PEX Tubing for Plumbing

Ron George

I have recently investigated several Plumbing installations where salesmen have done a good job of selling PEX but not the engineering.
In each case the job was to go in with soft Copper and closed cell plastic insulation UG. The PEX Reps sold the job as PEX and when asked if the system needed to be insulated they said no. They never insulate PEX because it's plastic!
In both cases, two large homes do not have hot water to the remote areas of the house. Imagine how the new homeowner in an 11,000 sf home feels when he has a 2 million dollar hame and cannot get a hot shower.
The moral of the story PEX Piping for plumbing systems underground must be insulated.
We have also found that when the PEX tubing penetrates the floor slabs several Tubing Mfgrs reccomend rigid sleeves.

Rick_91

This is a helpful guide

Regards...

Ron George

Undergroung PEX piping for Plumbing

I find it interesting that the design guide does not mention insulation for underground pipes. It also mentions that the piping can be bundled together. I think they need clarifications in the design guide and in installer training that all domestic hot water underground piping must be insulated to prevent heat loss to the ground. They should also mention what may seem obvious but not clearly stated in the design guide and training classes for the installer, that hot and cold water tubing should not be bundeled together because of heat transfer and possible loss of heat in the hot water piping.

Rich Kontny_3

A simple recirc system would be needed whether it was covered or not. Otherwise the system could have used point of use water heaters.

Pex is not the culpit, poor design sounds like the problem.

Rick_91

For underground

Here's a couple of choices...

Mark Custis

Ron George

If you are trying to take a shower call me.

PexA, Copper or galvinized steel pipe, will point out bad design and poor planning.

Larry Weingarten

Underground hot water piping...

... has the problem of ground water/moisture doing a wonderful job stealing the heat. In California, we're considering a code change to insulating all hot lines and putting them in conduit when in ground. It's a good way to keep the lines dry and maybe replaceable some day in the far future.

Yours, Larry

Mark Custis

Sorry Larry I missed

It was in the next county.

Hey CA. is behind we use insulated transportation piping in OH.

Ron George

Underground Water Distribution with HW recirculation

The problem in the case I recently investigated is the home is extremely large and the underslab water line is over 270 feet from the water heaters to the master bath.
The pipes were laid in a trench in close proximity to each other (bundled).
No Recirculation:
When the recirc pump is turned off it takes a very very long time to get hot water (over 12 minutes)and when there is HW the temperature is inadequatefor a long time until the surrounding ground is heated up.
Recirculation:
When the recirculatiuon line is turned on it heats up the ground and the adjacent cold water pipe. Then it takes a very very long time (over 12 minutes) to get cold water.
Lesson Learned:
The lesson in this situation is underground water distribution lines should be insulated per the plumbing code which references the energy code.
All PEX manufacturer's should be calling for insulation on underground hot water distribution piping in their design guides. The Manufacturer's should also call for a minimum seperation of HW and CW lines in the trenches to prevent heat migrating from HW to CW. www.rongeorgedesign.com

Charlie from wmass

Who would have thought a piping material used for radiant heating would transfer heat so well? ( please note sarcasm)

John_162

Hey only a CPD should know that

gerry gill

you have a very nice web site Ron.

I really like it..your right about the insulation for sure..

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