All,

Been thinking about the Water Calorifer which will be 12 this year, works absolutely fine (touch wood!!!), but have never done anything to it and not sure if the previous owner did anything to it either. As Harry Houdini would say, it is rather difficult to reach! So is there anything I should be doing as part of my annual maintenance plan (if so, what?) or is it best left alone?

Also does anyone have the capacity size, make and spec for the type of Calorifer installed by Parkers? Also, what is the wattage of the mains A/C immersion element installed inside the calorifier?

Comments welcome.

Thanks Stuart

Pegasus 325/37

Original Equipment fitted to 285 & 325/335

20L WATER STORAGE HEATER VERTICAL (Inc Z/TPRV Pressure relief Valve) Part No CWB21-V3

Optional 240V IMMERSION HEATER 1.25 kW Part No CW278

From Cleghorn waring

http://www.jabscoshop.co...-systems/c-warm-heaters/ 

Thanks Bob!

The pressure relief valve needs turning manually at intervals to ensure it is able to function. I get my crew(!) to do it about every three months.

Also, very important to drain the whole freshwater system when there is danger of frost. There are at least two methods which are described in the archives.


Mike Lockwood
Lucky Devil
Parker 325/35

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My calorifer is spraying water from the pressure release valve. It happens as soon as the freshwater pump is switched on!
It is very inconvenient as I am on a trip. Any ideas?

Mike
Shemar

When ours failed off the west coast of Scotland, I took the valve out fiddled with it and removed the temperature probe from the inside, it remained watertight until I could get a replacement part. We had lost overheat protection but it would still have released if there had been excess pressure in the calorifier.

Good luck

Martin
335/50 Tringa

Hmm - as part of Nosey's engine replacement the calorifier had to be plumbed back in. As part of that, my attention was drawn to an 'overflow' pipe that simply emptied into the bilge! (and had been, unnoticed, since I owned Nosey). Was this pipe part of the pressure relief/expansion system, I wonder. I've now run the pipe into a plastic bottle which I can empty after an engine run.
Perhaps I should investigate further do you think?

John
Nosey 325/26

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Many thanks Martin, I will have to investigate when I get back home. I have a manual water pump at the galley sink so at least we can use that on this trip.
It may be that the pressure relief valve is faulty. Or I wonder if the freshwater pump could be faulty. I hear the sensor switch often goes wrong and maybe it keeps charging the calorifer? But I don't really know how they work. At least it will make me look at the calorifer. I have never even seen it as it is under a false floor in the cockpit locker. I presume this is where yours is.

Mike

I am pretty sure the pressure relief fitting is a common plumbing part with a 1/2 in BSP thread. About £15 ish and not especially marine. Removing the old one will drain the calorifier water into the bilge and can be pumped out to test bilge pump..... Temp fix could be to blank it off as you are not likely to overpressure the calorifier on your trip.
Cheers Malcolm

Have you tried Mike Lockwood’s solution? That did the trick with my calorifier. You have to turn the knob until it gives a big “cloinck” sound from the spring inside. Do it a few times. If that doesn’t work the solution is replacing it. Indeed this is a standard over-pressure valve.
Succes and have a nice trip!

Sorry to join the thread so late. For what it's worth I had my first bout of calorifier trouble, luckily just before setting off but definitely added to the stress!
John - my pressure relief valve drains through a pipe into the rudder rod box, thence out to sea. Good in principle, but not when it started releasing constantly and began to rot the wooden drip tray on the inside face of the transom, so...
Mike B - the helpful people at Penguin Marine down the road on Hayling advised removing the PRV and soaking it overnight in vinegar, this improved things, but not completely cured it, so...
Malcolm - I bought a new PRV, I found it is not easy to get exactly the right temp and pressure but something close should do it, but it took a while to come and while I was waiting...
Mike B again - I had the brainwave of replacing the little Whale flow switch next to the FW pump, which I had thrown away a year before when it stopped the whole system and I thought it wasn't important. Turns out it was, and it was by far the cheapest and easiest replacement of the lot. No idea why you need this as well as the pump, which only switvches on at low pressure, but it turns out it was presumably over-pressuring the system. WHen I had the pump on and hot water at the same time (engine or immersion) the PRV was delivering a cup of scalding water onto the rudder box every hour or two, and sometimes into the bilges as well.

Since then, no problems (or none that I have found yet) and I have been doing a lot of motoring...

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Peter, very informative. You had a "wooden drip tray on the inside face of the transom"?! Either a Bill P or a previous owner mod. That's quite a long run. I wonder if a previous owner of mine decided just to let it run into what passes as bilges on a P325. It was pretty nasty where it had drained, and the wood work was - unpleasant.
Good point about a prv next to the water pump. I shall check to see if I have one - I've never noticed one.

Since I've put the overflow bottle in I can see exactly how much (hot) water I lose. I think it happens motoring though - I don't even have to run the pressurised water system.

By the way, we're having a soft southern version of your Scottish weather down here.

Cheers, John

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On Surprise the overflow of the calorifier is a yellow hose that ends in a plastic bottle near the propeller shaft. This way one can see if water is coming from the calorifier … or elsewhere



By the way, I have a new water lubricated propeller shaft seal since last winter, as part of the project to solve the vibration problem.

Thanks both, that sounds like a good mod and one that could easily be done while stormbound in (for instance) Tobermory...

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Hi Peter,

I had to look up Tobermory on Google Maps . I remember the name from articles in Yachting Monthly and I now have refreshed my memory: it’s on the Isle of Mull. Mike B send me the link of your voyage around the UK, so I read about your experience. Great reading. I still have to get started sailing at sea …

Thanks everyone. I have been busy but finally got round to emptying the cockpit locker and taking up the false floor. I have turned the PRV as suggested, many times. However, every time I switch the freshwater pump on the PRV discharges loads of water instantly. About 2 litres in 5 seconds!
I am planning on removing the PRV. But how to drain the calorifer? I thought of disconnecting the cold water feed from the calorifer. But people say that there is a non return valve in the calorifer which will prevent it draining? How did you remove your PRV Peter?
Also, I don't have a whale flow switch on Shemar and the calorifer has worked well for 20 years. What is this? I tried googling it but not much luck. Should I have one?

Hi Mike, I know how to drain the calorifier. I was instucted by the previous owner and did it last autumn. Switch off the FW pump and the heating of the calorifier.
In the cupboard under the sink you have the remove the bottom shelf. There are two copper pipes that are connected to the cold (blue) and warm (red) hose that go to the tap. Disconnect the blue hose from the copper pipe and drain the calorifier in a shallow beaks until it is empty.
This is part of my preparation for the winter.

Thank you Dirk. I have some news. I realised that I could remove just the valve without removing the whole unit including the temperature probe and drain tap. This was quite easy using a 27mm spanner. When I removed it, the calorifer drained slowly via the drain tap hose into my bilge which I collected in a bottle. I descaled the valve and then refitted it. But it still did not solve the problem. I now think that my pump is pressurising the calorifer too much and the PRV is then opening as it should. I have read that sometimes the pressure sensor on the pump goes faulty.
So my plan is now to replace the freshwater pump. However, I don't understand Peter's suggestion to have a Whale flow switch. Is this something to do with the pump pressure? Can anyone shed light on this?

Most FW pumps in boats and RV’s do have a pressure switch at the bottom. This switch cuts-off the power to the pump when the pressure exceeds a certain value. In many cases the closing pressure can be varied by a screw at the bottom of the switch. I know this from the FW pump in my previous boat.
If the pressure switch is not working properly, but the pump itself is fine, adding an additional switch may be cheaper than replacing the whole pump. Of course this extra switch needs some available space under the wash basin in the heads.
My advice would be to first remove and inspect the FW pump and check the switch. These pumps can be open fairly easy to inspect and replace solely the switch. I’ve done it successfully in my previous boat.
In Surprise the FW pump is a Flojet pump. The switch off pressure is 1.3 bar according to the label. In this Youtube channel you can see how to replace only the pump switch:



In case of a complete pump replacement many other pumps can be fitted as they are very much alike, just match the max flow rate and closing pressure.

Well, I have fixed the problem. The pressure switch on the Flojet water pump was faulty, and it was over pressuring the system. I decided to change the whole pump as it was 20 years old. I bought a Jabsco Par-Max 3 pump that has a maximum pressure of 1.7 bar.
Many thanks to all who contributed. It has been an interesting experience and at least I got to investigate my calorifer and the PRV - which was doing the job it was supposed to!