Ask the Question

Destroyer · Joined: 21 Apr 2008 Posts: 3 Location: Springfield, NJ

My 12 year old water heater was leaking from the bottom. The plumber came in and replaced it. Because it was a powervent, it was not a cheap job.

As soon as they left, I saw leaking again. This time, it is from the pressure relief valve on the water heater.

The plumber came back and said the pressure reducing valve on my main line is not responding (he tried turning it and showed me that the water floe on my nearby sink did not change). Now he says I need to get the pressure reducing valve changed.

My question: How come this pressure problem started only when I got a new water heater?

thescruff · Moderator Joined: 03 May 2003 Posts: 4386 Location: Bath

I'm going to suggest a few possibilities, but you most realise we are the other side of the pond so they may not apply.

Pressure relief valves are notorious for leaking once they have been set off, if I was to fit a new appliance as in your case, we would always fit a new PRV.

The other cause which may or may not apply in your case is a pressure reducing valve, have you got one and has it been set.

Expansion vessels again if you have one may not be set or pre-charged.

Finally the water heater may be more efficient and so the water gets hotter and therefor more expansion.

To answer the question yes it's quite likely you need a new valve, but at the same time get the engineer to check his work over.

Destroyer · Joined: 21 Apr 2008 Posts: 3 Location: Springfield, NJ

Thanks for your reply.

With the new water heater, he did change the pressure relief valve 2 more times and each time, it popped right away.

When he installed the water heater, he also put in an expansion tank on top of it as well.

On the pressure reducing valve there is one. However, the plumber thinks it is broken because the nearby sink didn't change flow when he adjusted the pressure reducing valve.

I see your point though that this being a new water heater, it may respond differently than the old one.

thescruff · Moderator Joined: 03 May 2003 Posts: 4386 Location: Bath

Is the pressure relief valve the right pressure, it should be listed in the manufacturers instructions, and could be too low.

The expansion vessel should be pre-charged, did he check and set it according the instructions.

The pressure reducing valve are pretty reliable so unless there is some grit etc got in when the supply was turned off, I would check the above first.

Destroyer · Joined: 21 Apr 2008 Posts: 3 Location: Springfield, NJ

My neighbor had a family friend who is a plumber over and he looked at my plumbing. He had a gauge and on an outside spigot, found my house water pressure at 140 psi, which he said should be at 60-80 psi. He tried changing the pressure reducing valve and it didn't change anything to the other sink there in the basement.

I do not know if the expansion vessel was pre-charged.

So I'll have to get that changed. It's going to be a big job since the city has to come out and turn the water off from the sidewalk, since there is no other valve there to turn the water off.

thescruff · Moderator Joined: 03 May 2003 Posts: 4386 Location: Bath

In that case I would change the Pressure reducing valve, and at the same time fit an isolating valve internally on the incoming mains for future use.

The vessel can be checked while the system is down