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pjb999

HW tank failure, pressure issues et al

pjb999
15 years ago

I posted a couple of weeks ago about my hw heater leaking near the t&p valve, I know there's pressure issues because there's a pressure regulating valve and no expansion tank.

The hw tank is out of warranty and I think is failing so I will replace it anyway. Because it's gas the wholesaler (they have a couple of tanks at half price so I want to buy there) won't sell to me because I don't have the requisite gas ticket, although from what I understand it's pretty easy to swap out...so I will need a plumber to do the gas hookup and purge for me, I am going to get it all roughed in since I don't like the way it's currently plumbed...

It was suggested to me that I check the water pressure to see what's what so I bought a gauge and a fitting for a hose bib and hooked them up - with no taps on, it reads 120 psi, with a tap running full, it runs 60 psi and twiddling with the pressure setting adjustment does not seem to shift these values. According to literature I've downloaded, it says the regulator is working ok if I get those readings, but there's a problem with thermal expansion. I do have a problem there in the absence of an expansion tank (I checked with the city, there is no requirement to have an expansion tank even if you have a prv, water meter or other device incorporating a check valve) and I also shut off flow to the hw tank, turned gas down to pilot and eased the T&P valve, but I still got the same readings.

The PRV I have (Watts 25AUB) incorporates a ss strainer in the body, as far as I know it's never been cleaned, certainly not since 2006. Could that have some bearing on it?

Meantime I'm going to rough in the new feeds for the new tank including a whole-house filter, plus a provision for a future attachment to a drainwater heat recovery setup, and a bypass of the water filter for the hose bibs - so there's a few modifications planned. I will discuss the pressure findings etc with the plumber when I organise one and will probably just connect to the existing hw tank from the new pipes til then.

Am I reading the pressure situation right? I am going to go with an expansion tank anyway, it seems only sensible and I don't want hot water intrusion into the cold supply.

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