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TP valve discharges up and out of the home?


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Question about a strange TP valve discharge line.

So this water heater has a TP discharge line that runs up and out of the house.  On initial inspection, the inspector noted the potential for water to collect & corrode the valve as well as the potential for backflow into the water heater.  Seller "corrected" the problem by having a plumber come out and install a 90 degree elbow with a drain at the upward turn. 

Is this legal/good practice?  My understanding is the line should drain with gravity which to me means that it should go down & over the side of the WH, but this is at the back of a garage and there is no drain in the room to be able to take the overflow if it opens.  What should be the best practice here and is the drain on an elbow really a proper fix for this?





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The Georgia amendment allowing this is dangerous. It violates every plumbing code (must drain via gravity, cannot be trapped, can't have more than 3 90° elbows), and the valve manufacturer instructions. In the event of a high temp or high pressure failure of the water heater, IF the safety valve functions that mess of plumbing is going to burst...either between the first and second elbow or the bleeder cap is going to become a projectile. And that's a big if. The valve is likely to be corroded from water trapped against it and fail to open, turning the tank into a bomb. That water heater would be safer without a drain extension at all.


I was home alone as a teenager when a pressure be vessel exploded. Not an experience I would recommend.

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16 hours ago, Tom Raymond said:

According to most of the Georgia professional inspectors on Facebook, that arrangement is not only allowed, it's expected when there is a basement.

 I don't know why they don't just dump it on the floor like we do here.

GA 2020 Amendments allow up direction but also require visible, safe termination, which is what these pics don't show.

Edited by Jim Baird
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4 hours ago, Jim Katen said:

What's this object? 


After some time on the phone explaining that this made no sense with the plumber, he returned to the house to look at the whole setup.  Said it was some type of pressure relief.  Seems like the original installer tried to get around having a thermal expansion tank by putting a T on the T&P line and running it through this thing and back into the cold water line.  Had me completely baffled. 

Georgia code apparently allows the up & out run of the line, but still doesn't allow a T anywhere on it.  They ended up cutting this out and running the  T&P drain up and out. 

Plumber echoed Tom's statement that running up & out like this is the most common and expected way these are configured in Georgia.  I never saw anything like this while living in the northern part of the country.



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Even given Georgia's plumbing code, it looks like the original plumber went to a lot of trouble to get this wrong. 

For a short time in the '90s (I think it was one code cycle) Oregon used to allow something similar. You could run the discharge line uphill if you drilled a 3/32" hole in the lowest point of the "trap." This was one of those rules that stuck in peoples minds, like GFCIs within 6' of a sink, for decades after the rule was gone. It seems like everyone still thinks that this is allowed. 

I just tell people to run the discharge straight down into a pan. If they're worried about flooding a basement, install a floodstop kit. 



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  • 2 months later...

I believe I live in the same GA county as Jim. This WH was installed in 2007 in one of the corners of my basement. Notice the TPV drain line eventually goes vertical and ultimately has 4 (maybe 5 if there is one on the outside wall), 90 degree bends (one at the top out of sight) <bb

11_jan_21 008.JPG

Edited by rjbrown2
further relevant info on 90 degree bends
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