What is this copper fitting?

Hi all!

Attached here is what I found in my new house, where the previous owner had his washer/dryer- this is an outside wall, in the basement, with a floating wood floor 1" above concrete slab.

Both valves were within the wall, as well as the standpipe, with vapour barrier cut up as seen in first picture. Decided to open up to inspect and correct- I will be installing a laundry sink next to this, with a washer draining in the sink.

In the second picture you will see what I found, and I have a question:

1- the front copper is hot, with the back cold; what is that Zurn part that is right before the cold water tap? Also, the pipe leading down into the ground is actually broken at the union (can’t be seen, but I can actually separate the pipe in two), and when I turned the tap on water came out the tap but not from the pipe leading down. I don’t understand what the purpose of that pipe going down is?


Dave Ruel

Hard to tell for sure as I cannot zoom in but it appears to be a pressure relief valve, not sure why or for what design purpose. Pipe below would be to drain somewhere other than directly on floor. Check your hot water tank to see if valve looks similar to that. Home may have natural high water pressure. Pressure range may also be stamped on valve. I have encountered that on a couple of homes with artesian wells. Pressure relief valve put in place to prevent fixtures from blowing seals.

May be a trap primer to keep a the water seal in the floor drain from going dry. They are ususally plumbed with a small 1/4" copper tube, but everything about this looks unorthodox.

Any numbers cast into the valve?

Thanks for the replies.

No numbers of markings other than Zurn. If I look inside from under, looks like a spring or screw or some sort.

I’m not home, but I’ll check if there’s another near the hot water tank.

Chad is correct it is a ZURN Trap Primer Model 1171288 retails for about $50.

Here is a web link: http://www.instawares.com/trap-primer-1-ea.117-1288.0.7.htm


Here’s a much better picture…

If this is indeed a trap primer, I don’t know where the floor drain is. Can it be under the floating floor somewhere, or does it have to be accessible?

Is this trap primer something I want to keep and work with, replace with a new one, or just scrap?


I’ve confirmed that it is a trap primer- there’s another exactly like under my sink in a bathroom upstairs where there’s a floor drain. When I turned that faucet on, you see a small jet of water shoot down into the pipe below.

However, when I inspected the one in question here in the laundry room, no water seems to flow out. Do these turn on every time water goes through them, and can they stop working? Should I replace it?

Thanks again!

Yes, they can and do stop working. Usually due to hard water. I’ve replace a dozen or so in the last 10 years.

What is correct is to have that drain exposed, with or without the primer. If your basement ever floods, you’ll be glad it’s there.

I see that style of trap primer regularly in my area with municipal water that is soft and of good quality. The vast majority are not working; would not recommend that trap primer.

In many newer homes with finished (many by owners) basements, it is not unusual to not be able to locate the floor drain which I know is there somewhere. A few times in unfinished laundry areas with bare concrete slab, I have seen small area carpets covering the floor drain in front of the appliances- got to keep those toes warm!

Thanks for the advice, folks.

Here is my revamped plumbing- the drain and valves are under a laundry sink (not shown), with a tee going to a ball valve for the sink and another valve for the washer.


Picture 1

Picture 2

Thank you!