Pex is Pex in radiant slabs?
globaldiver
| Posted in Energy, Heating & Insulation on
I’m working on a design for a home shop (my personal shop). 30×50, and I’m really wanting to put in a radiant heating system in the slab (which I’m planning on 6 inch slab). Among the different Pex’s, are some more suitable for in-slab use than other? My local Home Depot sells a 500′ roll of 1/2 inch pex for about $199…….but I can’t judge if this is suitable or not. –Ken
Replies
Wirsbo is top of he line.
It must be het pex and not for aqua
Excellence is its own reward!
I agree with piffin
I always use Wirsbo.
you should pick your tubing depending on your heat source. If your boiler and all its components are non-ferrous you can use Wirsbo aquapex, if not or if you have not decided on a boiler yet use Wirsbo hepex this has an oxy-barrier.
Thanks Kevin
Thanks. I'll scout around for it. I hadn't given thought to the boiler, or whether this will be open or closed loop (probably closed, and I may want to try to tie solar into it as well. Aside from the expense, would one of the "tankless" water heaters be suitable to heat the water?
Ken,
I've never seen HD carry Pex tubing. I'd be curious to know who the manufacturer is. Find out if its Pex-A , Pex-B or Pex-C. If they can't tell you ...run away.
You don't want to use HD's PEX if it's the same stuff they sell out my way.
Wirsbo will be about 50% more than the HD PEX, and for 2000' of tubing that will be about another $450.
But with the Wirsbo you won't have to take a jackhammer to the slab in a few years.
Money well spent.
What is the differance , other than the O2 barrier? I got pex from Radiantec and from Menards both were rated 180* at 100 psi. Radiantec is "clear" and Menards is an orange/brownish color has a pottable water lable. The Menards stuff seems to be easier to make a tight bend. I don't know what HD sells ,but would think that it would be about the same as Menards . Don
The Home Depot stuff here is Qest (or Quest, I can't remember) by US Brass; they have a whole line of the hose, fittings, manifolds, etc. This is for potable water. I couldn't tell from the label whether it was A, B or C, and there was no one around to ask the evening I was looking at it.
Don,
There are different ways to cross-link HDPE to get PEX. One of the methods is superior to the other two. Even though PEX may have the same temp/press stamp, it still doesn't mean it's equal.
My thought is that I can always buy inexpensive on ssome things now and upgrade later...I can always upgrade to a better stove, a better toilet, a better table saw...but once you bury that PEX, it's there to stay.
Until you have to jackhammer it out to make repairs.
Have you read this thread about PEX failure?
http://forums.taunton.com/n/mb/message.asp?webtag=tp-breaktime&msg=27298.1
There may be info in there that you might find informative. Maybe not. Find out what kind of PEX HD and Menards are selling (A, B, or C), then make an informed decision.
You'll love RFH. Excellent choice.
What is the differance between ABand C pex? I always though that pex was the same ,and the only differance was in the fact that some had the al foil encased in it. Is here a way to tell by the markings on the tube ? mine has the potable water stamp from NSF.I have Radiantec tube in my basement now and it sure is nice .
Marking A, B or C on a pex tubing relate to the manufacturing process, not the quality. Although, there are some differencies between Pex types, such as pressure ratings.
Here is a good article about types of PEX tubing http://www.pexuniverse.com/content/types-of-pex-tubing
Peter, you're being a little too ubiquitous. Ease off a bit lest you be accused of commercial spamming.
I read the thread in your post after I replied. I also looked in my Radiantec lit. It does not have any info on the way that there tube is crosslinked . They have been in business for 23 years now. I still need to know if the lable has a clue of how the tube was crosslinked. You know that you can't get the answer from the stock boys at the store. Most of them are POed because they have to be there inorder to get the paycheck.
For what it isi worth , here are the lable markings that I have:
Tube from Menards:
CSI DURA PEX tubing 1/2" CST SDR-9 ASTM F-876 F877 100PSI@180*F
NSF pw (a trade mark) CSA B 137.5-97 POTABLE WATER H.U.D. (another tm) L-02 10/31/00 R-259
RADIANTEC tube:
RADIANTEC HEAT EXCHANGER TUBING 1/2" (CST- OD) 100 PSI@ 180F ASTM F876/F877 PEX SDR9 .070 5/01/97 A4X X3
I was wondering if the A4X and the CSA B had any thing to do with how the tube was cross linked. Is CSA B some Canadian standard? Who is CPI ?
Nice choice for shop heat. I did the same with a 20 x 30 shop three years ago. It's so good because there's no ductwork to carry dust into the house. And no baseboards to keep clean. And it's wonderfully comfortable.
I don't know what kind of tubing my contractor used.
While you're considering a custom shop, perhaps you'd want to install dust collection duct for the table saw in the floor. It's nice not having an obstacle overhead or crossing the floor. You can always not use it, but it's real tough to add it later.
I've been thinking about doing that with the ducting. At first I was thinking of forming up "channels" in the floor (which I could cover with plywood later) to run the ducting in, along with power. The more I thought about it, though, I concluded I'd just embed 4 inch PVC below the slab and use that. I'd probably run some electrical conduit the same way to bring power to the most probable location of the tablesaw......providing I have confidence enough in the layout of my shop before I'm physically in the space.... --Ken
I built the shop at the same time along with a new home, so I didn't have time to lay out the shop as I would have liked. So I know what it's like trying to guess the locations of machinery. Fortunately, I only had to decide on a location for the table saw and dust collector. All the other equipment was along walls so I could run the duct any time I wanted as I added equipment. I put the saw pretty much in the middle of the room so I had good clearance in all direction for handling sheet goods or long boards.
I ran duct from the table saw to the dust collector. I extended the duct in the opposite direction, stubbing up on the wall opposite the dust collector, so I could connect all the equipment on the far wall under the floor instead of running duct all the way around the room, which would have been longer and would have crossed windows and doors.
One thing I did not do well was that I used PVC conduit for the power outlet for the saw. What I should have done is use PVC, but on the last piece, the vertical one that comes up thru the slab and holds the box, should have been rigid steel conduit (threaded to the PVC under the slab with a threaded coupling). Some day I'm going to knock into the outlet box and break the plastic off.
I strongly agree with the Wirsbo...and I'd use hePex even if you think you may not need it. It only costs a little more and the oxygen barrier will allow you to not worry about oxygen getting in your system...whatever you do choose.
I'd also say you can't run too many conduits below slab around the building and outside.
I agree on the "you can't have too many....." I did the same thing when I ran new sprinkler lines around the yard. The trench has enough extra cables, empty PVC pipe with rope left in it to pull later things, etc., that I couldn't backfill all of the dirt from the trench. Like I told my wife, I'm not too lazy to do the work the first time, but I'm sure too lazy to do it a second..... --Ken
People are talking about 300 and 500' rolls of 1/2 PEX. So let me point out, DON'T run more than 200-250' in a run, shorter for higher BTU/sq ft applications. Split a 300 roll in to two 150s and divide a 500 into 3 166s. Heat delivery rate, responsiviness, and uniformity will all be much better. $50 more on a bigger manifold is cheap.
"empty PVC pipe with rope left in" is a very helpful hint. Running rope with each section you lay is a lot easier for a beginning than snaking or blowing one through later. Not that electrical conduit has sweeps versus tight 90's in PVC water pipe. And that, even with sweep, you are allowed no more than 5 90's in a run. Not that you could possibly pull through five 90's so keep it to 3 or less, IMO.
David Thomas Overlooking Cook Inlet in Kenai, Alaska
At the time I left the extra PVC in the trench, I didn't know about the blowing a line trick. With an extra full scuba tank, I could've really shot a line through! But, it was just as easy to use up some 1/4 inch yellow poly line.
Kenai, huh? I spent a summer in Soldotna back when I was in college, and had a job down past Kenai cleaning oil from old WWII liberty ships beached to make a dock......one of the messiest jobs I ever had.......
Good ideas on running it to opposite walls. Did you use 4" PVC? And, a very good tip on the electrical. I hadn't thought that one through. --Ken
No. I used galvanized duct. I think it was 5" or 6". The sizing was done for me by Onieda Air Systems, the maker of the dust collector.
Because galvanized is not water tight, it can only be used under a slab where there is no chance of water. That was true in my case because the slab was on crushed stone and above grade. It would not be advisable in, say, a basement. I put a bead of silicone caulk on the male end of each joint before insertion, and wrapped the joint with wide vinyl tape to seal it virutally air tight. To keep the duct from pulling apart during backfilling, I put two pop rivets in each joint, but only on the upper half (the 10 o'clock and 2 o'clock positions) so they would not snag wood shavings.
The dust collector inlet on the table saw has a ½" mesh screen over it so nothing large enough to clog the duct can get in.
Have fun, it sounds like it's going to be a nice shop.
Ken,
Check out tubing from Kitec - it's pex-aluminum-pex. What that means is that it has a thin layer of aluminum in between the two layers of pex - a nearly impervious oxygen barrier. An added plus with Kitec tubing is that when you bend it, it stays bent; makes installation easier. Additionally, Kitec is joined to their manifolds using compression fittings - no expensive expansion tools to buy. Their web site is http://www.kitec.com - it's the Mercedes of radiant tubing.
On a side note, don't forget to put down insulation under the slab ( 2" of blue board, my recommendation) as well as insulate around the perrimeter of the slab, down to 2 feet.
I'm already on top of the foundation insulation, and on at least 4 feet or so in from the footer. I've been following the discussion in another thread on whether you need to insulate the entire slab or not, and opinions are fairly strident each way. May boil down to whether or not you have any moisture under the slab, and in my country, that sucker is going to be bone dry......so I'm still making up my mind about insulation under the entire slab. Also undecided about blueboard vs. the white stuff with a foil face.......I think the blueboard is significantly more expensive.... Not that this is going to be a cheap job, but I don't want to spend where I don't have to... --Ken
Stone and sand are good conductors of heat. I'd definitely insulate under the entire slab! If you really need to save money then go with thinner insulation in the center. But, I suspect (but don't have the data to prove) that you'll save back the cost of standard insulation in reduced energy usage. Energy costs will only go up over the years.
EPS is the foam
EPS is what you want under the slab. AKA beadboard.
It's cheaper and treated with borate to keep the bugs from munching it.
The Type II stuff is more than adequate for a 6" slab.
R-control is all over the country, you should be able to find some locally.
Cheap is good and in this case also the best for the purpose.
Joe H