one way valve into the calorifier

simonfraser

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just fixed a leak and found a one way valve for the pressurized water into the calorifier.
took it out as it was in the way, seems to still work just fine.

i don't have a one way valve in the hot water tank at home ....

any reason to have one in a boat ?
 

CrikeyChris

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I recently installed a hot water system, originally without a one way valve and was surprised to find hot water coming from the cold tap. The direction of flow seemed dependent on water pressure. I had put in a 5 litre expansion tank (as advised by asap) and I think the pressure within was higher than the pressure from the pump. Adding a one way valve solved the problem.
I have read a system without one can result in triggering the pump as the water within the calorfier cools and contracts slightly.
 

rowlock

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The one way valve is there to protect the cold water circuit from the likes of Legionnaires decease. Might not be obvious but removing it is a risky mistake you may only make once. Houses fitted with roof tanks do not need a valve as the ball cock creates a break between the in, cold, and out, hot, flow for the same purpose.
 

thinwater

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However, the pressure needs to go somewhere. Do you have an expansion tank? In many areas, fitting a heater without either an allowance for backflow or an expansion tanks is a code violation. Yes, there is a PR valve (I hope), but that isn't really enough.
 

simonfraser

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hm the Legionnaires risk is interesting, i don't ever drink the water b4 it's been boiled.
calorifier runs way over 60C so that's not much of a risk, but i take your point.
to keep the water fresh for making tea i have started to run the system dry at the end of the weekend that may mitigate the risk ?

will find out about the hot flowing back into the cold this weekend.
i could blow air backwards through the one way valve, so guess it could do with a replacement if needed.
 

superheat6k

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hm the Legionnaires risk is interesting, i don't ever drink the water b4 it's been boiled.
calorifier runs way over 60C so that's not much of a risk, but i take your point.
to keep the water fresh for making tea i have started to run the system dry at the end of the weekend that may mitigate the risk ?

will find out about the hot flowing back into the cold this weekend.
i could blow air backwards through the one way valve, so guess it could do with a replacement if needed.
The risk of legionella is more one of inhaling the bacteria in the form of an aerosol, e.g. shower heads are notorious breeding grounds, but not desirable to have contaminated water in the cold supply, which may be used for drinking, where of course contaminated water droplets can then be inhaled into the lungs.

In the warmer weather when the boat has sat idle I hang the shower head out of the heads window and let it flow hot water for a couple of minutes to flush out any stagnant water.

The NRVv on my system stuck open when I fitted a new calorifier. I found the water at 80oC was literally blasting from the cold part of the mixer taps until the entire calorifier had emptied, and this scalding hot water was completely bypassing the thermo reg valve, which limits the hot water to 60oC. The NRVv was scaled up and jammed, but a new valve completely resolved the issue. I would definitely refit a new one, they are cheap as chips from Ebay.
 
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