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Discussion Starter · #1 ·
I have a 1/2" od PVC outside my home with a steady drip of water. It is a few inches above the line that runs to the TPR valve on the water heater (confirmed by opening the valve). It's not the AC condenser line either. There are two more for them and I checked both units in the attic to confirm there was no water coming from the lines.

Top of water heater - i.stack.imgur.com/Igxp9.jpg

Looking at the top of my water heater, I'm baffled on what the set up is. I'm guessing one or both of the mystery 1/2" lines running off the hot and cold lines are the source of the drip in the 1/2" line outside since it's next to the TPR line and right on the other side of the wall from it.

As a guess, I figure they are there to relieve pressure instead of having an expansion tank? The pressure coming out of the tank drain is @ 50 PSI. When I cut off both the gate valves on the cold water line, the drip is still there so that leaves me thinking it's the hot water line.

Unknown valve - i.stack.imgur.com/Hn2i1.jpg

I believe the culprit is this valve coming off of the hot water line. I don't exactly what it is or why it is there. It's sprayed over with paint but it is a metal valve of some sort. It reminds me of a needle value for a hydraulic line which might make sense if it's some other mechanism to relive pressure but I think it's more likely a ball or gate valve I'm not familiar with.

Anyone know what this valve is and what it's purpose is? I'd love a larger explanation of why the 1/2" line on the cold water exists as well but my main priority is to determine what the one on the hot water line is and replace it to see if that stops the drip.
 

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I'm no plumber but it looks like it could be a TPR valve on the hot system. I've never seen such a thing but perhaps your jurisdiction did/does require one. The branch on the cold circuit might a system drain. You mentioned attic a/c which tells me you may have no basement and perhaps no floor drain in whatever room the HWH is in. Perhaps these branch were installed as a way to drain your lines to the outside.
 

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Discussion Starter · #3 ·
Ya know, I ruled that out because the tank obviously has a TPR on it already but it might just be a PRV. If it wasn't painted over, it would look like what Google is showing for a poppet style relief valve. Thanks for that input!
 

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Ya know, I ruled that out because the tank obviously has a TPR on it already but it might just be a PRV. If it wasn't painted over, it would look like what Google is showing for a poppet style relief valve. Thanks for that input!
I agree, being how there is no expasion tank, that sounds about right. I see an arrow on bottom but everything else is painted over. Maybe some sort of tempering device???. Idk. As you stated, the TPR valve is the one coming out of the wh.

The plumbers will be along soon for more advice/suggestions.
 

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Discussion Starter · #8 ·
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