Hydronic heating in slab, PEX splice experience?

[extropic]

Does anyone have experience, good or bad, with the longevity of burying PEX splices in a concrete slab? I'm soliciting opinions based on actual experience over time. Will they last 50 years?

I'd like to expand the plumbing system in my shop building by installing a stall shower (in the shop bathroom) and a mop sink on the opposite side of wall a from the shower.

I'll need to tear up the slab about 2ft x 9ft to connect with the drain servicing the nearest toilet. The trench will run perpendicular (of course) to my PEX in the slab so I'll probably expose 7 to 9 PEX runs. I'll do my best to avoid damaging the PEX but that seems high risk and I need to be prepared to install splices before I take on the job.

I'll use what ever fitting the PEX manufacturer recommends. I understand that, after pressure testing, I need to install heat shrink tubing over the splice to prevent metal contact with the concrete. Any other comments?

TIA

 

[theoldwizard1]

Does anyone have experience, good or bad, with the longevity of burying PEX splices in a concrete slab? I'm soliciting opinions based on actual experience over time. Will they last 50 years?

PEX has not been around for 50 years.

 

[extropic]

PEX has not been around for 50 years.

What's your point?

By the way, your statement seems to be false.

"Myth: PEX Tubing is not reliable.
Fact: PEX has been extensively used in Europe and USA, giving it a 50 year track record of strong performance and reliability. Rapid growth of PEX installations in the US over the past 2 decades serves as an indicator that the product is becoming widely accepted by home owners and contractors alike."

http://www.pexuniverse.com/pex-myth-and-facts

 

[mygarageone]

PVC drainage piping got the same bad **** when it came out , I read and heard all the negative comments about it in the 60's . Yet it has out performed everything they said it would do.
Now about Pex connectors under ground . Use S.S rings , brass connectors and protect the joint from the concrete and your good go.
How do I know , past experience . I did wrap my connections with a foam insulation to protect it .

 

[slackdaddy1]

Myth: "PEX has been extensively used in Europe and USA, giving it a 50 year track record of strong performance and reliability"

Fact: PEX has NOT been used extensively in the USA for the last 50 years. It has only taking hold as one of the more mainstream option by builders in the last 5-10 years.

Not being rude, but I do not blindly believe every statement put out by salesman,

Nick

 

[mygarageone]

Myth: "PEX has been extensively used in Europe and USA, giving it a 50 year track record of strong performance and reliability"

Fact: PEX has NOT been used extensively in the USA for the last 50 years. It has only taking hold as one of the more mainstream option by builders in the last 5-10 years.

Not being rude, but I do not blindly believe every statement put out by salesman,

Nick

Wrong , Pex was being used in Europe in the 70's so it has a 50 yr track record . I have some experience with this stuff , I'm old enough to remember reading article's about it back then.

 

[alexb2000]

I have a house with pex heating buried in the slab. One of the pipes was accidentally cut during construction forcing a splice. That splice has been in place for 10 years no issues, so far.

If you are really worried about it you can use Stainless fittings as an extra measure of protection.

 

[mygarageone]

More info , Pex was developed in the 1950's and improvements were made via Dow Corning and Thomas Engel in the 1960's . It like any product has some failures but unlike copper used underground or in concrete a very small % failure rate . Nothing is permenant but some things are far better than what we have had in the past .

 

[59 wagon man]

i'd say the real reason for pex was to lower labor costs. takes very little skill to run. the copper in my house is 53 yrs old and no problems. new coil of copper has a 50 yr warranty stamped on box.

 

[yeldogt]

Myth: "PEX has been extensively used in Europe and USA, giving it a 50 year track record of strong performance and reliability"

Fact: PEX has NOT been used extensively in the USA for the last 50 years. It has only taking hold as one of the more mainstream option by builders in the last 5-10 years.

Not being rude, but I do not blindly believe every statement put out by salesman,

Nick

I did my first PEX installation back in 1986 .. 30 years ago.still going. It was not new in 86.

To the OP -- they have been using the connectors since the beginning. I would not worry about doing it ... like buried CU splices .. the mechanical have proven to be reliable.

 

[mygarageone]

i'd say the real reason for pex was to lower labor costs. takes very little skill to run. the copper in my house is 53 yrs old and no problems. new coil of copper has a 50 yr warranty stamped on box.

Costs are always the driving force Behind product innovation .

 

[mygarageone]

You don't know how many copper in floor radiant systems failed because of the corrosion effects on copper. Some only a few yrs along and some 10 yrs but not many past 10 yrs.
But as we went on. We learned about oxygen diffusion and what it does to metal products , hence the stainless steel heat exchanger among other reasons.

 

[slackdaddy1]

Hey guys, my point was "Pex has not been used extensively in the USA for 50 years"
And it has NOT been.
I repair plumbing (and other things) in bank held properties, I am in 200-300 houses a year for the last 24 years. I have seen maybe 3-5 houses plumbed with PEX.
So no, it has NOT been used extensively in the USA for the last 50 years.

That said, I love the stuff. and to answer the original question, I would have no problem splicing in the slab.

 

[extropic]

Thanks folks. Sounds like a "OK" so far.

Blowing up a gale here this morning. Power's out. Running on batteries.

 

[yeldogt]

Hey guys, my point was "Pex has not been used extensively in the USA for 50 years"
And it has NOT been.
I repair plumbing (and other things) in bank held properties, I am in 200-300 houses a year for the last 24 years. I have seen maybe 3-5 houses plumbed with PEX.
So no, it has NOT been used extensively in the USA for the last 50 years.

That said, I love the stuff. and to answer the original question, I would have no problem splicing in the slab.

I was only talking about PEX for radiant .... plastic and potable water was a concern as far as I go. I first saw it in Germany ... my current new house will be the first build where I use it.

 

[alexb2000]

Thanks folks. Sounds like a "OK" so far.

Blowing up a gale here this morning. Power's out. Running on batteries.

Remember when you are looking for performance history that the heating PEX is O2 barrier and different than the Home Depot plumbing version. I have been using Veiga barrier PEX with good results:

http://www.viega.us/7138.html

 

[pstnbly]

There are PEX splice kits made specifically for slab applications. They have heavy heat shrink wrappers to isolate the fittings from the concrete.

 

[rburke65]

No experience here but as said the brass and plastic should be ok, and the shrink wrap sleeves should also be a positive. Hell, they use the shrink wrap on underground electrical splices.

 

[klrdiant]

the only issue is concrete reacting to the fitting

if you use wirsbo/uponor pex and their expansion ring system with their plastic fittings you won't have problems .. just join it and forget it

if i had to work with watts or heatlink or something that doesnt have proprietary inert connections, i use a brass fittings and crimp rings and i will literally cocoon the the hell out of the joint in electric tape .. you certainly could use shrink wrap i guess, just sounds like a pain in the ****, there's always a roll of electric tape in my truck somewhere .. you gotta keep the metal insulated from the concrete to avoid corrosion

also, make sure any splices are done in straight sections .. don't splice on a bend, it's a stress on the connection .. and remember that a fitting is a restriction and counts towards overall run length .. i count it as ten feet for ease of keeping stuff straight in my head .. its not super critical to have every run exactly the same length, but you also don't want huge discrepancies

 

[Jackfre]

Polybutylene is the pipe that raised hell in the industry. PEX has done well. I agree with the Uponor expansion method of install. As to your concerns about the joint, you could install and access box with a metal lid to be able to get to the joint. If you decided to pour the joint in, take careful X/Y measurements and put them where you can find them in the future. I have the 1/2, 3/4 & 1" manual expander die set from Uponor if you decide to go that way.It is like new. I see the set at SupplyHouse.com for $400. I'll part with the set in like new condition for $125.

 

[Radiantec Guy]

Regardless of how long PEX was used in the US, the answer to your question is: a spliced piece of tubing and fitting should last as long as the tubing if done correctly. My recommendations would be to install the coupling and pressure test to 100 psi for 24 hours. If that holds, wrap the fitting with plastic and secure it with electrical tape or similar. Concrete can cause metal to corrode if it comes in contact for extended periods of time. I would do this no matter what composition fitting you put in. Good luck!

 

[gnpenning]

I did my first radiant heat in the mid 80's with pex. During the pour they flipped a cigarette and let the air out. It was boxed out and later repaired then spot poured. No issue's over 30 years.

And yes they paid for it.

Not sure how your going to cut and break it out and keep a clean edge..

 

[walrus]

Polybutylene is the pipe that raised hell in the industry. .

Wasn't it the fittings that raised hell not the pipe itself? I have polybutylene on my solar DHW systems thats has been installed for 25 years, brass fittings not plastic.

 

[extropic]

I did my first radiant heat in the mid 80's with pex. During the pour they flipped a cigarette and let the air out. It was boxed out and later repaired then spot poured. No issue's over 30 years.

And yes they paid for it.

Not sure how your going to cut and break it out and keep a clean edge..

First, to most all replies; Thank you. I'm loaded with confidence that if I do a quality job, I don't have to worry about any splices leaking.

Now, I don't understand the significance of the sentence in red. Keep which edge clean? Please elucidate.

I didn't build or commission the building so I can only go by what the PO told me. He said the slab was 6" thick, 2" rigid foam insulation underneath. I wouldn't be surprised if the slab was less than 6" in the office/bathroom area (about 800sqft). My preliminary plan would be to:
1) Charge the tubing with 20PSI air to make a cut-thru obvious.
2) At incrementally increasing depth, saw a slit down the center of the concrete area to be removed.
3) If I can saw down 2" without cutting into any PEX, I would make enough saw cuts to facilitate removing the concrete down to the 2" depth.
4) The next step would be to fire up the heater and try to map the location of the PEX using a UV Temp Sensor.
5) The mapping should allow me to remove substantial rectangles of concrete between the PEX runs.
6) Next would be breaking up the concrete remaining (maybe 4" square) that is surrounding the PEX runs. The perfect outcome would be all concrete removed and no significant damage to any PEX.
7) I'm thinking that my exposure of the PEX (concrete removal) will need to be at least 2ft wide to allow cutting each PEX in the middle and tying back the stub to allow about 12" wide access to remove the insulation and trench as required.

Which brings me to another concern. What about mesh/rebar? Whichever I find, it should be deeper in the slab than the PEX (PEX tied on top of it) right? I'm going to have to learn a satisfactory technique for replacing the reinforcement aren't I? Where to look for the "how to"? What keywords to Google?

Thanks again.

 

[gnpenning]

Your steps 1-7 kind of cover it in theory.

Any metal in the slab will make breaking the concrete up were you don't damage the Pex more of a challenge.

I understand your plan to cut the slab in smaller chunks and enough area so you have room to work. I'm not sure how much of a connection the Pex will have with the concrete.

It does sound like your planning to take it slow and easy and do what you have to do.

Let us know how it turns out and what you find works the best.

 

[rburke65]

I would be concerned with replacing the wire or rebar.