T&p discharge on 2.5 gallon under sink

[Gommer]

I know what you are supposed to do, but can't seem to find any info on how. I've even watched a few how-to videos and they don't address it either. If I install a small point of use water heater tank under the kitchen sink, how and where do I send the t&p discharge if there is no way to send it outside and there is no floor drain? I wouldn't even be able to get the proper down pitch if I routed it to the waste pipe from sink

The how-to video's I watched don't even install a pipe on the t&p. Do people just ignore this given the lack of options to do it properly?

 

[KULTULZ]

The valve must be plumbed as on a tank water heater. It must terminate 6" above the sink cabinet floor. A receptacle can catch the overflow to protect the cabinet.

I would think one could devise a drain if he wanted to go to the trouble, but would still have to employ an air gap (unless plumbed to outside drain and then you have to take into consideration freezing temperatures).

What model do you have?

 

[phishfood]

IPC code does not require that the T&P valve be piped to a drain, just that the discharge not pose a hazard. It does, however, require that a water heater in a living space have a pan under it piped to a drain.

 

[KULTULZ]

IPC code does not require that the T&P valve be piped to a drain, just that the discharge not pose a hazard. It does, however, require that a water heater in a living space have a pan under it piped to a drain.

Forgot that little diddy...

That's a tanked WH, right...

A tankless make more sense?

 

[Gommer]

Yes, this is a tank. I have the tankless for household use, but the kitchen sink is at the end of the line. I'm on a slab and everything was ran in series ending at the kitchen sink. Takes approx 8 minutes of running water to get warm water at sink. Wanted to throw a tank under sink to help out. I just can't seem to find a way to meet code! There is no drain, therefore I can't point t&p discharge towards it nor the drip pan. I guess I will just have to roll the dice that absolutely nothing will go wrong and stick it under there or go without hot water in kitchen. Very frustrating.

Thanks for the comments.

 

[KULTULZ]

At the least, have the discharge of the TPRV pointing away from the cabinet opening so that no one will get blasted during a discharge while looking for something in the sink cabinet.

This is a perplexing problem and am wondering why it hasn't been addressed in code...

I was thinking a drain pan using a condensate pump but the pump wouldn't be rated for hot water. If the unit can be mounted high enough off the cabinet floor, possibly a receptacle with a separate drain line from it into the DWV (similar to an WH drain to the outside allowing for freezing temp)?

You have already purchased the tank model, correct?

 

[Gommer]

Yes, very perplexing problem. My kitchen sink is in center of home on island, no outside wall and I'm on slab. Of all the research I've done, nothing addresses this issue. Using a point of use water heater is a common suggestion for under sink, you'd think this would be a common problem for many. I have a hard time imagining that majority of kitchens have floor drains that permit this type of install.

Yes, I was given the small tank as a gift from family because of our complaining of no hot water in kitchen.

 

[KULTULZ]

I found these two pages of code (don't know if current) ...

The TPRV must have some type of drain and that dedicated drain cannot be routed to the WH drain pan.

Also, when you go to manufacturer install manuals, thermal expansion is brought up possibly requiring it's own thermal expansion tank for safety.

And the manual also mentions needing/having an emergency cut-off switch if the WH is out of sight of the main breaker box (much like new NEC for a DW install).

In short, plumbing a POU WH is much alike plumbing a whole house tank WH (ill shown below).

 

[Gommer]

Yup, that's what all the info was telling me and why I came on here to see how it's really done. I know how popular pou wh are for under sink applications and probably none of them have floor drains, etc. So I'm assuming this is the area where people say to Hell with doing it righ tand just install it and move on? That's what they've done in the coke how-to video's I watched. They didn't even put a pipe on outlet of t&p, just hooked up inlet and outlet, slid it under sink..job done.

 

[phishfood]

A recirculation pump might be a better solution to your problem.

 

[stevemachine]

A recirculation pump might be a better solution to your problem.

I would tend to agree.