Pex connection on a Water Heater

I saw this installation today on a brand new water heater. This is a new construction home. It is a high efficient gas water heater. According to the IRC you must have 18 inch clearance from the top of the water heater to your Pex connection. But I am thinking since this is a high efficiency with an induced fan, that it not necessary. What does everyone else think?

Where is that code?

May have to do with piping manufacturer installation guidelines.

Being that’s a power vent check with the manufacturer instructions.

Here is the code:

**[size=3]604.11.2 Water Heater Connections. **[/size][FONT=Gill Sans MT,Gill Sans MT][size=3]PEX shall not be installed within the first 18 inches
(457 mm) of piping connected to a water heater.

I also contacted bradford white, the service tech I spoke to, didn’t think it would be a problem. Due to the closed combustion.

The “code” is clear, and makes no mention of the type of heater.

That’s the UPC Code, not IRC.

Further to your question Ed was there a dielectic fitting there because although the pic is quite blurry it looks as though the fittings are galv. coming from the Hw tank

Why would you need a dielectric fitting between plastic and galvanized? My question is regarding what looks like a valve at the hot water T. What was that for?

[FONT=Tahoma][size=4][FONT=Tahoma][size=4][size=3]The valve that is coming off the hot water side is require, per the manufacture. There are pressure limits on Pex that the manufacture specify. [/size][/size]

PEX Operating Pressure &
Temperature Limits


[/FONT][/FONT][FONT=Tahoma]160 psi@73ºF (1.10MPa@23ºF)[/FONT]

[/FONT][/FONT][FONT=Tahoma]100 psi@180ºF (0.69MPa@82ºF)[/FONT]


[/FONT][/FONT][FONT=Tahoma]Chlorinated Water[/FONT]


[/FONT][/FONT][FONT=Tahoma]80psi@140ºF (0.55MPa@60ºF)[/FONT]

[/FONT][/FONT][FONT=Tahoma]Recirculating Loops[/FONT]

[FONT=Wingdings][FONT=Wingdings][/FONT][/FONT][FONT=Tahoma]80psi@140ºF (0.55MPa@60ºF)[/FONT]

[FONT=Tahoma]There was no dielectic fitting present. There should be no need for one.

That is not the IRC. The UPC is not adopted in this part of the country.

So what type of valve is it since temperature sets the pressure? Would it not need to be installed within the water heater to get a proper temperature reading?

Since it has lesser temp and pressure requirements, shouldn’t it be installed where the TPR valve is located? In all the new construction that is using PEX, I have never seen a 2nd valve like this, but then I also have not looked at the specs for the TPR valves.

What is the allowed temperature on the TPR? This is why it cannot be PEX because PEX is rated for lower temperatures and sometimes pressure. Howerver the AHJ may have allowed it knowing the chances of pressure are limited due to two PRVs installed.

Just got off the phone with the Uponor (Wirsbo brand PEX) technical support / code supervisor and explained the application below.

  1. A 2nd valve is NOT required.
  2. The normal TPR valve is adequate for all residential potable water plumbing systems.
  3. PEX has an extreme high limit use of 210 degrees at 160 psi for 24 hours in case the TPR valve fails.
  4. The 18" rule is in effect for all types of water heaters.

Hope this helps.

Per the IRC, PEX is acceptable for the TPR discharge piping.

In Quebec, the 18" rule does not apply if its an electric water heater even though it does in the U.S.

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This is not a code issue, it is manufacturer’s requirement.

In my book it says 180 F.
It also says do not connect directly to a water heater.
Some PEX can only handle 120 psi, so who is wrong?

I checked directly with the largest manufacturer of PEX in the world. The specs I posted were directly from the person in charge of tech support / codes.

I would take their word over a general pipe supplier anytime. The chart you posted was for non-pressure applications but it did show PEX at 210 degrees.

Since I just finished a re-pipe with PEX, I can tell you that there is sure a difference between brands. The interior diameter of Zurn brand (sold at HD) is much smaller than Uponor/Wirsbo and the fittings are sure not interchangeable.

So on the pipe it says 210 F with no pressure. This tells me it cannot be installed directly to the water heater. It reduces to 180 F after pressure is applied. So as a drain pipe it is fine but not as a pressurized hot water line connected to a Hot Water Heater. IMO