what is this on the water heater???

I found this on a water heater during a 1 yr warranty inspection. Anyone have any idea what it is for??? yes there is a recirculating pump on the water heater.

any ideas out there?

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See this link

It may be a Wilkins HBRV

Data Sheet

Interesting setup. A electric water heater with a bypass valve upstream of the shutoff valve that dumps into the TPR discharge pipe. Is there solar water heating in this house?

The last picture is a hot water recirculation pump that may have been installed afterward the initial installation. It could also be part of a solar hot water heating system too.

In this case the Pix are not giving enough of the story


It looks as if it’s a pressure relief valve. Maybe in case the pressure within the pipes is exceeded too high the valve will discharge relieving pressure on the pipes and potentially saving the joints from failure??? Hmmmm never seen one yet.

What does the tag on the valve say. Air Relief ??? Never seen one like it.

I’m inclined to agree with Mark. Definitely looks like a pressure relief valve. Never seen one plumbed exactly like that, but have seen them on hot water radiant heating systems with circulating pumps.

what is a Wilkins HBRV?

no solar system on the house. the house is less then a year old. Not sure what the tag says right now, but I’ll look and get back with you.

thanks for the help everyone! BUT I still have no idea what it is.

Click on this LINK and view model HBRV spec sheet (top item on page)

The HBRV is for hose bibb applications but it looks very similar.

there is no hoes bib here. one end of the copper tubing goes from the T&P valve back to the top of the water inlet line.

Could it be a pressure relief line to control the pressure coming into the water heater? As the pressure get too high it goes off and drains into the relief drain line?

Monday I think I’ll call the builder and then talk with the plumber to determine what it is…

Sorry Doug. Didn’t mean to confuse the issue. It looks like a pressure relief device that is similar in design to the HBRV hose bibb model. Check for other markings on the device for better information.
As you said the device discharges to the TPR valve drain line and is used instead of of an expansion tank.

I was thinking it looks like a setup for an outdoor sprinkler system.

What are you smok’in Ken.:shock:

What happens when the TPR valve needs to be activated? There is no way that tapping into the TPR drain line like that can be right. If it is I would sure like to know.

Okay, I talked with the plumbing contractor today that installed the water heater, etc. about the copper line in question [photos on first post above]:slight_smile: . It turns out it is an expansion shut off valve. Apparently there are cities around here that are requiring this expansion valve. As I was told, it is designed to relief the pressure in the in-coming water which should eliminate the air gaps we sometimes have when a plumbing repair is completed. An example would be when the lines have been opened, air enters the lines. We then turn on the water and get lots of air before we actually get any water. That’s why this devise has been installed!! As I was also informed, apparently someone with too much time on their hands and a truck load of expansion valves for sale, thought this would be a good idea if it was installed on every new home as a city requirement.

So there you have it…keep your eyes open it may be coming to a city or town in your area! :shock:

It is hard to tell from the photos, but the timer on the bottom has nothing to do with that contraption on the top of the WH. I have seen that type of timer on sprinkler systems.

O.K. Douglass, what about the timer down at the bottom, did you ask him about that?

recirculation loop timer.