Thread: Quick Connect on TPR valve discharge pipe

Came across a TPR discharge pipe connected to the valve with one of the push on quick connect devices. I dont like it, doesnt seem like the strength in the connection is sufficient should the tpr valve discharge. The pipe also rotates easily at the connection. I think a soldered connection is better in this application. Any one seen this before? What are your thoughts.

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I don't think it would be a problem.

How about the plastic fittings inside the quick connect. Is there a concern with these melting in high temperatures?

Originally Posted by Lanny Freng

How about the plastic fittings inside the quick connect. Is there a concern with these melting in high temperatures?

If your talking about press on fittings such as Shark Bite, they are approved for hot water.

Which brand was it?

Many popular push-fit connectors are tested and approved for use throughout the entire plumbing system.

Originally Posted by Dom D'Agostino

Which brand was it?

Many popular push-fit connectors are tested and approved for use throughout the entire plumbing system.

If it is a Shark-Bite fitting used on copper piping, then a bond wire needs to be run with the piping jumping each Shark-Bite fitting, or a bonding jumper could just be installed pipe-to-pipe around each Shark-Bite fitting as the Shark-Bite fittings *are not* listed or approved for bonding - that is from the manufacturer when I called them and asked them that question.

Originally Posted by Jerry Peck

If it is a Shark-Bite fitting used on copper piping, then a bond wire needs to be run with the piping jumping each Shark-Bite fitting, or a bonding jumper could just be installed pipe-to-pipe around each Shark-Bite fitting as the Shark-Bite fittings *are not* listed or approved for bonding - that is from the manufacturer when I called them and asked them that question.

Are you suggesting that the TPR drain pipe needs to be bonded?

Originally Posted by Rick Cantrell

Are you suggesting that the TPR drain pipe needs to be bonded?

No, just pointing out that, as Dom said, "approved for use throughout the entire plumbing system.", Dom expanded the discussion to include "the entire plumbing system" which means bonding if the piping system is metallic, such as copper.

If it is a Shark Bite fitting - rated to 200°F - and the TPR - rated to 212°F, then the difference in ratings may make for window of opportunity for a problem to occur with the fitting.

Depends on the fitting and what it is applied to. I note you referenced "quick connect" which I would equate to a threaded one side, and ball spring quick connect mated fitting - such as used in hosing example the threaded quick connect fittings plastic or cheap brass which are used on garden hoses and fittings, and for futher example quick connect air tool/compressor hose. Those would not ever be allowed as both interface as threaded fittings to the rod, pipe, tube, or hose connectors. Likely further not be approved under the plumbing code for both potable water systems (i.e. lead/brass content) NSF or ASTM, and furthermore the TPRV discharge plumbing must also meet potable plumbing system standards so as to not cross contaminate the potable water supply. Many "quick connect" fittings also have backflow or auto shut off valves within as well - these too are not allowed ANYWHERE in either the discharge system or the drainage system for TPRV discharge or thereafter converted (after exposure to atmosphere is converted to drainage) TPRV drainage systems.

More importantly, was this in the DISCHARGE system OR the DRAINAGE system (Big difference!) TPRV discharge is special waste (under pressure AND extreme temperature). Discharge is converted to DRAINAGE where exposed to atmosphere. There is no special considerations for DRAINAGE - it follows all the regular for DWV. If discharge reducing the ID is not permitted anywhere from the valve outlet until after the discharge is converted to drainage.

Ratings for plastic pipe and tubing temperatures are at specific PRESSURES. Using the absolute highest temperature, for example for sch. 80 CPVC is incorrect - as that highest temperature is at lower pressures - as the pressure is increased the highest temperature allowed is reduced.

As far as shark type fittings I know of none which are rated or approved for use in the special waste application of TPRV DISCHARGE which would not either compromise the wall of the material engaged in and which further would not reduce the ID of the discharge system anywhere after the TPRV outlet, such that if within the fitting expanded, further reduced to the tubing again at the outlet side and also reduce the max pressure capacity of the tubing or pipe where employed at high temperatures.

Remember bite fittings at 200 degrees F are further limited to that temperature at a reduced PSI/pressure of same. TPRVs discharge at higher pressure AND temperature - at those pressures (far in excess of 80 psi) the temperature ratings are much less. TPRV discharge (not drainage) is special in that it is both high temperature and pressure prior to release of energy to atmosphere (that open discharge point - above the floor, above an indirect drainage receptacle, etc.).

HTH.

Just had this thought. I'm not trying to start an argument.

I understand pressure ratings for pipes, however I'm not clear on one thing...
Is it the pressure that the pipe is holding? Meaning it is a closed system and the pipe must hold a specific pressure.
Or, is it the pressure of the water flowing thru the pipe? Since a TPR overflow pipe is open on the end, it really can't build up or even hold pressure.

My line of reasoning (possibly flawed, I admit) is that a pipe rated to "hold" a pressure of, say 150psi, might be just fine shooting water thru 4 feet at 175psi.

Like I said, its just a thought, and I don't know the answer.

I've seen many TPR's leak from too high a pressure, and the water temp is less than 120 degrees.

Originally Posted by Jack Feldmann

Just had this thought. I'm not trying to start an argument.

I understand pressure ratings for pipes, however I'm not clear on one thing...
Is it the pressure that the pipe is holding? Meaning it is a closed system and the pipe must hold a specific pressure.
Or, is it the pressure of the water flowing thru the pipe? Since a TPR overflow pipe is open on the end, it really can't build up or even hold pressure.

My line of reasoning (possibly flawed, I admit) is that a pipe rated to "hold" a pressure of, say 150psi, might be just fine shooting water thru 4 feet at 175psi.

Like I said, its just a thought, and I don't know the answer.

I've seen many TPR's leak from too high a pressure, and the water temp is less than 120 degrees.

It's a combination of both temperature and pressure.

The reason the T&P relief valve discharge line is allowed to be CPVC is that shortly after the water starts flowing, the water temperature starts dropping.

This is because the hot water escaping from the tank through the T&P relief valve is replaced with cold water from the cold water supply, and the longer the T&P releases water, the cooler (less hot) the water is, and in no time at all the temperature is well within the rating of the CPVC piping.

Remember the pressure cooker?

The water holding and heating compartment while firing or heating is under pressure. As water heats it expands. The temperature required to heat water to steam flash is different at varying pressure levels psig. As pressure equalizes (lowers) the temperature to steam flash return/approach nearer to the sea level (standard pressure) value at 212F or 100C. Higher pressures allow super heated water, for example increase of 15 psi above atmospheric can support boing point to 121C or 250F. Lower than standard pressure (higher ltitudes) atmospheric support lower boiling points (boiling point of water drops by approximately 1C per every 294 meters of altitude - or 1F for every 540 feet of altitude) causing the boiling point of water to be significantly below 100C or 212F.

Water and steam resist compression. Steam flashover expansion is dramatic.

With positive pressure main, the hot water valves closed, and heat trap(s) in place, Until the TPRV opens the system is effectively closed. Pressure equalization is limited to fluid dynamics and the expansion rate (heat still applied in a run-away situation). Energy (heat) released as pressure reduced as that discharge to free air thus conversion to drainage.

I happened to see pretty much what you described this afternoon, on the TPR extension pipe.

Also make sure those whips are properly secured in place. Those T&P relief valve discharge lines which are not metallic need to be strapped to the side of the water heater or to something, otherwise they will become whips swinging about.

Jerry, do you have a code reference for that??

Originally Posted by Jack Feldmann

Jerry, do you have a code reference for that??

Jack,

PEX: This is from the Aquapex Installation Guide:
- "Along vertical runs, install supports and a mid-story guide every 4 to 5 feet at each floor."
- - The run starts with a support and securing at the fitting it is connected to, in this case the T&P relief valve discharge opening. Thus the PEX needs to be supported and secured at the end, and if the vertical run is long, within 4 to 5 feet of each end (equivalent to going through a floor).
- "Bends within 6 inches of a connection require a tube talon or bend support (for ³⁄₈", and ¹⁄₂" AQUAPEX). For ³⁄₄" and 1" tubing, support is required for bends within 10 inches of a ProPEX connection."
- - Many should also have a "Metal Bend Support" or "Tube Talon" (from installation guide).

CPVC: The Flowguard Gold installation guide is not specific like the above.

Years ago I called both manufacturers and asked them about securing the T&P relief valve discharge line, both stated that the piece hanging down the side of the water heater needed to be secured so it would not whip around when the T&P relief valve pops off.

Code-wise, like many other things, nothing specific in the code, you need to go to the manufacturers.

Give them a call next week and see if they say the same thing about anchoring that discharge line, it has been 10 years or so since I called, you've got me curious to see if they have changed or if they say still the same thing.

Looking forward to what they tell you.