Pipe into HWH drain valve???

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Hello,

I would like to hook up my slab hydronic heating pipes as shown in the picture. The exception is that I want to use my current 40 gallon hot water heater.

Is it allowable to pipe the return side from the exchanger into the drain valve of the HWH tank? What if the valve on my tank is plastic?
And finally, if it is allowed does anything need to be added that isn’t shown in the diagram?

Thanks for your time!
B0B94BB9-2475-41DE-B6CF-963C290DE218.jpeg
 

Reach4

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Is it allowable to pipe the return side from the exchanger into the drain valve of the HWH tank?
I would think so. I am not a pro.
What if the valve on my tank is plastic?
What I would do is to install a new brass or bronze tee. Normally the thread on a WH drain is 3/4 NPT. The new pipe would go into the side of the tee, and the new metal drain valve would go into a straight leg.

That plastic drain, if it is like the one I replaced, can be unscrewed into two parts. The thread on the left of the picture is 3/4 NPT. ON the right is a garden hose thread. If I remember correctly, if you unscrew the big diameter enough, you could pull that out. Of course you would expect water to come out while that valve is separated.
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I replaced my plastic drain valve with several parts: nipple, full flow ball valve, GHT adapter. There is now available a brass full flow drain valve, which I would have used instead.
Rheem AP12231C-1 Overall Length (in.): 6-1/8
ap12231c-1-2.jpg


Rheem SP12231B Overall Length (in.): 3-3/4
sp12231b-2.jpg
 
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Thanks for the reply. Yes I believe the drain valve is the same or very similar to the picture you show.

I just am concerned if whether or not this is code approved should I ever sell the house.

I keep looking at the diagram to see if a check valve should be added between the new drain valve and outlet of the primary side of the heat exchanger. I don’t see a reason to since the pump has a check in it. Thoughts?
 

Reach4

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I keep looking at the diagram to see if a check valve should be added between the new drain valve and outlet of the primary side of the heat exchanger. I don’t see a reason to since the pump has a check in it. Thoughts?
With one in the pump, no added check valve should be needed.
 

Sylvan

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Looking at your drawing I would say no because the T&P has to be in the upper most 6" of the tank and you have a fitting (TEE) then the T&P on the run of the tee so the probe will not be immersed properly

As one vet to another thank you for your service
 

wwhitney

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Looking at your drawing I would say no because the T&P has to be in the upper most 6" of the tank and you have a fitting (TEE) then the T&P on the run of the tee so the probe will not be immersed properly
Are T&P valves with extra long probes available, and would that take care of the issue?

Cheers, Wayne
 

Sylvan

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Are T&P valves with extra long probes available, and would that take care of the issue?

Cheers, Wayne
Not really as the probe does collect mineral deposits that hinder the probe from sensing the actual temperature.

Pressure is no problem

Nipple and Tee and then the probe maybe excessive
 

jadnashua

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Why not put a T in the hot outlet versus the T&P port?

Some tanks have an extra port that just has a plug in it so look the tank over for maybe a plastic cap on the outer shell. On some, they may have an optional, second anode, and that may just be plugged, but available.
 
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Looking at your drawing I would say no because the T&P has to be in the upper most 6" of the tank and you have a fitting (TEE) then the T&P on the run of the tee so the probe will not be immersed properly

As one vet to another thank you for your service
Thanks for your service as well buddy
 
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Why not put a T in the hot outlet versus the T&P port?

Some tanks have an extra port that just has a plug in it so look the tank over for maybe a plastic cap on the outer shell. On some, they may have an optional, second anode, and that may just be plugged, but available.
That’s what I was thinking as well, put a T in the hot water outlet. Just wasn’t sure if it was “legal” to pipe the return into where the existing tank drain valve is.
 
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