Thread: Elbows in T & P drain pipe

Can anyone tell me if there is a limit to how many elbows can be in a hot water tank T&P drain pipe. I seem to recall that there is definitely a limit but I can not find the answer.
Thanks
Greg

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4 elbows maximum.

30 feet long maximum, all down hill.

It's right on the tag. (It's also on the Watts website where the T&P valves are, at least it was years ago.)

Thanks Jerry.
Is that 4 - 90's or any elbow?

Originally Posted by Greg Jenkins

Is that 4 - 90's or any elbow?

It says 'four elbows', does not specify whether 90 or 45 - either would disrupt the flow to some extent and create a bit of back pressure, back pressure is one thing they do not want - get the water out and get it out fast.

Ok, we'll go with four of any elbows for now but I know I have read specific documentation on this subject before I just cann't seem to locate it. If any one else knows the specifics, please chime in. On this mornings inspection the pipe had three 90's and a 45 then they shot it straight thru the wall to the exterior but did not point it toward the ground. It also was not protected from freezing (but that's another issue).

Jerry
4 elbows: you got a code section # for that or is it only mafg inst. instructions?

Originally Posted by Jerry McCarthy

Jerry
4 elbows: you got a code section # for that or is it only mafg inst. instructions?

Manufacturer's installation instructions, but ... since Greg's last post above I've off and on been trying to find it on the Watt's web site, however, it seems they are changed all the requirements now that the codes say that the T&P relief valve discharge line must terminate in the same room as the water heater is.

Attached is an older one, but I can no longer find that valve on Watts' web site.

Thus, on houses 'before' the newer codes (since 2000-2003) came into affect, the 30 feet and not more than four elbows was the rule (Watts' rule).

However, on newer homes, the 'shall terminate in the same room as the water heater is' is the rule (code).

Here ya' go:

Watts Water Safety and Flow Control Products - balancing valve, ball valve, butterfly valve, check valve, relief valve, temperature gauge

Originally Posted by Michael Thomas

Here ya' go:

Watts Water Safety and Flow Control Products - balancing valve, ball valve, butterfly valve, check valve, relief valve, temperature gauge

I must of read that page 10 times last night and missed that 30' / 4 elbows part in there every time.

Glad to see it is still in there.

Originally Posted by Michael Thomas

Here ya' go:

Watts Water Safety and Flow Control Products - balancing valve, ball valve, butterfly valve, check valve, relief valve, temperature gauge

Interesting.... Under "REINSPECTION OF T&P RELIEF VALVES" it says you should pull the TPR valve once every three years and inspect it. I never knew that. Learn something new everyday.

Jeff Euriech
Peoria Arizona

Jeff,

Inspect every 3 years? Yeah, that's going to happen.

I just remember it by doing it after every 36th time I test all of the my GFI's.... Is there an easier way?

Hi all,
first post and all but thought I would jump into the fray on this one. The 2003 IRC doesn't say anything about the drain "having" to terminate in the same room and the 2006 is no different. I know in my neck of the woods I rarely see it terminate indoors unless it is very difficult to get it to the outside.
From the IRC: "P2803.6.1 Requirements of discharge pipe.
The outlet of a pressure relief valve, temperature relief valve or combination thereof, shall not be directly connected to the drainage system. The discharge from the relief valve shall be piped full size separately to the floor, to the outside of the building or to an indirect waste receptor located inside the building. In areas subject to freezing, the relief valve shall discharge through an air gap into an indirect waste receptor located within a heated space, or by other approved means. The discharge shall be installed in a manner that does not cause personal injury or property damage and that is readily observable by the building occupants. The discharge from a relief valve shall not be trapped. The diameter of the discharge piping shall not be less than the diameter of the relief valve outlet. The discharge pipe shall be installed so as to drain by gravity flow and shall terminate atmospherically not more than 6 inches (152 mm) above the floor. The outlet end of the discharge pipe shall not have a valve installed." Perhaps UPC areas say something different?

2006 IRC
P2803.6.1 Requirements for discharge pipe.

The discharge
piping serving a pressure-relief valve, temperaturerelief
valve or combination valve shall:
1. Not be directly connected to the drainage system.
2. Discharge through an air gap located in the same
room as the water heater.
3. Not be smaller than the diameter of the outlet of the
valve served and shall discharge full size to the air
gap.
4. Serve a single relief device and shall not connect to
piping serving any other relief device or equipment.
5. Discharge to the floor, to an indirect waste receptor
or to the outdoors. Where discharging to the outdoors
in areas subject to freezing, discharge piping
shall be first piped to an indirect waste receptor
through an air gap located in a conditioned area.
6. Discharge in a manner that does not cause personal
injury or structural damage.
7. Discharge to a termination point that is readily
observable by the building occupants.
8. Not be trapped.
9. Be installed to flow by gravity.
10. Not terminate more than 6 inches (152 mm) above
the floor or waste receptor.
11. Not have a threaded connection at the end of the piping.
12. Not have valves or tee fittings.
13. Be constructed of those materials listed in Section
P2904.5 or materials tested, rated and approved for
such use in accordance with ASME A112.4.1.

Richard, there is also #5 in the 2006.

5. Discharge to the floor, to an indirect waste receptor
or to the outdoors. Where discharging to the outdoors
in areas subject to freezing, discharge piping
shall be first piped to an indirect waste receptor
through an air gap located in a conditioned area.

#5 is applicable to the drain pan under the WH.

#5 is applicable to the drain pan under the WH.

Where does it say that? The way I read it, all 13 items apply to the "discharge piping." No?

Originally Posted by charles buell

Richard, there is also #5 in the 2006.

5. Discharge to the floor, to an indirect waste receptor
or to the outdoors. Where discharging to the outdoors
in areas subject to freezing, discharge piping
shall be first piped to an indirect waste receptor
through an air gap located in a conditioned area.

Charles,

#5 is referring to where the discharge from the air gap can discharge to.

FIRST do #2, THEN you have to drain that 'somewhere' and #5 tells you where you are allowed to drain that to.

Jerry, I see the "list" as what can and can not be done---I just don't see any if-then to the list. What you are saying may be what was "intended" by the change from 2003---but it is not what it says. I expect we will be seeing more clarification on this one. Like I said previously, I am not seeing any terminations on the interior of the home unless there is no other way to do it---of course not very many jurisdictions have adopted the 2006IRC in my area----none that I know of.

Originally Posted by charles buell

Jerry, I see the "list" as what can and can not be done---I just don't see any if-then to the list.

Charles,

Maybe it will help if I post it this way:

- 2006 IRC
- - P2803.6.1 Requirements for discharge pipe. (Jerry's note: The following *are* *requirements* for the relief valve discharge pipe.)

- - - The discharge piping serving a pressure-relief valve, temperature relief valve or combination valve shall: (Jerry's note: "Shall" have, i.e., the following are "shall" requirements except where given as options.)
- - - - 1. Not be directly connected to the drainage system. (Jerry's note: The discharge line "shall" not be directly connected to the drainage system - this is a "shall" requirement.)
- - - - 2. Discharge through an air gap located in the same room as the water heater. (Jerry's note: The discharge line "shall" discharge "through an air gap" - that is a "shall", not an option - "located in the same room - that is a "shall", not an option - these are "shall" requirements.)
- - - - 3. Not be smaller than the diameter of the outlet of the valve served and shall discharge full size to the air gap. (Jerry's note: The discharge line "shall" not be smaller than the diameter of the valve outlet - this is a "shall" requirement.)
- - - - 4. Serve a single relief device and shall not connect to piping serving any other relief device or equipment. (Jerry's note: The discharge line "shall not" be connected to any other piping - this is a "shall" requirement in the negative, i.e., "shall not".)
- - - - 5. Discharge to the floor, to an indirect waste receptor or to the outdoors. Where discharging to the outdoors in areas subject to freezing, discharge piping shall be first piped to an indirect waste receptor through an air gap located in a conditioned area.(Jerry's note: These are discharge line 'options', i.e., this gives you choices on where the discharging water is allowed to discharge - this is a "shall" requirement with several 'options' to the "shall".)
- - - - 6. Discharge in a manner that does not cause personal injury or structural damage. (Jerry's note: The discharge line "shall" discharge in a manner in which the discharge does not cause personal injury or structural damage - this is a "shall" requirement stating a negative in a positive manner, i.e., you "shall not" discharge to - for example - the interior wall space as that could cause structural damage, or, you "shall not" discharge at a height and location which could discharge directly into the face of a person as this could cause personal injury, i.e., - this is a "shall not" requirement.)
- - - - 7. Discharge to a termination point that is readily observable by the building occupants. (Jerry's note: The discharge line "shall" discharge where discharging water is readily visible to the occupants, i.e, - this is a "shall" requirement.)
- - - - 8. Not be trapped. (Jerry's note: The discharge line "shall" not be trapped - this is a "shall not" requirement.)
- - - - 9. Be installed to flow by gravity. (Jerry's note: The discharge line "shall" be sloped to drain by gravity, i.e., the same as "shall not" be trapped, if trapped, it will not drain by gravity - this is a "shall" requirement.)
- - - - 10. Not terminate more than 6 inches (152 mm) above the floor or waste receptor. (Jerry's note: The discharge line "shall not" be more than 6" high above the floor or waste receptor as that could lead to splashing and spraying and could cause personal injury or structural damage - see 6. above - this is a "shall not" requirement.)
- - - - 11. Not have a threaded connection at the end of the piping. (Jerry's note: The discharge line "shall not" have a threaded end - this is a "shall not" requirement.)
- - - - 12. Not have valves or tee fittings. (Jerry's note: The discharge line "shall not" have valves or tee fittings - this is a "shall not" requirement.)
- - - - 13. Be constructed of those materials listed in Section P2904.5 or materials tested, rated and approved for such use in accordance with ASME A112.4.1. (Jerry's note: The discharge line "shall" be constructed of approved material - this is a "shall" requirement.)

You have now been advised how the T&P relief valve discharge line "shall" be installed, and what you "shall not" be allowed to do, with some 'options' on how to accomplish the "shall" part in some cases.

It *does not* say you "shall do #2 *unless* you do #5", it states you "shall do #2" and it also states that you "shall do one of the options in #5" also.

Did this help?

I am sorry Jerry but I must be a little dense. I just don't see how we can have #2 and one of #5 at the same time.

One way
1. Drain the TP to (air gap -1-2") just above -the pan, which is considered a waste receptor.
2. Drain the pan to the floor to a (another) waste receptor or to the exterior.

Another way
Drain the TP to air gap just above a floor drain (same room - visible) (waste receptor) It still needs a pan w/drain.

Originally Posted by charles buell

I just don't see how we can have #2 and one of #5 at the same time.

Not to worry, sometimes I am dense too and it takes a 2x4 upside the head for me to understand what is being said.

Originally Posted by Richard Stanley

One way
1. Drain the TP to (air gap -1-2") just above -the pan, which is considered a waste receptor.
2. Drain the pan to the floor to a (another) waste receptor or to the exterior.

Another way
Drain the TP to air gap just above a floor drain (same room - visible) (waste receptor) It still needs a pan w/drain.

As Richard stated:

- must discharge in same room (2. Discharge through an air gap located in the same room as the water heater.) AND that discharge may discharge to floor (5. Discharge to the floor, ... ) - the "air gap" in #2 is the space between the end of the discharge pipe and the floor.

- must discharge to same room (2. Discharge through an air gap located in the same room as the water heater.) AND may that discharge may discharge to an indirect waste receptor (5. Discharge to ... an indirect waste receptor ... ) - the "indirect waste receptor requires an air gap between it and the pipe discharging into it, i.e., the "air gap" in #2 is at the "indirect waster receptor" in #5, which is then discharged to (floor, floor drain, outside).

- must discharge to same room (2. Discharge through an air gap located in the same room as the water heater.) AND may that discharge may discharge to outdoors (5. Discharge to ... the outdoors. Where discharging to the outdoors in areas subject to freezing, discharge piping shall be first piped to an indirect waste receptor through an air gap located in a conditioned area.) - the "air gap" in #2 has to discharge someplace, the water is just not going to disappear into thin air, thus, that water may drain to the "outdoors" in #5, provided provisions are made to keep any discharge from freezing.

Does that help?

OK guys----I get what you are saying----I just disagree. I hope we can agree to disagree. So are you operating under the 2006 IRC? This whole conversation is a moot point if you are under the 2003. Yes? One thing I just don't get is how you are seeing #5 as being so specifically related to the pan? Maybe it "should" or was "intended" but I just don't see it there. I once had a city inspector tell me that the Code is not: what you think it says, what you wish it said, what you hope it says, what you have heard it says, what you need it to say----it is just the code.

If this indirect receptor installation becomes the standard type of installation I see more potential problems with it than it cures and some additional wording or clarification is going to be necessary. Perhaps properly functioning TPR valves will always release pressure in drips and spurts, but can they still discharge with tremendous force? If so, then properly restraining the end of the pipe so that it doesn't kick back is going need to be addressed. I also think that such a blast would blow back out of the receptor when it hit the water in the trap.

I would also add that #8 says that the drain can not be trapped and is on the list "after" the air gap requirement indicating that there shouldn't be a trap anywhere in the line----before or after. No?

Perhaps we can agree that 2006 is not making anything any clearer.

Right. #8 - no traps.. Why would you need one? No sewer gas involved.
If a floor drain is used, it would have its own trap - probably.

Could you get an initial pressure burst if the valve opened because of high pressure? Yes. Is it going to spash someone? Probably. The pressure will rapidly diminish after the initial burst. Could it cause injury to someone standing near the TP termination point? Possibly. Is it possibe to protect everyone from every possible eventuality? I doubt it.

Personally, I liked the idea of having the TP go to the exterior. I don't know what the thinking was that caused the change. Maybe because occupants couldn't see it buried in the bushes. I suspect they would get a clue something was amiss when they got a cold shower.

What are the odds that the TP would ever activate anyway? But it could! Which is what we're talking about.

If you can conceive another method of the drainage that would meet all the '06 criteria, I would like to here/see it.
Tankless??

Livin' the dream.

"Tankless?"

Tankless units have pressure relief valves.

Gas tankless units have pressure relief valves. PRV
Electric units - TP valve not required by mfg. - may be required by AHJ.
I have not read the requirements for all of the brands - but, this seems to be common.

Another thing - some (gas) allow the exhaust pipe to have a descending slope in the direction of termination. The units have a blower.
Also, B vent pipe not allowed - except in certain situations where it is used as a sleeve with the solid vent pipe inside of it.

Originally Posted by Richard Stanley

Gas tankless units have pressure relief valves. PRV
Electric units - TP valve not required by mfg. - may be required by AHJ.
I have not read the requirements for all of the brands - but, this seems to be common.

Richard,

From the 2006 IRC (but it's been this way since I can remember - bold is mine).
- SECTION P2803

- - RELIEF VALVES

- - - P2803.1 Relief valves required.

Appliances and equipment used for heating water or storing hot water shall be protected by:
- - - - 1. A separate pressure-relief valve and a separate temperature-
relief valve; or
- - - - 2. A combination pressure- and temperature-relief valve.

Being as point-of-use tankless water heaters ... well ... "heat" water, and the fact that they are used for "heating water", they should have T&P valves just like water heaters which "store" heated water have.

Which brings up manufacturer's installation instructions and the code.

- P2801.2 Installation.

Water heaters shall be installed in accordance
with this chapter and Chapters 20 and 24.

Originally Posted by Richard Stanley

.
Also, B vent pipe not allowed - except in certain situations where it is used as a sleeve with the solid vent pipe inside of it.

B-vent is specified for some models/ manufacturers of tankless water heaters, Bosch and Paloma come to mind, for example see pp 9 here:

http://houseneeds.com/shop/manuals/b...00pinstall.pdf

Originally Posted by Michael Thomas

B-vent is specified for some models/ manufacturers of tankless water heaters, Bosch and Paloma come to mind, for example see pp 9 here:

http://houseneeds.com/shop/manuals/b...00pinstall.pdf

Michael,

That also specifically establishes the 'one foot rise' before going horizontal or elbows that is often asked about here.

Also on page 9:
- 3.6 Venting
- - Minimum vent pipe diameter: 5 inches
- - Minimum vertical vent height: 6 feet, with no elbows
- - "Establish 12 inch rise before any elbow"

and then again in Fig. 9
- "ESTABLISH A ONE FOOT RISE BEFORE ANY ELBOWS"

Also note that the IRC and IFGC both state 5 foot minimum rise and this one states 6 foot minimum rise.

Originally Posted by Matt Fellman

I just remember it by doing it after every 36th time I test all of the my GFI's.... Is there an easier way?

LOL! Humor appreciated Matt