Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.
If our community has helped you, please consider making a contribution to support this website. Thanks!

need pre sleeved or components to sleeve and insulate 3/4 inch pex-A

Options
archibald tuttle
archibald tuttle Member Posts: 1,153
in THE MAIN WALL

i've got to bury half a dozen 10 foot lengths of pex for both domestic and hydronic service under slab that is in conditioned space and this is literally the first time i'e had to do that where an inspector has to sign off (At least on the domestic runs). it looks to me like the domestic insulation requirement is R-3 for the hot water. there are inexpensive assemblies presleeved in corrugatd HDPE that look pretty rugged but have no insulation (although they describe themselves is "insulated") e.g. https://www.homedepot.com/p/PLUMBFLEX-Pre-Sleeved-PEX-3-4-in-x-300-ft-Red-HDPE-Corrugated-PEX-A-Tubing-with-Insulated-Sleeve-Commercial-and-Residential-Use-HPSP-S56522/330007165

now I honestly think that for short runs this would be OK from a performance perspective even for heating pipe (except that one isn't barrier tubing) because neither the pex nor the HPDE sleeve are highly conductive material and there would actually be air between the two for most of their diameter and the lengths and thus loss we're talking is quite limited. But I don't think the hard headed inspectors are up for applying that kind of thinking compared to code.

there are preinsulated versions of 3/4 inch available that I assume are OK for burial and to come through the slab, e.g. uponor: https://www.supplyhouse.com/Wirsbo-Uponor-F6040750-3-4-Pre-Insulated-AquaPEX-Tubing-100-ft-coil

but they don't have the same highly protective corrugated sheath. There are some pretty expensive versions that do combine insulation and protective sheath that are overkill and a half for this project but nice product, e.g. rehau insulpex * https://www.rehau.com/us-en/mechanicalplumbing/technologies/radiantallfh/pre-insulated-pex-piping

but it does not appear to be available smaller than 1".

then I could do it myself with armaflex tuffcoat. https://www.armacell.com/sites/default/files/2025/10/21/ArmaFlex%20Tuffcoat%20-%20Product%20Brochure%20-%20en-GB.pdf

it seems to say that it is available in 6M rolls although I can't find anyone selling it. I don't think it is split but I'm not sure. at the lengths i'm dealing with I can buy straight pipe and pull it through fairly easily and while it is meant to evoke a certain toughness it looks nothing like as tough as corrugated sleeves.

you can buy the corrugated sleeves independently so i could use some armaflex and then slide it into a sleeve. e.g.

https://www.homedepot.com/p/TekTube-1-5-in-x-100-ft-Flexible-Corrugated-Red-HDPE-NON-Split-Tubing-Wire-Loom-Non-Metallic-Conduit-RHDPENS112100/333298321

it just strikes me odd that there isn't an LCD product that splits the difference on some of these properties for short runs under conditioned space and is readily available vs. the wood boiler or industrially oriented burial stuff. any direction anyone can point me?

thanks, brian

*in the cases of the presleeved pex-A i'm assuming that the pipe in them is approved for domestic water although that could be a false assumption. ironically, some barrier pex is not approved for domestic applications although it is the same quality of tubing that the same manufacturers offer with domestic approval but apparently they have to go through a separate certification process and since it is principally aimed at hydronic service they don't bother to get the domestic approvals.

Comments

  • archibald tuttle
    archibald tuttle Member Posts: 1,153

    got off the phone with armaflex and they recommend this product. it is code compliant thickness/r-value for hot water and from what I can understand has a somewhat robust exterior shield that can be direct buried, nothing like the HDPE sleeves but better than straight armacell product. and the "tuffcoat" product is apparently more oriented toward above ground UV protection.

    still about the same money or less to put regular armaflex into corrugated hdpe albeit I'd have to do a few 20 ft. lengths to see if it is easily possible and worth the trouble to get into the sleeve. the corrougated sleeves i'm seeing readily available top out at 2" (maybe ID although there are no reliable specs) and 3/4 pex plus 1/2" insulation is going to be 1 7/8 inches. was thinking maybe a finger trap pull on pex inserted into armaflex would get that done on the end of and electric fish?

  • hot_rod
    hot_rod Member Posts: 26,368
    edited October 28

    you will need some sort of rounded end on the pex to pull it through. And talcum powder.

    I remember the EcoPex coils came with a rounded end cover for pulling

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • archibald tuttle
    archibald tuttle Member Posts: 1,153

    @hot_rod practical as usual. so I have two pulls/pushs to worry about. getting pex into armaflex and then getting the armaflex/pex assembly into a ridgid conduit. i'm going to try 20' straight lengths of pexA

    when dealing with shorter lengths putting the armaflex on the pipe has been kind of a push pull game. I can't remember that I have ever done 20 feet before. my inclination is to push a flexible rod electric puller through the armaflex, use a reverse cone reamer on the end of the pex so I don't have abrupt outer edge. i'm going to try a 3/8 bolt 5/8 hole lag shield tightened into the end of the pipe with some electric tape wrapped around it if needed since the pipe is a little ove 5/8 on the inside. and then i'll wind a wire around the extruding lag bolt head to pull by.

    and then to pull that assembly into the corrugated cover i can use a chinese finger trap puller over the insulation and pipe. i'm hoping with straight pipe i'll be able to use 2 inch "loom". that seems to be what they call corrugated conduit. the only problem I have is most manufacturers do not specific the ID and OD of loom and some 2" is actually under 2" inside. the pipe in the required 1/2" wall armaflex is about 1 7/8" so I don't have a lot to spare. and there isn't really such a thing as 2 1/2" loom. could get 2 1/2" flexible pvc but seems a little overkill. 🤞

    obviously i'm not going to have easy replacement in the 2" but i'm not thinking that pex protected like this is going to need replacement in my lifetime (even if I were still young ;- )

    brian

  • psb75
    psb75 Member Posts: 1,089

    Just a reminder to use O2-barrier pex pipe for all hydronic heating purposes. And consider the pex fittings type that may need to move (when/if pulling) in corrugated "loom" material.

  • archibald tuttle
    archibald tuttle Member Posts: 1,153

    @psb75 with you on barrier*. couple runs are domestic which requires standard pexA. my supplier of straight 20 foot lengths does have barrier tubing also, i don't know if its A or B or if I have a choice, but I don't believe it matters. they want A on the domestic side. i'm not sure why but what they say goes. it's easier than arguing about it.

    *actually I am wondering if I should run copper for the baseboard temp heating feeds anyway. i wouldn't necessary design for 180 degree temps but they give rise to 10 times the oxygen infiltration that 104 degree does. although the ridiculous campaigns against mining in this country must be contributing to the fact that 7/8 OD soft copper coils are out of stock in many places and through the roof where they aren't. twith the conversion of so much plumbing work to pex, and the prevalance of aluminum in heavy electric service, you'd think copper wouldn't be astronomically expensive, but you'd be wrong.

    that said, for the distance involved, copper is like $9 a foot with insulation and these assemblies i'm working on are going to stand me maybe $2.50 plus labor so it's not an earth shattering expense. it just bugs me that copper is so unnecessarily expensive. the other thing besides the price penalty I don't like is that the pex itself is less heat conductive and in both insulation and corrugated hdpe it seems like a much better burial system from a heat loss point of view.

  • GGross
    GGross Member Posts: 1,708

    Can you use solid agriflow as a sleeve? Seems easier to work with you could build the whole sleeved and insulated assemblies and then lay them in a trench. Badger pipe also sells some non-barrier pre-sleeved and insulated rolls, I think they can cut to length and typically include a control wire in the sleeve, and I did see they offer something in 3/4" but I think its 2 pipes

  • archibald tuttle
    archibald tuttle Member Posts: 1,153

    @GGross has seen the agriflow solution in various previous installs i've come across. but none where it was big enough for pipe plus insulation. i get the feeling that size would be harder to corner than corrugated pvc.

    I did find duraline brand loom that is literally the only corrugated duct that lists its inside and outside diameter and the 2" nom is actually a few hundredths over 2" on the inside and I can obtain it for rational cost so i think i'm going to try it.

    of course all this searching has got me wondering why they call it "loom"

Categories