Calorifier installation query

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Slowtack

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I am replacing my calorifier. In the existing system, 33 years old, the drain pipe from the pressure relief valve is not vented to the bilge but connected to the cold water supply line from the water storage tank just upstream of the pump. It gives rise to a brief pressure increase after a hot run and possibly affects the PRV performance although the storage tank surface level is below the level of the PRV. I welcome any comments on this arrangement and whether it is commonly used.
 
Slowtack said:
I am replacing my calorifier. In the existing system, 33 years old, the drain pipe from the pressure relief valve is not vented to the bilge but connected to the cold water supply line from the water storage tank just upstream of the pump. It gives rise to a brief pressure increase after a hot run and possibly affects the PRV performance although the storage tank surface level is below the level of the PRV. I welcome any comments on this arrangement and whether it is commonly used.
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Sounds like a strange setup. If it were me I think I’d vent it in to the bilge or install a skin fitting and connect to that.
 
For what it's worth, mine goes into a square plastic bottle maybe 1.5l in size that looks to have been made for the purpose. It needs emptying about twice a season; I made a bracket from which it can be easily lifted out and tipped into the sink.

Pete
 
Slowtack said:
I am replacing my calorifier. In the existing system, 33 years old, the drain pipe from the pressure relief valve is not vented to the bilge but connected to the cold water supply line from the water storage tank just upstream of the pump. It gives rise to a brief pressure increase after a hot run and possibly affects the PRV performance although the storage tank surface level is below the level of the PRV. I welcome any comments on this arrangement and whether it is commonly used.
Click to expand...

If the hot water system has an expansion tank fitted the calorifier relief valve should not normally lift. In which case its vent can simply be directed into the bilge without any problems arising.

See https://www.jabscoshop.com/files/Accumulator and Expansion Tank Instructions ZPWL4 doc595.pdf
 
On my last boat, when I installed a new tank I just had it venting to the bilge but ended up just putting the hose in to an empty two litre lemonade bottle which I just emptied every now and then. Kept the bilges clean that way.
 
Slowtack said:
I am replacing my calorifier. In the existing system, 33 years old, the drain pipe from the pressure relief valve is not vented to the bilge but connected to the cold water supply line from the water storage tank just upstream of the pump. It gives rise to a brief pressure increase after a hot run and possibly affects the PRV performance although the storage tank surface level is below the level of the PRV. I welcome any comments on this arrangement and whether it is commonly used.
Click to expand...

I agree with others, just put the hose from the prv into a plastic bottle. Mine is 1/2 litre.

www.solocoastalsailing.co.uk
 
It might be worth looking at the manual for the prv. Some require the valve to be exercised at intervals so that you know they are not sticking. A hose into a plastic bottle is ideal.
 
I already use a 5l plastic bottle for the antisyphon valve drain......dual use now. Thanks all for your replies.
 
Slowtack said:
I am replacing my calorifier. In the existing system, 33 years old, the drain pipe from the pressure relief valve is not vented to the bilge but connected to the cold water supply line from the water storage tank just upstream of the pump. It gives rise to a brief pressure increase after a hot run and possibly affects the PRV performance although the storage tank surface level is below the level of the PRV. I welcome any comments on this arrangement and whether it is commonly used.
Click to expand...

That’s almost the same system as mine. My PRV is connected to a fitting feeding back into the aft water tank, been like that since the boat was made and works just fine.
 
IanL said:
It might be worth looking at the manual for the prv. Some require the valve to be exercised at intervals so that you know they are not sticking. A hose into a plastic bottle is ideal.
Click to expand...

On exercising: All my radiators at home have thermostatically controlled valves. They were failing quite frequently, requiring replacement. Then I found that if I remove the control head and rotate the needle valve with a pair of pliers the valve is back to normal. Saved a lot of money and time.
 
duncan99210 said:
Because that’s the way it laid out in the boat manual.....

And it was obvious from looking at the layout that it had been built in from the get go.
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Yes, but if the outlet from the PRV is piped into the water tank, for all you know, it could be passing all the time.
 
Duncan 99210. If mine drained by gravity into the tank over surface level I would leave it be. However it connects to a point below tank base level ...... hence the occasional pressure buildup in the system as I described. Plastic bottle for me now!
 
NormanS said:
Yes, but if the outlet from the PRV is piped into the water tank, for all you know, it could be passing all the time.
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If it was doing that, the pump would be running constantly and the cold water would get hot..... Been that way for 19 years now with no problems, including 6 years full time live aboard. I see no reason whatsoever to change the layout, especially not to one where the PRV vents either to the bilge or a bottle.
 
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duncan99210 said:
If it was doing that, the pump would be running constantly and the cold water would get hot..... Been that way for 19 years now with no problems, including 6 years full time live aboard. I see no reason whatsoever to change the layout, especially not to one where the PRV vents either to the bilge or a bottle.
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Oh well, as long as you're happy with such a sloppy installation. :rolleyes:
 
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