Return to the Plumbing Forum | Post a Follow-Up

 o
Pressure Relief Valve - Is it needed

Posted by dave6768 (My Page) on
Sun, Apr 14, 13 at 12:03

The Hot water heater has one along with a expansion tank. There is another pressure relief valve that was original to the house (built 15 years ago.) The expansion tank was added with a replacement hot water heater about 5 years ago. Is the this second pressure relief valve needed, or can I remove it?


Follow-Up Postings:

 o
RE: Pressure Relief Valve - Is it needed

The one on the water heater is required by many codes and is the most crucial one in my opinion. Not sure which you mean by the "second" one.


 o
RE: Pressure Relief Valve - Is it needed

Some places require a separate PRV if supply pressure is high. Best to ask a local plumber or look up local code requirements.


 o
RE: Pressure Relief Valve - Is it needed

I understand the one on the hot water heater. There is another pressure relief valve that was installed when the house was built. It's this other valve that's in question.

Yesterday, I disovered that valve was leaking. Discovered that the pressure reducing valve coming into the house was shot and repalced it. The pressure in the house was 90 psi. After replacing the PRV, this other pressure relief valve was still leaking (but not as much.) So, I have to replace or remove the offending valve.


 o
RE: Pressure Relief Valve - Is it needed

Dave,

Sounds like you may be confused between a PRV (pressure reducing valve or pressure regulating valve) installed at the water service entrance and the T&P (temp & pressure) relief valve installed on the WH.

A PRV is installed at the service entrance to lower the street pressure to an acceptable PSI for the houses plumbing. Depending on water conditions they go bad and need to be replaced from time to time. They are usually set to around 60 psi.

A T&P relief valve on the WH is a safety device and is installed so the water heater doesn't explode if pressure problems arise. When these T&P valves leak they MUST be replaced and with EXACTLY the same specification part or maybe... BOOM.

The expansion tank should be check annually when you drain your water heater. You do drain your WH annually don't you?. To do that you put an air gauge on the air valve. If the bladder has failed then you'll get water out of the air valve. If you don't get water then you must drain all the water from the tank, which usually requires removal, and the air bladder needs to be pressurized to what the water pressure is when the tank is empty.


 o
RE: Pressure Relief Valve - Is it needed

Nope...no confusion. There are three valves. The pressure regulator on the line coming into the house, the T&P relief valve on the water heater and a third pressure relief valve that has the vent line running outside. This third valve was leaking...I replaced it today. My question is do I need this third valve. If not, I'll unscrew the new one and put in a plug.


 o
RE: Pressure Relief Valve - Is it needed

Is the third valve a T&P valve? If it is they are cheap and there's nothing wrong with having two. Might be code in your area to have two.


 o
RE: Pressure Relief Valve - Is it needed

"Is the third valve a T&P valve? "

Probably cheaper and easier to find than a pressure only valve since every water heater requires one.

PRVs typically turn the house into a partially sealed system since they do not allow back flow.

This post was edited by brickeyee on Mon, Apr 15, 13 at 10:13


 o
RE: Pressure Relief Valve - Is it needed

It's just pressure and I found one at the second hardware store I went to for about $8. Rather than take the risk that it was code, I just replaced it. It was easy enough to do. Next time, It will only take 30 minutes to swap instead of 1.5 hours. :-)


 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!


Return to the Plumbing Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.


Learn more about in-text links on this page here