dealing with twists in the pex on staple up

skyking1 · April 20

We started pulling the pex in today. We have about 2/3rd of a loop in and the tubing is getting some twists in it. What is a good strategy for dealing with that? We have staple up plates to go over it and thought we would stop pulling it in and start chasing it with the plates.

The pex is legendflex 1/2" from legend valve. It's a 3 layer pipe with the oxygen barrier covered with another layer. It does bend a tight radius and we are not having even a hint of kinking with it.

Mad Dog_2 · April 20

You have to hold the pex in one arm & flip it as you go. You'll feel it fighting you as it goes down...that is the time to flip it. Mad Dog

psb75 · April 20

Its easiest if you keep the roll of pex on an "unsspooling" reel. Rent or buy one, or make your own. The pex should NOT have any "stored twist" in it as you put it in place.

Jamie Hall · April 20

https://forum.heatinghelp.com/discussion/comment/1852942#Comment_1852942

This. Never lift it off the coil — always unspool. This also goes, by the way, for electrcial wiring… rope… cable…

Mad Dog_2 · April 20

You can keep your spools & uncoilers...Ive used them all. Prefer my own arm...Done small and larger radiant & snowmelt jobs this way. Mad Dog

skyking1 · April 20

Thanks guys. I tried threading it through from one end, and not pulling loops through from the equipment room and enough for the home run as I have seen on countless videos now.

😩

My brothers and I got our **** kicked!

Now I get to pull it back out, re-coil it, actually figure out the turn back point and start over.

@Mad Dog_2 that is how we laid the floor in, and the ground loops. We rolled it out and flipped it when it asked for it. Thank you.

The staple down plates I got from Vevor are a joke. Nowhere as thick as advertised. As seems to be the case for me, I didn't know again what I didn't know.

We have switched gears and are now getting pricing on extruded aluminum plates like the uponor joist trak and the Legend duo, and the thermofin out of Montana.

I may just coil up this legenflex and save it for the next slab job, and switch to 3/8" as @hot_rod suggests in many cases. I think th legendflex is fine, but we are not spring chickens and any easy button I can push at this point in the build, I may push.

ethicalpaul · April 20

Thanks guys. I tried threading it through from one end, and not pulling loops through from the equipment room and enough for the home run as I have seen on countless videos now.

Depending on your layout you will need a twist occasionally. With no twist at all you will be fighting. Like mad dog said you can feel it

The uponor extruded staple up (although “screw up” is a more accurate name but not desirable for marketing reasons) performed amazingly good in my deep personal experience of one install.

skyking1 · April 20

Thanks @ethicalpaul I have read some of your other helpful posts. I just got here. I am sorry I have two posts going in hydronics I suppose I will pick one and run with that. If my calcs of ~15BTU per SQ foot are good, my gut says switch to 3/8" tubing and keep the 250' total run lengths including the return. in extruded omega plates of course! I found a post with an IR study here from a while back and it is amazing how much better the heat is extracted from the tubing.

I made a fundamental error. I viewed the PEX as readily sending heat out into the bay and the staple up plates as a way to secure it. PEX does not readily "send the heat out". The tight fitting Omega style plates EXTRACT it out.

The good news is we figured it out on the first day, and that day included doing a bunch of other things like some joist blocking and squash blocks and routing plumbing through before totally contaminating the field with runs of PEX.

ethicalpaul · April 20

Thanks for your kind words

I made a fundamental error. I viewed the PEX as readily sending heat out into the bay and the staple up plates as a way to secure it. PEX does not readily "send the heat out". The tight fitting Omega style plates EXTRACT it out.

This is a pretty common misunderstanding I think, nice job figuring it out quickly! I think I have read about people just chucking it into the joist bays.

skyking1 · April 20

I was not "chucking it in" I was going with a single source of information I fixated on. Radiantec uses staple up plus the foil plus the insulation method. I read all their info and was fat dumb and happy with it. Now I feel I have a better handle on it thanks to this site. I think the money up front for good heat extraction will pay dividends on lower SWT and higher efficiencies.

The heat pump is an inverter unit and I think it will run an ODR curve very well indeed.

ODR curve was just one bit of new information I picked up here.

I found this in the manual and if I can tweak the graph points it will do what I need.

I can work with the X-axis values as they are. My heating temp is 23F so -10 C is not terribad.

PC7060 · April 20

https://forum.heatinghelp.com/discussion/comment/1852976#Comment_1852976

By his use of “chucking it in”, I think Paul was referring to installs which completely ignored any manufacturer instructions. Not your specific install.
learning when to stop and try another approach reflects good judgement which in my case is only developed by bad experience. 😎

skyking1 · April 20

https://forum.heatinghelp.com/discussion/comment/1852980#Comment_1852980

yes I was just fleshing out how I got there and really how happy I am to be Here.

hot_rod · April 20

Rent or borrow an uncoiler, it makes it much easier to work the pex.

In a bind to do my own shop, I threw together this uncoiler. I made this with my shop stool and a bucket.

Getting and keeping the pex warm helps a lot, even out in the sunshine for an hour makes it easier to "loop"

Kaos · April 21

Sometimes when you get yourself in a bind, or twist in this case, a coupler doesn't hurt. Not a fan of buried fittings but sometimes it is inevitable like when you reach the end of the spool and still have some length to run. Unlike a slab, at least with staple up, you can always get to the fitting if things go south.

Recently was pulling some pex, used a piece of 2x4 between two shelves to hold the coil up. Works in a pinch.

Important part with staple up is to air seal the rim joist area. This means spray foam or rigid foam sealed in place with canned foam. Air leaks there, besides increasing heat load, reduces the amount of heat you can get out of your floor heat, bad air leaks might mean the floor heat won't be noticeably warm.

skyking1 · April 21

It is new construction with ICF basement. The top of the pour was OK, but I dialed it in with a laser afterward so the sealing foam under the sill was tight and even.

The east end is hung on ledgers so I have walk out entries back, front, and carport. No steps.

The floor I can heat there is 15" from the outside wall line.

Then I stepped the stemwall down to acommodate traditional plate and rim boards, on the daylight end. I'll work at sealing that up more. The blower door test will tell the tale.

psb75 · April 21

Radiantec…the Scourge of the hydronic radiant heating world.

hot_rod · April 21

https://forum.heatinghelp.com/discussion/comment/1853036#Comment_1853036

A coupling or two is not a big deal. If you can use and expansion type coupling, I doubt you could even notice any pressure drop. Watts/ Heatway used to sell spliced Entran at a deep discount. The couplings were sealed under a shrink sleeve.

JMWHVAC · April 21

An uncoiler is NOT needed. We got rid of ours long ago. Pull off several coils, flip the roll, now the coils will be coming off the opposite side of roll and will "cancel out" the coils from the other side. It is the same principal as reverse wound boxes of wire. Most times I only flip the roll approx every 50 feet of tube but each person needs to find their way.

skyking1 · April 22

I stopped by the office and they have two of these that I can use.

https://www.uponor.com/getoptimizedimage/34437c39-ac0c-452e-9f83-a11a176a40f7/e6062000?siteName=USA&height=576

I spoke to Brad at Radiant in Bozeman. Nice guy. he said they had some 3/8" ThinFin C that had been stored in the wet and had some surface corrosion that I could get at a discount. if it is not in the "C" I don't care how it looks as long as it does the needful.

It will look great after the insulation goes over it and the sheetrock :)

About insulation: I have a kitchen island I don't want to heat, but I like the idea of just keeping the PEX grabbed over the whole length. My thought is to go ahead and put the track in and run it, but omit the insulation right under that island. That way the heat will be halved at least going into the subfloor. It is a conditioned basement below and that heat will not go to waste.

Mad Dog_2 · April 22

The first snowmelt we did, the Rep put 3!!!! Uncoilers on the material list. They were NOT happy when we cut the fat outta their Golden Egg list...ha ha. Mad Dog

hot_rod · April 22

https://forum.heatinghelp.com/discussion/comment/1853227#Comment_1853227

Maybe leave the plates out from under the island or any cabinets really. The tube can still go across the area, but without the conduction, the heat output will be minimum.

ethicalpaul · April 22

https://forum.heatinghelp.com/discussion/comment/1853227#Comment_1853227

I don't think this will halve the heat. The heat is traveling primarily via conduction, not radiation or convection. That part that is convection is going to tend to stay up in the joists anyway. But as others have said, it depends on your conditions in your basement. Since you say it's a conditioned space below you might find almost all the heat is going to go into the floor that would in the insulated areas.

@hot_rod 's suggestion (that I failed to see at first) is great though, leave the plates out in that area and you'll be gold

skyking1 · April 22

I thought of that. I figured it would be better to secure it as you had explained that it basically traps the tube so it can't walk, and just jacks some more internal stress into it rather than actually growing in length.

I see that a 4' section is not going to grow much so I was over-thinking that process. I had experiences with overheating a storage area before. My ski boots were under an old school waterbed that kept the space very warm. This accelerated the plastic degradation. Many years later I went skiing and did not notice the microcracking of the plastic.

On the first turn the boots just exploded. The entire sole section snapped off the upper and I went sailing down the slope like superman, skis sitting there in the snow. What do you do? pick up all your plastic litter and then ride the chair back down to rent some boots and skis.

dealing with twists in the pex on staple up

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