Overflow pan drain

[ksftx]

My water heater is in a closet with a raised floor. The pressure release discharge line is copper tube that runs down the wall, under the floor, and through an outside wall. My current heater, without an overflow pan, will need to be replaced soon. Is it possible (allowable - Richardson, TX) to tie the overflow pan discharge into this existing T&P discharge line? It would tie in along the horizontal run of the existing line under the closet floor.

 

[Fitter30]

No if the relief valve would fail at full flow the drain pipe wouldn't handle that flow and spray out the drain pan.

 

[Sponsor]

 

[Jeff H Young]

IPC plumbing code specificaly allows a t and p to dump into the drain pan 504.6 explains it clearly

 

[Tuttles Revenge]

IPC plumbing code specificaly allows a t and p to dump into the drain pan 504.6 explains it clearly

And on the next line also states that where it discharges must not cause structural damage. And a pan would need a rather large drain in order not to overflow. I have installed water heater pans that were basically shower pans with 2" traps under them.

I think that Fitter is correct in that if the pan were connected to the relief drain in such a way as to allow water at full flow to come back to the pan and overflow it, would cause damage. It likely could be plumbed in such a way that the full discharge of the T&P would exit the building as its plumbed now but also not back up into and flood the pan. Usually a drop from the pan and tee on a vertical from the T&P drain would accomplish this. But I'm also not certain that the 2 drains could be tied together.

 

[ksftx]

This was my first post and I'm amazed by the prompt and informative replies. When inspecting further, I discovered the T&P line has at least a 6" vertical rise in the outside wall before the exit outside. Probably fine for a release under pressure, but not for a drip pan discharge. I should dug further initially, just trying not to have to poke another hole through the brick mortar, but looks to be unavoidable. Thanks so much for the responses!

Since this will essentially be an open line from the drip pan to the exterior, is there something that can be added to prevent entry by pests?

 

[Jeff H Young]

And on the next line also states that where it discharges must not cause structural damage. And a pan would need a rather large drain in order not to overflow. I have installed water heater pans that were basically shower pans with 2" traps under them.

I think that Fitter is correct in that if the pan were connected to the relief drain in such a way as to allow water at full flow to come back to the pan and overflow it, would cause damage. It likely could be plumbed in such a way that the full discharge of the T&P would exit the building as its plumbed now but also not back up into and flood the pan. Usually a drop from the pan and tee on a vertical from the T&P drain would accomplish this. But I'm also not certain that the 2 drains could be tied together.

The code is clear IPC allows a tand p to drain to the pan . I think IPC code sucks in many ways . Im not aprooving of the practice His question asked if it was allowable in Richardson TX . my answer is Yes , and You guys say No you cant I dont recomend half the crap in that code . 504.7.2 says he dosent even need a pan what kinda crap is that " where a Pan iwas not previously installed, a drain pan need not be installed " so while I think pans are a good idea Im not telling him he must install a pan either

 

[Tuttles Revenge]

I think tying the pan into the t&p drain after the pan drain drops and connects to the horizontal of the t&p will work fine and not allow any back pressure from the t&p to come back into the pan and potentially flood out.

504 says that the pan can be a reciever of the t&p as long as it doesn't create a dangerous situation or cause structural harm if it overflows. Totally gray area where interpretations can vary.

We install pans under water heaters all the time, but almost never run a drain from them. Instead we install alarms. Water heaters rarely initially leak a LOT of water. Most of the time its a slow leak. With a pan and a drain, a person may not catch the problem until it becomes catastrophic. An alarm lets you know right away that you have water leaking.

 

[Jeff H Young]

I think tying the pan into the t&p drain after the pan drain drops and connects to the horizontal of the t&p will work fine and not allow any back pressure from the t&p to come back into the pan and potentially flood out.

504 says that the pan can be a reciever of the t&p as long as it doesn't create a dangerous situation or cause structural harm if it overflows. Totally gray area where interpretations can vary.

We install pans under water heaters all the time, but almost never run a drain from them. Instead we install alarms. Water heaters rarely initially leak a LOT of water. Most of the time its a slow leak. With a pan and a drain, a person may not catch the problem until it becomes catastrophic. An alarm lets you know right away that you have water leaking.

Yea there is a lot to this the drain location has to be observable but that could be on side of house and we might not go there for weeks
I like your method of an alarm too , but would expect capping off the drain could be an issue its a great idea where the pan is such a hardship to drain properly . but our code inspector could call us out I belive and bust our balls saying the pan is installed improperly (no drain).
another issue is a slow leak even if a dumb owner knows about it if its safely draining its ignored especially renters