Some thoughts/opinions please. Unvented heating system has a caleffi pressure reducing valve, 3 bar with 6 bar safety release valve. System is approx 2 years old. 6 months ago noticed dripping from the safety release valve. Had the full reducing valve changed. Now 6 months later dripping again? What's the odds/chances of two faulty ones in such short period?? Any other possibilities?? or just simple bad luck???!!
Is this a pressure (safety) release or pressure reducing valve? Caleffi is a decent make, I understand, but these fellows - well, the safety-release-valves - are prone to allowing a drip through after they've been activated. Do you know if your valve has been activated? Ie by a pressure build-up that exceeds its trigger level? If so, they can drip annoyingly from then on...
it is a pressure reducing valve (3 bar) on the main inlet feed with a 6 bar safety release valve, it is the safety release valve that is dripping into the tundish, it was doing this approx. 6 months ago and had the full thing replaced, as the 6 bar safety release , although part of full thing, can be replaced separately. But thought best to change the whole thing, and now 6 months later dripping again, to my knowledge not been activated, so annoying faulty again after such short period?, any suggestions what may be causing this? or as I said just bad luck two gone faulty in such short time frame??
Do you have exceptionally high pressure in your area?! If only 6 months old, it sounds like a warranty issue for starters. I'm afraid I don't have much knowledge of these items - I do have a PRV fitted in my own home (and a Caleffi as it happens) but I'm not aware of it having a safety release valve on it. I presume this safety valve it in case the pressure on the domestic side increases too high for some reason? (And 6 bar is high...) What could cause this to happen, I wonder? I'm struggling to think of anything that would cause the 'trapped' domestic side to increase like this. Do you have a anti-'water-hammer' vessel fitted in a place where it could get really hot during the day, enough to cause the pressure to climb? (Extremely unlikely - chust clutching at straws...) Or, could your PRV be allowing some flow-by during the night or day when there's no-one running water, and it's allowing the pressure on the domestic side to creep up to the point it drips out the safety valve? Is there a pressure gauge fitted to the PRV? If so, what does it read first thing in the morn or when you come home from work? When you turn on your cold kitchen tap in the morning, does the water explode out?!!
My understanding is the pressure reducing valve ( 3 bar) is to maintain a level and balanced pressure for cold flow and thus level flow and equal pressure on hot water. There is a expansion vessel also. I would imagine the safety release valve same as the one on the actual hot water tank are there to act if pressure goes to high. But can't understand why this particular should fail twice in such short period?
Like DA says they are temperamental and part of the annual safety check is to make sure that they are in working order, yet this test often results in setting the sods off dripping (the plumber then gets the blame). Make sure that the expansion vessel is fully charged (3.1) this could be the problem if not. I agree with DA 6 bar is very high. Tappy
The vessel shouldn't have an impact on that prv because it will be before the non-return valve,sounds to me either the pressure reducing valve has failed or has cr@p in it,or the relief valve is faulty or has cr@p in it.
Another possibility that I forgot to mention is that the expansion vessel could be undersized - if the EV cannot cope with the amount of hot water expansion in the system it will then have to go somewhere else (the PRV). The charge in the expansion vessel should be the same as the incoming pressure that is set/ controlled by the pressure reducing valve. The 0.1 extra is to cover the small amount of air that you always lose when you disconnect a air line. Tappy,
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