cold before turing off. If no warm water in bilges you know that this is a "safe" heating interval from cold. Downside is that you have to remember to turn it off!

Richard

Wow! 4 unrelated responses and all agree - impressive!
 
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RichardS said:
Wow! 4 unrelated responses and all agree - impressive!
Click to expand...

And all within 15min of posting.

Thanks guys

In answer to the questions, I cant see any hoses blown off and I don't think it leaks when just running off the engine (although she is still on the hard at present so I've only run the engine for 10-15min while warming up to change the oil)

I couldn't see any external thermostat (although I'm not sure what one would look like) so i guess from the suggestions above that its probably got one built into the heater and that this has failed?

The tank is a pig to reach so the leave on for 30min then turn off idea sounds favorite at present

Ian
 
I'd change the pressure relief valve. It may be letting go before the designed pressure. They only cost a few bob and are available at most plumbing or hardware stores.
 
Almost certainly the pressure relief valve on the calorifier tank. You do click the little knob on the top around monthly to keep the valve seat clean, don't you? Grey knob on http://www.jabscoshop.com/images/CW414 CW415.jpg or may be slightly different on other makes.

No, neither did I click it monthly till mine started filling the bilges. You might just fix it with a few clicks round (a little water should spurt out each time. More likely you need a new valve. Usually these connect to a pipe down into the bilge: now I route a shortened pipe into a half gallon plastic bottle, so I can see how much (usually little) it is letting out. With a valve working correctly I get maybe a pint a year.
 
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jwilson said:
Almost certainly the pressure relief valve on the calorifier tank. You do click the little knob on the top around monthly to keep the valve seat clean, don't you?
Click to expand...

I'm not so sure about that? How would the valve seat have got any dirt into it unless it was opening. And if it was opening, why would it be doing that unless the tank is being overpressurised for some reason?

Richard
 
RichardS said:
if it was opening, why would it be doing that unless the tank is being overpressurised for some reason?
Click to expand...

Mine lets a little bit out each time the engine warms up and the water in the tank expands. I assumed this was normal. I have it routed to a bottle which gets emptied a couple of times a season; I have fitted a float switch to warn when it's getting full although I haven't yet wired it up to a light.

Pete
 
+1 with earlier posters who said the immersion thermostat is the prime suspect - water should certainly not be boiling! If there's no water showing when the engine has been running for a while without the immersion switched on, it's unlikely to be a worn PRV.
 
It's a relatively common problem on some Jeanneaus - the hot water cylinder has a combined pressure relief and drain valve which has an operating handle that is easy to depress and sticks out quite a long way. It is easy to accidentally open it if you store things in the bilge close to the cylinder. I was on a sailing school boat in the North Sea a few years ago when someone noticed that the automatic bilge pump was running continuously - we checked the bilges and found that we had knocked the valve open when we had stowed some supplies - by the time we had noticed, we had dumped the contents of our main water tank overboard and had to severely ration water for the remainder of the passage since we only had the small reserve tank left.
 
NormanS said:
Pressure relief valve on calorifier stuck open?
Click to expand...

Yes, yes, yes! It's the PRV (pressure relief valve) that has failed

Take a look at it. It will have a "bar" pressure reference stamped on it - maybe something like 2.5 or 3.0.

New one will cost you about £40. Fit with PTFE tape on the thread

Jeanneau's pump it straight into the bilge - who the F*** designed it like that?
 
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As the boat is new to you have you checked that the previous owner did not leave the drain valve open after draining the (Quick?) cylinder to prevent freezing damage over winter. On a Quick cylinder the drain valve is a seemingly insignificant black plastic lever on a spring which makes it detent in either the open or closed positions, the lever is on the pressure relief valve. Ours dripped when we bought our boat but the instruction book suggested operating it a few times to clear limescale and it has not dripped since.
 
debenbar said:
As the boat is new to you have you checked that the previous owner did not leave the drain valve open after draining the (Quick?) cylinder to prevent freezing damage over winter. On a Quick cylinder the drain valve is a seemingly insignificant black plastic lever on a spring which makes it detent in either the open or closed positions, the lever is on the pressure relief valve.
Click to expand...

If that were the case, surely the pressure pump would have operated continuously as soon as the batteries were turned on? I don't think that's the cause of the problem.
 
Cantata said:
+1 with earlier posters who said the immersion thermostat is the prime suspect - water should certainly not be boiling! If there's no water showing when the engine has been running for a while without the immersion switched on, it's unlikely to be a worn PRV.
Click to expand...
Another +1. If it's a combined pressure/temperature relief valve - many are - it will be leaking practically continuously if the water gets too hot.

But if the water is not, literally, boiling, then as PCUK says I'd also be looking at the accumulator* or expansion tank - assuming there is one. This too has to be maintained, by repressuring annually. If it becomes depressured, or the diaphragm ruptures, or worse still hasn't been fitted, water expanding on being heated has nowhere to go but out the PRV. When it does the pump will kick in briefly letting in more cold water, reheats, leaks and so on until the bilge is full of water.

One other remote possibility for a PRV leak is the adjustment screw on the water-pump getting accidentally turned so that the whole system is at higher pressure than it ought to be. This can happen with Jabsco pumps.

So there you are, Ifoxwell. If the source of your problem is a leaky PRV, then check PRV, immersion heater, accumulator/expansion tank, water-pump, in that order.

*The accumulator is fitted to even out the water flow, but in a small system can also take up expansion from the calorifier provided no one-way valve is fitted.
 
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prv said:
Mine lets a little bit out each time the engine warms up and the water in the tank expands. I assumed this was normal. I have it routed to a bottle which gets emptied a couple of times a season; I have fitted a float switch to warn when it's getting full although I haven't yet wired it up to a light.

Pete
Click to expand...

I take it with that solution you are a spark, cos if you were a plumber you would have fitted an expansion tank. :)
 
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