Water Heater Discharge Tube Question

[Roback]

Am doing a remodel. I have a water heater in a closet on a ground floor that has a exterior wall. I have a pan with a pvc discharge that exits the wall. Do I need to install a copper discharge tube from the TPR valve outside the wall, or can I just run it down into the pan? I am in California. Also the heater is elevated, so not sure I can even run it below the 6" code requirement.

 

[FullySprinklered]

God only knows what the rules are in California. Locally, they're not particular about the material used, as long as it goes outside and ends up 6" above the ground. Don't run it into the pan. Especially, don't run it into the a/c condensate pump. You can use an elbow to get down to the six inch level if necessary. I would suggest also that you not run through the inspection department waving your arms to tell on yourself if you think you've got it wrong.

 

[Sponsor]

 

[mangoManFT]

I'm in CA and recently had a new hot water heater professionally installed. At first the plumber had the discharge pipe empty into the pan, and the pan drained thru PVC to the outside. This did not pass inspection. The proper solution was to run another line to the outside made of copper, which is what the plumber did. If I remember correctly, our local code is equivalent to the state code, but of course your situation may be different. In any case, as the other poster stated, don't run the discharge tube into the pan.

 

[hj]

If you run it in to the pan, expect to have it overflow within the first few seconds when the valve discharges. The discharge CANNOT be PVC, and has to be "full size" to its termination. In this area, "full size" means at least 3/4" i.d. so PEX, CPVC, corrugated copper flex lines, etc. ARE NOT approved.

 

[Reach4]

If you run it in to the pan, expect to have it overflow within the first few seconds when the valve discharges. The discharge CANNOT be PVC, and has to be "full size" to its termination. In this area, "full size" means at least 3/4" i.d. so PEX, CPVC, corrugated copper flex lines, etc. ARE NOT approved.

Sounds like one of the few good uses for galvanized pipe for permanent use today that I can think of.

Do you really think that 3/4 inch CPVC would be disproved by an inspector? Suppose the heater input line was 3/4 inch corrugated copper? One inch CPVC or PEX would be clearly big enough.

 

[Jadnashua]

Keep in mind that the T&P valve opens for one or both reasons: excessively hot or excessive pressure. THe plastic based pipes just cannot safely handle extreme pressure OR temperature possible when one of those opens fully. NOw, a slow drip from over pressure, maybe, but it could cause a plastic pipe to warp over time which isn't good.

There are often very good reasons for the code being what it is that may not be obvious without considering all possibilities...codes are written for the (sometimes obscure) what-if situations.

 

[JerryR]

My home built in Florida in 2001 had

Keep in mind that the T&P valve opens for one or both reasons: excessively hot or excessive pressure. THe plastic based pipes just cannot safely handle extreme pressure OR temperature possible when one of those opens fully. NOw, a slow drip from over pressure, maybe, but it could cause a plastic pipe to warp over time which isn't good.

There are often very good reasons for the code being what it is that may not be obvious without considering all possibilities...codes are written for the (sometimes obscure) what-if situations.

Hum? My 2001 built West coast Florida built home had 3/4" CPVC for all 3 lines, hot, cold and T&P. The 3/4" CPVC T&P line dumped outside though a CBS wall.

I believe max service temp for CPVC is 200dF.

 

[DonL]

A pvc pipe is better than no pipe.

Just point it in a direction that you want HOT water flooding.

CA has special rules. You can not even buy Guns or Bullets is some areas. Everything causes cancer there. What is up with that ?


I like to party there, but would not want to live there.

 

[hj]

3/4" PEX, CPVC, and corrugated flexible connectors are ALL smaller than 3/4" i.d. which is the standard for "full sized" piping.

 

[Gary Swart]

Just use galvanized pipe and be done with it. Copper would work great, but it's too pricey for this use. Plastic? Forget about it.

 

[Jadnashua]

Most T&P valves open at 210-degrees F as a result of high temp and at 150psi for pressure. In reality, because of the length of the sensor, when it reaches 210 part way down, it could be significantly higher at the top of the tank (Watts says about 244-degrees where it is typically being discharged from - water doesn't boil at 212 when under pressure). Plastic pipe is not generally designed for this temperature or pressure (pressure spec generally goes down as the temperature goes up but it might be okay at a cooler temp). Plastic pipe needs to have thicker walls than copper, and the exterior diameter is required to stay at a constant OD (meaning that the interior diameter will be smaller than a stronger pipe). Temperature and pressure restrictions, plus the ID is restricted verses something like copper says it could be a problem, and likely not installed per the specs or code.

 

[JerryR]

If you run it in to the pan, expect to have it overflow within the first few seconds when the valve discharges. The discharge CANNOT be PVC, and has to be "full size" to its termination. In this area, "full size" means at least 3/4" i.d. so PEX, CPVC, corrugated copper flex lines, etc. ARE NOT approved.

Looks like Sioux Chief makes an adaptor so the you can use a 1" CPVC pipe for discharge from a T&P valve. That way it meets the at least 3/4" "full bore" i.d. requirement.

http://www.siouxchief.com/products/...water-heater-connectors/tandp-relief-adapters

 

[hj]

As soon as you start discussing 1" ANYTHING, you have moved out of the discussion about whether a specific 3/4" line is adequate. As soon as the heater's temperature rises above 212 degrees, you enter a new world of "superheated steam" where the normal rules of flow do not apply. In other words, the fact that the inlet lines are ANY MATERIAL or size, has absolutely nothing to do with how the water is flowing from the T&P valve line.

 

[DonL]

A lot of the new water heaters have a Pressure sensor that shuts them Off due to Lo pressure (No water to heat) and Thermal shut down and over pressure. So "superheated steam" can not happen, That can be real problems.

They use CPVC in my Hood. Most let the water dump into the Garage sub level. We have 2 level slabs.

Some say the T&P should be tested. I say do not mess with it, or you will have a leak.


Replace is better than test, because it will most likely need replaced after your test.

 

[hj]

quote; A lot of the new water heaters have a Pressure sensor that shuts them Off due to Lo pressure (No water to heat)

Maybe SOMEDAY I will see one but have NEVER so far. Unless the water was drained, there is always water to heat.

 

[FullySprinklered]

I replaced a water heater a couple of weeks ago. The pop-off line was a 3/8od copper tube that had been inserted into a stub of 3/4 copper coming out of the male adapter, connected to the T&P valve. The 3/4 pipe had been crimped down to hold the 3/8 tube and soldered in. The pipe ran up and over to the outside wall and down into the washer drain. I've got pictures.
On a job yesterday, I noticed that the water heater in the garage had a 1/2inch pipe going down from the T/P to the vicinity of the W/H pan. The pan had a drain line which elbowed down and ended at the slab 16in below.
If you're going to f*** it up, might as well go all the way, huh?

 

[Terry]

Fullysprinkled,
Where are the pictures?

Also JerryR
CPVC MetalHead™ Water Heater Connectors

• Perfect for adapting to the T&P Relief valve and running a CPVC line to the floor drain 1" CPVC to 3/4 MA

Nice link.

 

[Bluebinky]

I replaced a water heater a couple of weeks ago. The pop-off line was a 3/8od copper tube that had been inserted into a stub of 3/4 copper coming out of the male adapter, connected to the T&P valve. The 3/4 pipe had been crimped down to hold the 3/8 tube and soldered in. The pipe ran up and over to the outside wall and down into the washer drain. I've got pictures.
On a job yesterday, I noticed that the water heater in the garage had a 1/2inch pipe going down from the T/P to the vicinity of the W/H pan. The pan had a drain line which elbowed down and ended at the slab 16in below.
If you're going to f*** it up, might as well go all the way, huh?

The TP drain in my house in Texas had 3/4 copper running under the slab and underground for about 35 feet into the septic tank. I'm pretty sure the house was never inspected.

 

[Reach4]

The TP drain in my house in Texas had 3/4 copper running under the slab and underground for about 35 feet into the septic tank.

I think that volume over a long time would not be so good for the septic system, and it would be easy to miss that the valve was discharging.

 

[DonL]

I think that volume over a long time would not be so good for the septic system, and it would be easy to miss that the valve was discharging.

LOL

Where do you read/learn that stuff ?

Seems like you would know if you have no hot water.