During a mechanical inspection in North Carolina, the inspector indicated that the drain piping from the drip pan under our hot water heater could not be PVC. The drain pipe runs approximately 6' to the outside of the house and discharges 12" above grade. We used 1" PVC for the drain piping as the drip pan that we purchased (and all of the others available we learned after a return trip to the hardware store) came with a PVC fitting. I then checked the temperature rating for schedule 40 PVC which turns out to be 140°F and compared it to the Max temperature of my hot water heater, which according to the label is 160°F.

So, in order to exceed the temperature rating of the 6' of PVC drain pipe, the water heater would have to be operating at its max temp (which would easily exceed the 120° max temp at the faucet) and leak significantly enough to fill the drain pipe without heat loss while not leaking enough to overflow the drip pan and render the drain pipe irrelevant.

Furthermore, our local hardware store no longer carries CPVC as PEX is now the go-to and we were unable to find a PEX fitting that would fit the pre-drilled hole in the drip pan.

In all - we have tried to find another solution besides PVC and haven't had any luck. Is the inspector's claim accurate in this case and if so what is the solution?

Side note - the same inspector also told us that the PRV drain pipe that came with the water heater did not meet code because "it didn't look like CPVC".

Thanks for your help!

then run it in CPVC to make him happy. the fitting at the pan is just a male adapter with a couple of thin flat washers secured with electrical nuts.

The pan's drain is ALWAYS PVC, and if he cannot tell CPVC by looking at it he is not much of an inspector.

After a little more digging, it turns out that the only state that allows PVC pipe for water distribution service is Florida. According to the 2012 IPC, the drain piping from the drain pan can be of material listed in table 605.4 - Approved piping for water distribution service (Not PVC).

While this makes absolutely no sense to me, it seems as if it is in the code book. Apparently the manufacturers of drain pans that provide PVC fittings didn't get the memo?

Side note - Drain pan piping requires a rating for 180°F at 100 psi. At a pan depth of 1.5", even if it was completely full for weeks, it would never even reach 1 psi.

It depends on what your definition of "Water distribution service" is. I am sure the municpal water companies are using PVC for mains and also the laterals to the building.

It's been years since we could use PVC for a water heater drip pan drain. CPVC is what I use.

Is there a code section that states the pan drain SHALL use the piping shown in 605.4? Is the inspector a home inspector or the city/county building inspector?

My feeling is the pan drain pipe should fall under this definition -

DRAINAGE SYSTEM. Piping within a public or private premise that conveys sewage, rainwater or other liquid wastes to a point of disposal. A drainage system does not include the mains of a public sewer system or a private or public sewage treatment or disposal plant.



Edited 1 times.

A heater pan does NOT convey potable water.

a 'RUNAWAY' heater juuuust MAY discharge 180 or hotter water into the pan if it were to leak


case in point:

old heater leaks from a top connection

said leak corrodes thermostat in closed position

tank is now a 'runaway' leaking 209 degree water until the T-PRV opens at 210

theoretically

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

To the runaway heater situation:
The life expectancy of a properly installed gas hot water heater is 10-15 yrs. So for a "runaway heater" event that may occur once over that time span I'm required to have a drain pipe that can hold 180°F water at 100 psi, just in case the thermostat gets stuck? Come on. The chances of a toilet overflowing are far far greater and there's no "just in case" drain pan under the toilet with a drain line rated for an individual that eats Mexican 5 days a week... yet.

The clear error in this code is the fact that the pipe has to be rated for holding temperature AND pressure when there is no possible chance that it could be pressurized. PVC would be more than adequate at 0 PSI and >200° F.



Here is the wording of the code:

504.7 Required pan. Where water heaters or hot water storage tanks are installed
in: (a) remote locations such as a suspended ceiling, (b) attics, (c) above occupied
spaces, or (d) unventilated crawl spaces, the tank or water heater shall be installed
in a galvanized steel pan having a material thickness of not less than 0.0236 inch
(0.6010 mm) (No. 24 gage), or other pans approved for such use.

Exceptions:
1. Electric water heaters may rest in a high-impact plastic pan of at least 1/16 inch
(1.6 mm) thickness.
2. Water heater mounted on concrete floor for floor drains.

504.7.1 Pan size and drain.
The pan drain shall not be less than 1.5 inches (38
mm) deep and shall not be obstructed by the appliance. The pan shall be drained by
an indirect waste pipe having a minimum diameter of 1 inch (25.4 mm). Piping for
safety pan drains shall be of those materials listed in Table 605.4.

We are required to use CPVC as well.

Quote

Piping for
safety pan drains shall be of those materials listed in Table 605.4.

What material is permitted by said table ?

Case closed.

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

That means after about 30 seconds the drain pan will be overflowing and it makes no difference WHAT the pipe is made of, the house will still be flooded with super hot water. Which is why WE are required to discharge the T&P valve outside the building and NOT into the drain pan.



Edited 1 times.

correct

one runs the T-PRV discharge pipe to a safe location, either a floor drain or outside

but

the pan may be 'catching' 200+ water for a while BEFORE the relief trips

D'OH

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

I just hate to tell a plumber they have to take the supplied 30 cent pvc fitting out of a drain pan and replace it with a 5 dollar cpvc fitting. Seems like over kill