anyone help with a calorifier question?

RIN

RIN

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We have had water in our engine room bilge for a long time and I have tried to track down the source of ingress in vain. However whilst warming up the engines prior to an oil change, I noticed a trickle of water coming from a pipe connected to the calorifier. This pipe looks like an overflow pipe as it just discharges its contents into the bilge.
There is a feed from the port engine into the calorifier (the top hose), a return to the engine (middle hose) and this waste pipe (Bottom hose).
Image026.jpg

Its the bottom connection in the picture.
Should water be coming out of the pipe? What is its purpose?

PS anyone else on board their boat last night ? It was seriously rough
 
It's a pressure relief pipe. If it is constantly leaking, the valve will need replacing. If it surts out occasionaly it can be rectified with an expansion tank.
 
It's normal overflow. I cope with it by leading the hose into a plastic bottle wedged in the bilge. It seems to get about half full then I empty it - about twice a season.
 
If your system is pressurised it will be a pressure relief valve. If non pressurised ie open vented it will be a DOC drain-off cock.
If the former best to change the valve. If the latter undo it & replace the rubber washer.
 
Yes, it's your pressure relief valve which activates should the pressure in the water system exceed its setting (water expands when it gets hot).

As has been said, there could be a faulty expansion vessel in the system, or there may just be some debris on the seat of the valve. You can test its operation by rotating the knob on the top of the valve which should be srping loaded and rotate on a cam, it will open and let water out. If you do this several times when it reseats it can often clear the debris. Otherwise you will simply need to replace the valve! It opens up the secondary (hot water) side not the primary (engine heating) side so no worries there.

Couple of images to help you ID these devices as fitted to my boat - not exactly the same but anyway:
03032008233.jpg

23022008198.jpg
 
I get this when the air cushion at the top of my tank becomes depleted. This cushion is there deliberately to allow for the increase of pressure as the water heats up.

The instruction manual mentions this and (AFAIR) requires you to shut off the heating source and pressure pump, release any pressure by opening a tap. Then open the valve and allow any fluid to drain - this also replenishes the air cushion. Snap the valve a couple of times to clear any calcification, close it, and it should have stopped dripping.

Hope this helps.

Tom
 
Agreed - It could be a lack of expansion space. However, does your vessel have a shrader (like car tyre) air valve fitted to the top? If so, you also need to check the air pressure to ensure it is charged. Follow the procedure as you suggest then once pressure is fully released use a car tyre pump to replenish/check the air pressure! If it drops you have a leak in the diaphram and the vessel must be changed.
 
I run my prv outlet to my shower sump so when the engines warm up the shower sump gets some clean water through it, stops it going smelly, it's only ever a dribble as I have an expasion tank as well.
 
It looks more like a drain point from your picture but if indeed it is a pressure release valve it looks like replacement would be the best option!

They can be purchased in 2 bar and 3 bar........ 2 is sufficient for the boat?

Draining down to replace will automatically leave air in the top of the cylinder if that is how pressure is absorbed on your system, as stated if it continues to blow water out a pressure vessel is the answer.

Tom
 
Thanks for all the comments everyone.

From memory, the feed to the boats domestic hot water comes from the top of the calorifier. So I guess it isn't designed to have air at the top. There is no other expansion vessel. It does look like a drain point but it is rether large so I will assume it must be some sort of pressure relief valve.
I 'll have a go at replacing it when it gets a bit warmer and see how it goes then. For the time being I'll use PetiteFleur's suggestion of a plastic bottle.
 
RIN: the pipe off the top of your HW Cylinder should be the hot water feed to taps?

On the secondary (HW) side hot water is almost always taken off at the top for obvious reasons and cold water from your tank should enter at the bottom!

I would say it's definately not a drain point (thats not to say some plank has fitted a drain off cock where the PRV should be), it would be daft to place a drain off that far from the bottom of the cylinder!

If there is no expansion vessel it is more likely that the PRV valve has operated more frequently than it should, hence debris depositing on its seat. You may be able to clear it!

I would definately recommend you fit an expansion vessel in the system - almost all of them have a diaphram seperating the air and water sides. You should only get air out of the schrader valve not water, otherwise the diaphram/vessel is knackered!
 
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