Pex connection on a Water Heater

[Ed Mitchell]

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?

[Joe Funderburk, CMI]

Originally Posted by emitchell

According to the IRC you must have 18 inch clearance from the top of the water heater to your Pex connection.

Where is that code?

[Marcel Gratton]

May have to do with piping manufacturer installation guidelines.

http://www.ppfahome.org/pdf/PEX%20In...20Handbook.pdf

[Christopher Currins]

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

[Ed Mitchell]

Here is the code:

604.11.2 Water Heater Connections. 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.

[Jeffrey R. Pope]

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

[Christopher Currins]

Originally Posted by emitchell

Here is the code:

604.11.2 Water Heater Connections. 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.

That's the UPC Code, not IRC.

[Scott May]

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

[Stephen W. Stanczyk]

Originally Posted by smay

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?

[Ed Mitchell]

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.

PEX Operating Pressure &
Temperature Limits

Water

160 psi@73ºF (1.10MPa@23ºF)

100 psi@180ºF (0.69MPa@82ºF)

Chlorinated Water

80psi@140ºF (0.55MPa@60ºF)

Recirculating Loops

80psi@140ºF (0.55MPa@60ºF)

There was no dielectic fitting present. There should be no need for one.

[Joe Funderburk, CMI]

Originally Posted by emitchell

Here is the code:

604.11.2 Water Heater Connections. PEX shall not be installed within the first 18 inches (457 mm) of piping connected to a water heater.

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

[Stephen W. Stanczyk]

Originally Posted by emitchell

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.

PEX Operating Pressure &
Temperature Limits

Water

160 psi@73ºF (1.10MPa@23ºF)
100 psi@180ºF (0.69MPa@82ºF)

Chlorinated Water
80psi@140ºF (0.55MPa@60ºF)

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.

[KEVIN WOOD]

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.

[Stephen W. Stanczyk]

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.

[Joe Funderburk, CMI]

Originally Posted by kwood

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.

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