Relief valve question

lbeachmike

Hi -

On another thread for a different topic, somebody took note the relief valve for my hot water tank and expressed concerns about the mounting height.

Upon closer inspection from a different angle, I see there is another relieve valve mounted flush with the tank. This was not apparent in the previous photo. Is all good here?









Thanks.

Mike

HVACNUT

Everything is fine with what you mentioned. The air eliminator on the tank is a little funky. And the blow off pipe is what material? Is it rated for 210°? The other relief valve should have a blow off pipe as well.
You have a reverse indirect so the relief valve in the tank is rated at 30 psi for the boiler side.
The other relief valve is a domestic T&P (temperature and pressure) valve and its capillary is directly in the path of water flow so all is good.

lbeachmike

Thanks very much. Yes, I noticed that the air eliminator looks like a frosted cupcake

How do I determine the ratings of the pipe you asked about? You are referring to the white pipe?

Re: the flush-mounted relief valve - you are saying it should have a pipe that goes over the side of the tank, so if it triggers the water goes on the floor instead of all over the tank?

Larry Weingarten

Hi, The existing white pipe that has multiple threaded parts looks like it's made for irrigation sprinklers, so it's likely not right. Normal white PVC pipe is not meant to take heat. The flush mounted relief valve should be rated for 150 psi and 210 degrees F. It should also be piped (I like to use metal pipe) over the side of the tank and down to six inches off the floor. This is to prevent anybody getting sprayed with scalding hot water. That air vent should just be replaced. It's seen better days!

Yours, Larry

ps. I'm assuming that the flush-mounted relief valve is on the domestic hot water side. I could be wrong! If I'm not wrong, the valve should be marked for 150 psi and 210 degrees F.

lbeachmike

Ah yes! Scalding risk. Some of these things are so obvious, yet without experience not immediately apparent.

I don't think that pipe is pvc, but I'll check it out. I have no idea to know the rating of that relief valve unless they are marked. I'll have my plumber have a look over the things you guys have pointed out so we can get those remedied. I really appreciate the guidance! You guys are awesome!

Larry Weingarten

I just looked more closely at the tag on top of the tank, by the relief valve and it says fifty psi. So that's not the domestic hot water side of things. That means the relief valve up higher is. Now the problem is to find a way to have that valve actually sense the temperature of the water in the tank, not just in the plumbing. The simplest fix might be to make sure the valve has an extended probe and insulate the heck out of the piping, so the valve sees only the tank temperature. Others may have other ideas.

Yours, Larry

EdTheHeaterMan

There is a problem with the top valve (not the lower valve). This video addressed that issue https://www.youtube.com/watch?v=R5lfB2G8fnQ
The problem is the temperature probe. It is not in the tank. You can see the comparison of the incorrect and correct valve at about the 11:02 minute timestamp on the video. Even with the longer probe valve your probe may not be long enough. You may need to replace some of the fittings on the tank . The best situation for you would be the 3/4" brass nipple in the tank should be shorter. A 2" or shorter nipple is recommended. The Tee fitting should be a brass 3/4" threaded x 3/4" threaded x 3/4" threaded Tee. Then the relief valve temperature probe will be inside the tank. On the branch side of the tee you can then convert to copper to finish the connection to the mixing valve

See this instruction sheet for the Watts brand valve

EBEBRATT-Ed

I agree with @EdTheHeaterMan

that thing isn't right

EdTheHeaterMan

EBEBRATT-Ed said:

I agree with @EdTheHeaterMan

that thing isn't right

Now you got to change it because 2 Ed's are better than one!

HVACNUT

The T&P is in the correct location for this reverse indirect. 
9 out of 10 I come across don't have one at all.

lbeachmike

Now I'm *really* confused. So all is good here after all?

EBEBRATT-Ed

No. Although I admit that with a reverse indirect the DHW pipe in the tank has no real volume so why should it need a T & P the attached shows what Tubomax says in the install manual

HVACNUT

lbeachmike said:

Now I'm *really* confused. So all is good here after all?

All is terrific here. There is no "tank" for the domestic. Where it is is the only place it can possibly be.