I don't want my WH T&P to vent in the room, but code says it has to?

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Arizona CJ

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I do not want my water heater T&P to vent in the room, but the code says it has to. (?!)

I’m thinking of replacing a Bradford White 50 gal gas water heater, which has been in service since 1993 (though oddly has a manufacture date of 1991). The home was built in ’93. The water heater is in the furnace room at the back of a slab floor walk-out finished basement. It does not have a pan, so I am concerned it may fail and leak.

I do not approve of the current setup, and want to replace it with a SAFE and reliable one. I intend to add a drip pan with a sump pump and an auto-shutoff. (It already has an expansion tank, I put that in a few years ago).

Sounds easy, right? I thought so until I cracked open the city code book (replacement water heaters are supposed to meet current code here, and get inspected.). Here, in a nutshell, is the objectionable code section I ran into, and three visits to the city plus talking to two plumbers have not resolved;

2. Discharge through an air gap located in the same
room as the water heater.

Currently, the water heater T&P discharge line is a properly sloped and sized 40mm copper line to the outside of the building. The two plumbers tell me this is the best way to do it. But the city code says put an air gap INSIDE the furnace room! And, to make it even stranger, both plumbers said they were unaware of this item in the code. But I guess that’s okay, because so were the people I spoke to at the city permitting department (who had given me the code by copying their book!). They did confirm it applies, but had never heard of it. Great.

I consider terminating the T&P line inside the furnace room unacceptable for safety and damage reasons (anyone who has seen one do a full release understands why), especially when a perfectly good T&P line to outside is already there. Further, there is no floor drain, nor any way of adding one (And I wouldn’t terminate it there anyway; that furnace room is the walkway to a workshop so IMHO it’s a big safety risk that’s unneeded). I saw a T&P valve release from a water heater when I was a kid (burner stuck on) and it was quite violent, hence my concerns.

The city said the inspector would “probably” okay using the existing external line if it meets the manufacturer’s install instructions. But, the install instructions I’ve found so far show only the straight-down-the-side-to-over-a-drain method. I don’t like “probably” when I have to do all the work and expense first, and I won’t accept venting into the room unless there’s a real (as opposed to simply code) reason.

Also, items 5 and 6 of the code seem to contradict item 2:

5. Discharge to the floor, to the pan serving the
water heater or storage tank, to a waste receptor
or to the outdoors.

6. Discharge in a manner that does not cause personal
injury or structural damage.

Item 5 lists “to the outdoors” as an option, but appears predicated on an air gap in the room per item 2.
Item 6 is, in this location, exactly what I am trying to avoid by refusing to have an air gap in the room.

So I need to ask; is there any reason, other than code, why using the existing external-venting T&P line, with no air gap in the room, isn’t the safer option given the location and circumstances? If I’m forced to choose between obeying the code and safety, I’ll choose safety. Any thoughts or information would be greatly appreciated.


Thanks, from a very confused Arizonan, CJ.
(BTW, though I’m newly registered, I love this forum, I’ve been binge reading the threads.)
 

Terry

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A T&P on a water heater discharges about six inches above ground. That gives you the air gap needed and also for safety reasons prevents scalding someone. I think getting your toes wet is okay.
Normally this discharge outside in a visible place. Not concealed in a crawl space. Of if inside, daylighting them above a floor drain works. Some homes don't have the floor drain, and where the line can't drain to a floor drain, or gravity drain to the outside, they sometimes run them down and place a small bucket to catch any drips.
In extreme cases, I have installed a 125 PSI relief valve on the cold and run that outside by gravity. I stall use the T&P on the water heater when I do that. The idea being that the lower pressure kicks off on the cold before the one on the water heater releases. You always want a working T&P on the water heater.
There was a water heater in the Seattle area where someone had plugged the T&P. It rocketed through the roof and landed a block away in the street.
 

Arizona CJ

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Thank you for your reply, Terry! (and thank you for this wonderful site, too!)

To be clear, I absolutely do want the best possible T&P system. I just want it to discharge outside, not in the room. There is no drain in the room, no way to put one in, and it is a finished basement, so even if safety wasn't a concern, I would not want the discharge in the room (all that water would do a lot of damage, including ruining the furnace).

You said "Normally this discharges outside in a visible place". This is what I *want* to do, and the current plumbing already *does*. My issue is that the code seems to demand otherwise, hence why I'm thinking of skipping the code and inspection and just using the existing outside discharge.

Edit to add; in another thread, you said, "My preference is to always pipe the T&P outside." That's what I want to do (It's already in place from the old WH)) so unless there's some reason not to use it, I'll do it that way, and ignore item # 2 of the code (from my original post).
 
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Reach4

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Arizona CJ

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What code? I think AZ starts with IPC and/or UPC, and then amends.

You will like this link:
See http://www.waterheaters-phoenix.com/phoenix-water-heater-codes/

Of course AZ is a big state. Different areas can have different requirements. I expect what people do for the discharge in Gilbert will differ from what they do in Flagstaff.

This is a city code (they xeroxed it out of the city code book for me, and it matches what's online for the city) which includes requiring a permit and inspection for replacement of water heaters (and payment of a large fee). However, the offending item # 2 of the code appears to originate, word for word, item number included, from the 2006 IRC P2303.6.1 ; and also IPC 504.6 ;
2. Discharge through an air gap located in the same room as the water heater.

Here's a link to a brief code discussion by building inspectors, stating that there *has to be an air gap in the same room as the water heater* even if it's an outside discharge. https://www.nachi.org/forum/f22/discharge-question-25085/

But, contra this, every plumber I've spoken to so far much prefers direct exterior discharge (and that's before I mention that the direct exterior discharge line I want to use already exists.)

Today I inspected the existing T&P line (to the outside) for its entire length, including checking the slope (downhill all the way). It looks great, 3/4" copper, just two elbows total (one is the termination elbow on the building exterior) and the term elbow is plainly visible, and the line is about 23 feet overall length. I think I'd be flat out nuts not to use it, but this code issue is worrying the heck out of me (and I'm now on attempt #5 to get a definitive answer out of the city permits office, no joy.).

Do I seriously have to choose between the best safety (direct exterior vent) and obeying the code and permitting requirement? If so, I'll be choosing safety.
 

FullySprinklered

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Local codes are not dictated by Almighty God. They are more often dreamed up by ex-plumbers who can't cut it in the field , who work for the government to get the free health insurance because their wife made them do it and they are glad because they don't know what the f*** they're doing anyway.
 

Arizona CJ

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Here's another issue; the T&P valves I'm seeing release at 212 degrees. The boiling point of water here is about 199 degrees (due to altitude). So, if the T&P opens, you're going to get a release of over 8000 BTU just to get the water down to boiling, plus every gallon that comes out from a 75 gallon tank will release (and that doesn't count the BTU of the hot water that comes out too). That';s a lot of energy and steam to blast into a small room (for comparison, that's often human-occupied, yet code says it's okay to discharge into a bucket or drain beside the water heater. I consider that madness.

Roughly, one BTU equates to the energy released by burning a single wood phosphorous match. So, who wants to be in a tiny room with 8000 of those going off in seconds, plus a thousand more for every gallon of water that comes out?

No way, no how, am I going to allow that thing to discharge inside the room (where there is no drain an no way to add one). Outside the building has gotta be safer.
 

Sylvan

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"No way, no how, am I going to allow that thing to discharge inside the room (where there is no drain an no way to add one). Outside the building has gotta be safer."

Sure is safer UNTIL some child or animal happens to be there when the T&P discharges then the after the lawsuit you will find you're totally liable
 

hj

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Those same children or pets could be near the discharge opening REGARDLESS of where it is located. I am not sure which city you are in, but our inspectors almost INSIST that it be piped to the exterior of the building.
 

Sylvan

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Those same children or pets could be near the discharge opening REGARDLESS of where it is located. I am not sure which city you are in, but our inspectors almost INSIST that it be piped to the exterior of the building.

NYC very populated area where no one takes personal responsibility

Read about the two children killed in Hunts point and draw your on conclusions after reading everything out there about "radiator exploding"

The newest case I am working on is a child severely burned by an exposed heating line (hydronics)
 

LLigetfa

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There was a thread a while back where the T&P was terminated through the floor into a crawlspace and the tenant was unaware of it discharging. All of the subflooring and flooring through the entire house buckled due to the high moisture and needed to be replaced.

Size and route the drain in such a way that it can handle the volume of flow from a full open discharge.
 

Arizona CJ

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@Sylvan; The existing T&P relief line to the exterior of the building terminates a couple of feet over a rocky mountainside, well away from any walkway, and well over a hundred feet from the nearest property line or public street. The chances of anyone being in that location are basically zero. The chances of someone being in the room with the water heater are massively higher. Plus, use some common sense here; if it's safe to terminate the line inside the room 6" from the floor in a walkway area, how on earth is it less safe to terminate it the same outside on a steep rocky slope, well away from a human-trafficked area? And as for hypothetical liability, are you serious? Even if that was real, I'm vastly more interested in protecting the actual safety of my family and also myself.

@ LLigetfa; The water heater is located in the back of a finished walk-out basement. It's a slab floor. There is NO WAY to run a floor drain (this is existing construction). If there was, I'd do it, but there isn't. Terminating in a bucket beside the water heater would be legal here in these circumstances, but it's not acceptable to me on safety grounds (Plus I'm not keen on flooding my furnace room and finished basement with boiling water). The building exterior T&P vent line just seems much better, plus the vent line is already there, in 3/4 copper, in great condition, and downhill all the way. The only difficulty (aside from the possible code issue I listed upthread) will be finding a WH with the T&P on top (Side vent is too low for the T&P line), and if I can't, I'll either have to put a long-shank one in a T on the hot side outlet, or build a platform to raise the heater and also redo the flue ducting a bit.
 

Jadnashua

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Run the output via an air gap to a drain that then runs outside. That gap doesn't need to be big and it doesn't need to be a floor drain. You should be able to do this high enough to go outside via gravity. If the diameter of the outlet is big enough, you might get some steam if it discharged from overheating, but if the line was large enough, it wouldn't overflow. Discharging through the air gap doesn't mean you have to dump it on the floor.

A far more common fault of a WH is that the tank springs a leak. Without a pan and a drain, that is the more likely source of water damage. The next more common thing is if your expansion tank fails and the pressure is released. A stuck burner causing it to overheat is probably the least likely scenario for a leak and definitely not common. FWIW, that's what insurance is for.
 

Arizona CJ

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Run the output via an air gap to a drain that then runs outside. That gap doesn't need to be big and it doesn't need to be a floor drain. You should be able to do this high enough to go outside via gravity. If the diameter of the outlet is big enough, you might get some steam if it discharged from overheating, but if the line was large enough, it wouldn't overflow. Discharging through the air gap doesn't mean you have to dump it on the floor.

A far more common fault of a WH is that the tank springs a leak. Without a pan and a drain, that is the more likely source of water damage. The next more common thing is if your expansion tank fails and the pressure is released. A stuck burner causing it to overheat is probably the least likely scenario for a leak and definitely not common. FWIW, that's what insurance is for.

I cannot put in a drain. It's a slab floor walk out finished basement, and the walk out side (where the drain would need to head for) is on the far side from the WH. There is no way to run a drain without trenching the slab all through the finished rooms (Even a wall run won't work; there's a doorway in the way and I've have to rip apart lots of wall). There is a bathroom in the basement, but it's on the far side from the WH. So, I still think using the existing exterior-vent relief line is the safest option.

Totally agreed on the leak issue! My plan on that is a drip pan with a dual automatic shutoff in it (cuts off water and gas if it gets wet) plus a pump in the pan (there's a work sink in the room above). I would of course prefer having a drain in the room with the WH, but with no way to put one in, this is the best I can come up with, so far.

Thanks!
CJ :)
 

LLigetfa

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The building exterior T&P vent line just seems much better, plus the vent line is already there, in 3/4 copper, in great condition, and downhill all the way.
Could you not replace that 3/4" line with a larger one that can handle the volume of flow with an air gap at the tank?
 

Arizona CJ

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Could you not replace that 3/4" line with a larger one that can handle the volume of flow with an air gap at the tank?

About a 3"? I could, but it'd have to be about the same height as the existing T&P line (otherwise it means tunneling through the foundation). So, that'd mean raising the WH by a lot to accommodate the air gap drop, and the air gap would have to be at roughly eye level. I guess I could put that behind the tank to avoid splash, but this still seems slightly less safe than exterior direct vent? I'd be willing to undergo this work and expense if there's a safety reason to do this (And if there is, please let me know). But that's my point; I can't see an actual *reason* (aside from a possible code technicality) to have an air gap inside the room, plus that seems like an unwarranted safety risk (especially due to needing it, in my case, so high).
 

Terry

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I would ask the local inspector what they expect on existing homes. Don't tell them who you are, just ask what they expect when the home was plumbed and inspected years ago and passed code at that time. It would be pretty brutal to expect everyone to replumb their homes every time a code changes.
 

Jadnashua

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Some things will end up being grandfathered, but often, when you make changes, those changes need to be done to code.
 

Arizona CJ

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I would ask the local inspector what they expect on existing homes. Don't tell them who you are, just ask what they expect when the home was plumbed and inspected years ago and passed code at that time. It would be pretty brutal to expect everyone to replumb their homes every time a code changes.

I'm trying. :) the problem is that in order to arrange it, I'd have to leave my name and number. So, I'm trying to catch one at the permit office. No luck so far, but I'll keep trying (I've been advised that early mornings is best, so I'm trying that as of tomorrow). I figure I'll see one eventually, and I aim to keep trying.

I'm also going to be asking plumbers (all of whom recommend doing the T&P line exactly as I propose) if they will guarantee they could get this passed. If so, they're getting hired for the job, plus get the sale of the new WH.

If I have to replumb (within reason - blasting trenches in the slab is out) I will, if (and only if) the result is at least as safe as the current setup. I'd also want to replumb if doing so would make it actually safer.

Some things will end up being grandfathered, but often, when you make changes, those changes need to be done to code.

I'm very willing to make changes if required by code, but if, and only if, those changes don't make things less safe.

Saving money isn't my motive in this; I could meet code by simply dumping the T&P into the drip pan if the drip pan has a sump pump and alarm, and it's going to have those anyway. But that arrangement in a small human-trafficked room isn't safe IMHO, so I won't consider it.

I'd even be ok with spending some time and money to attain the same safety as the original plus meet the new codes, but not less safety, no way. That'd be insane when the purpose of the code is safety.
 

FullySprinklered

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In my area, more often than not, the t&p discharge line has to go up in order to exit the house. Forget the air gap, forget gravity. Just put a drain cock of some sort on the line to bleed off any water that might end up in the line for whatever reason. The discharge terminates 6" above the dirt once you exit the house, as Terry indicated. You worry too much. It's all been worked out.
 
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