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Underfloor PEX Plate advise

TAGTAG Posts: 94Member
Have decided to add underfloor radiant to part of my current project not being gutted. last time I did a large area was a long time ago and used Radiant-Track. Extruded 4" x 4' panels with a center slot that the PEX snaps into -- 8 pre-drilled holes for mounting to subfloor with screws. They came from a company on LI in NY -- Radiant Technologies. Using google -- The product name gets me a different design where the tube snap to the side.

What are people using for this application? Reg PEX ...or PALP?

I used the Radiant-Track at the time because it was a full 4" wide and very heavy -- had the holes. Uponor makes the same design -- not as wide and thinner. Don't see the holes. Over the years I have used the thin style design that covers the PEX -- but only for warming situations in walls and showers -- one kitchen. I'm using Warmboard in the rest of the house -- think best go with the heavy plates.

I see a company in MT making 4" wide/ thick ..... even 8' long. ThermoFin by Radiant Heat and Design.

The space I am doing is an L shaped loft area (living room) ..... The main part of the room is 28' x32' -- side is 10x15 .. so a bit over 1000sf
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Comments

  • GordyGordy Posts: 9,247Member
    Extruded plates with omega style channel.
  • IronmanIronman Posts: 4,897Member
    We like this, holds 2 pipes instead of one:


    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • SENWiEcoSENWiEco Posts: 44Member
    @tag Check out this study It helped me make up my mind on which plates to use.
    theEnclosure.ca
    Sean Wiens
  • TAGTAG Posts: 94Member
    edited February 17
    :) .... thanks .. three different answers !

    Ironman -- I saw that one ... it looks interesting and I like how it holds the pipe and it also looks easier to install. You find it's got the performance -- it's the same cost as the thick extruded.

    Gordy -- That type seems to be popular and it does address a fault with the typical design of that style that don't really grab the tube. less expensive vs the other two examples

    SENWIE -- I saw that and that's the company I referenced that makes the 8' length.

    The room has very high ceilings -- 3/4 plywood w/ 3/4 wood flooring. It the highest level in the building ..
  • IronmanIronman Posts: 4,897Member
    edited February 17
    It's capable of about 20 btus per sq. foot output at 120*SWT - depending upon your floor coverings. 1.5" wood thickness is gonna be around an R1.5 value.

    Have you done a heat loss calc?
    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • In the past, we used the ThermoFin with excellent results. We now use Ultra-Fin with equal success. One run per bay makes for a faster install with less tubing.

    Just make sure you calc. your heatloss and follow the instructions. You have to keep 2" above and below the fins clear since this product heats by convection, not conduction.


    Often wrong, never in doubt.
  • GordyGordy Posts: 9,247Member
    edited February 17
    > @SENWiEco said:
    > @tag Check out this study It helped me make up my mind on which plates to use.


    That’s a good study, but no one uses copper tube. That being said I’m sure the heat spread is identical for pex,but temps would be different.
  • GordyGordy Posts: 9,247Member
    As you can see by the study tube fit in the channel is everything.
  • TAGTAG Posts: 94Member
    edited February 17
    Ironman: The space is 996 sf w/ Heat load of 16371BTU. I'm rebuilding a church (my residence) This is the front upper triangle of the building --- the lower floors are all rebuilt and have Warmboard down .. the lowest is a slab w/ PEX. Ideally -- want to pipe the same temp as the Warmboard ... my guess is taht may be too hot for the slab.

    The house has ducted HVAC -- so there will be additional heat.

    The front wall is going to be the exposed stone of the building so the load includes a bit for that .. the room is open to those below.

    The upper line is the floor level -- the house has 5 levels. We decided not to replace that level and keep the existing floor.
    CROP.pdf 626.9K
  • TAGTAG Posts: 94Member
    edited February 17
    Allen -- That's interesting. Do you just use regular PEX? Warmboard at one time only recommended AL PEX -- that's what they sell .. but they now say you can use others. evidently the AL gives the best performance.

    One thing I did leave out -- the level bellow has a lots of small aperture recessed lighting. Never hire a lighting architect! So -- I'm a little tight .. and I have to insulate.

    This project is one of those -- we went this far why not ... do ! Some floors were uneven and it had a bad set of steps -- it's from the 1870's. So we ripped out the lower levels to fix stuff -- as it is going back I'm saying. Have to do the Warmboard -- as we heated the slab in the addition. The HVAC is way over my original budget

    Here is a shot from the new kitchen addition -- It's that whole upper level that's old and needs the plates. With the ducted HVAC -- we were not planing on doing anything. Then the the thought was -- why not just do it in the center area where furniture goes.
  • IronmanIronman Posts: 4,897Member
    That's about 16.5 btus per sq. ft. You should be fine as long as you don't add anymore floor covering.

    Since you're not totally relying on the floor to heat the area, I'd try running it off of the same SWT as the rest of the system and see how it does.

    How about posting some pics of your boiler, piping and controls so we can see the present setup. It may not be that complicated to create another water temp zone if it needs it.
    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • IronmanIronman Posts: 4,897Member
    If you p/m me, I'll give you a cost estimate.
    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • Ulta-Fin has a list of PEX tubing you can use; pretty much all the established manufactures.

    Our first Warmboard job we used regular PEX and there were some serious expansion/contraction ticking sounds. Luckily, the owners found it comforting. I believe PEX-AL-PEX has less of an expansion coefficient and will be quieter.
    Often wrong, never in doubt.
  • TAGTAG Posts: 94Member
    edited February 18
    Alan - have only used the WB three times -- all with AL. Interesting that you had noise.

    I'm sort of fearful using an odd system.
  • hot_rodhot_rod Posts: 11,135Member
    The PAP is a little harder to work with if you have to thread thru holes in joists, and it can kink. Ir shapes better, has less movement from thermal expansion. This is true for transfer plates and UltraFin installations.

    I suppose the aluminum layer would make it a tad better heat transfer?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • Dave H_2Dave H_2 Posts: 321Member
    @TAG
    The Radiant-Trak from Radiant Technology is the exact same plate offered by Uponor.
    Radiant Technology (RTI) closed down quite a while ago and was an Uponor company. At the time, we were merged into Wirsbo, which later on, changed names to Uponor.

    Uponor calls the plate Joist-Trak. Same dimensions, same length, same holes.

    My personal preference of install from underfloor with plates would be to use 3/8" pex. It is by far so much more flexible to work with and when plates are used, no difference in heat output. The only difference would be the overall length of each loop, with 3/8" pex, you need to be shorter than compared to 1/2". In your case, it would be the difference of one more loop on a manifold. 5 loops around 250' with 3/8" versus 4 loops around 320' with 1/2".

    Dave H.
    Dave H
  • TAGTAG Posts: 94Member
    Dave. The plates I have are about 3 7/8 wide. Some sites are saying the Uponor plates are 3.5 inches, other sites list them at 4". So I had some confusion -- like the predrilled holes.

    3/8 really ?.... That would be easier. Is there a drop in the output -- or is this just a function of more manifolds and another pump.

    Have used 3/8 PEX one time to keep the height down. (large wetbed kitchen). Used 3/8 with the plates in that same house to warm the walls in outside wall bathroom. Only because they sent me a box of 3/8 plates by accident and I had extra PEX.


    Ironman: This is all new -- figuring out the controls will come later. Boiler/indirect/radiant. Either a furnace or coil off boiler -- leaving towards furnace.

    For the radiant Warmboard does a design -- two manifolds - 5 and 7 loop. There is a slab at the lowest -- around 500sf. bathroom/dressing room. I can't remember how many loops -- I believe we did 8" OC. The 7 loop Warmboard and whatever I do with the underfloor plates is going to have to be done w/remote manifolds. Mechanical is tight -- and at least 25' away
  • Dave H_2Dave H_2 Posts: 321Member
    TAG, no drop in BTU output, just a little shorter in overall length.

    The width of the plates are probably listed as 4" wide in a catalog sheet (round up) but a spec sheet will have it listed to the actual dimension. Again, the output will be virtually the same.

    Dave H.
    Dave H
  • hot_rodhot_rod Posts: 11,135Member
    I agree with Dave in that the 3/8 is more user friendly 225- 250 max length would be my suggestion.

    Watch out for some of the 3/8 insert pex fittings, seems the opening is about 1/4" ID, the spun copper type specifically. So if you have a bunch of manifold fittings, or end up with couplings the pressure drop starts adding up.

    Mr Pex has an interesting dual tube plate,. fits two tube sizes. So if you had a long loop requirement for a distant loop you could throw a loop of 1/2" in.

    I wonder how it would perform with two tubes per plate? :)
    Or one tube for heating, the larger tube for summer mode cooling, keeping the two systems seperated.

    I believe ThermoFin was the first extruded plate on the market. looking closely you will see the extra aluminum around the groove to plate connection, compared to other knock offs.
    This is where ThermoFin gets it's unique tight fit, obviously adding some cost as it all about the weight of the raw material with Russian controlled aluminum price these days:)

    Less expensive extruded or stamped plates the tube often falls out after you drive it in.

    Aluminum in quantities is priced the day it arrives at you dock, nobody wants to bid or hold a price.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • kenjohnsonkenjohnson Posts: 23Member
    I just completed my installation - designed and installed it myself (with some connection assistance from my geothermal installer/plumber) - details here https://forum.heatinghelp.com/discussion/163346/would-like-some-feedback-on-my-radiant-design-plans#latest

    I used the Wirsbo plates and 1/2" Wirsbo PEX-AL-PEX. The Wirsbo plates have the channel opening facing down, not sideways (can't imagine pushing the PEX in sideways). I chose 1/2" PEX for lower pressure drop in the loops. It was harder to bend and move, but glad I did it as I'll save on pump electricity costs for the duration of the install. I did use a self-tapping screw 3/4" long with a hex head and these went in really quick with a cordless drill without pre-drilling of any holes. My install crew was me and two other guys - that is the minimum, I think. System works exactly as designed, even though the 1x6 subfloor meant a little poor contact (sometimes) between the plates and the bottom of the floor.

    I can't imagine how hard it would be to put plates over PEX - snapping PEX into plates was pretty easy.

  • When we got up to speed installing ThermoFin, we used a collated screw gun.
    https://i.ebayimg.com/images/g/Ys8AAOSwmtJXYDK8/s-l300.jpg
    Back then it was corded and now, with cordless tools it's gotta be a lot faster.
    Often wrong, never in doubt.
  • TAGTAG Posts: 94Member
    Do you need a larger pump when using all 3/8 on a 6 loop manifold? ... The 3/8 kitchen install I mentioned above was for a very small kitchen area -- one loop and the space was open to two other rooms. I just stuck it first on the manifold -- I guess it's giving me less output vs the 1/2 in the other spots -- the flow meter was showing full flow?
  • SENWiEcoSENWiEco Posts: 44Member
    smaller tube increase resistance and work on the pump requiring larger pump with all other things equal
    theEnclosure.ca
    Sean Wiens
  • GordyGordy Posts: 9,247Member
    As far as pump size with 3/8”, that’s why you shorten the loops. To keep the head manageable.
  • hot_rodhot_rod Posts: 11,135Member
    Here are the pressure drop charts for the two sizes of tube. You could shorten loop length or drop flow a bit to get the 3/8 to match the 1/2 head.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • TAGTAG Posts: 94Member
    Hotrod -- That's past my pay grade. I understand the terms .... but don't understand the fine details.

    When I did my first couple of jobs back in the early 90's -- I had someone very knowledgable help me -- also had Dan's book.
    Common piping was 1" copper to the manifolds from the main 1 1/4 copper boiler loop -- that would get me plenty of flow (GPM) using 1/2 pex from the manifold to the loops. I think the biggest manifold was 7-8 .... I used Emabssy and they had flow meters to fine tune.

    I really don't understand what occurs -- when one would substitute 3/8 Pex in a large loop .. I can see from the graph the head increases ... with the 3/8 and if I need 120 degree water at 1gpm and 250' loop ... that may be a problem.

    I don't know what flow I need.

  • GordyGordy Posts: 9,247Member
    Then you would do 120* water in a 200' loop. You would just need more loops.
  • TAGTAG Posts: 94Member
    Gordy -- so a 1" line feeding to the manifold and 7-8 3/8 loops will work with a typical Grundfos 15-42 or current equilivent?

    Obviously know the 1/2 will work -- as I have done it.
  • GordyGordy Posts: 9,247Member
    edited February 19
    Now comes the math :)

    The psi drop for 3/8 pex @120 degrees, and .5 gpm is 2.5psi per 100'

    2.5psi x 2.31 converts to 11.55' of head for a 200' loop with .5gpm.

    IF each loop needs .5 gpm, and you have 7 loops you need 3.5 gpm to that 7 loop manifold.

    Now you go to the 15-42 pump curve chart.
    Find 11.55 feet of head, and go down to the gpm.

    As you can see on speed three gives you 7 gpm, and speed 2 is about 6 gpm.

    So plenty of pump. You can either go a bit longer with the loops, live with it, and dial in the flow with the manifold or better yet pick a more suitable smaller Econ circulator with a better matching curve.
  • TAGTAG Posts: 94Member
    Gordy -- I thank you. I'm going to study up a bit :)

    When I did my first Warmboard back in the early 00's when it had not been out very long. I was bit worried about the 12' spacing as I had always done 6' in my slabs and I never did a house where the underfloor plates did all the heat load .. so it's "are you sure this will work"

    It's not like I have seen or done 100's of jobs -- so I don't know how common 3/8 is for plates.

  • GordyGordy Posts: 9,247Member
    Your very welcome, and Nothings past your pay grade unless ;) you want the pay grade to pass you
  • TAGTAG Posts: 94Member
    Using my plans (see picture) and plotting out the bays and loops -- may have a problem with the 3/8 tubing length. The front wall of the building is about 28' wide. Trying to do three bays requires (6x28) 168' .... I'm still 25' away from the manifold location and 1 floor up (10') -- so that's another 70' of tubing. Best case is 238' - easy to go over the 250' if i have to go around something. The manifolds have to go under the steps at the crawl space.

    The living room space is about 29' deep -- I have 19 bays to fill.

    My thought was to do two loops that only try to cover two bays with each zone. (28x4) 112" ... I'm now a bay further away -- make it 75' .. I'm under 200' with each of them. That would give me 5 additional loops each doing three bays -- I'm closer to the manifold now and would be under the 250'.

    The front wall of the building is open stone -- so will the shorter loops flow faster and provide a bit more heat in that area? That would be beneficial. The other end of the room is open to the dinning room w/ Warmboard -- so it's going to get heat from the dinning and other areas.

    Have a side area also -- that's less important. Maybe 2 loops using 3/8 -- so a total of 9 loops of the 3/8.


    I'm trying to understand how much easier the 3/8 tubing would be vs the 1/2 inch ..


  • GordyGordy Posts: 9,247Member
    edited February 22
    Do two bays. 182’. Then as you get closer three. How big are the pex rolls you are going to purchase?
  • hot_rodhot_rod Posts: 11,135Member
    If you work with pex all the time 1/2" is not a problem. For a DIY or anyone not used to pulling pex, yes the 3/8 is much easier.

    I like regular A pex, Uponor or Mr Pex is about the most flexible. I've not tried PERT? Maybe it is even more flexible?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • TAGTAG Posts: 94Member
    Typically get the 1000ft rolls -- my plan was to get the plates into place and get the holes drilled .... get it all ready.

    There is a good chance I will run the PEX for the underfloor .. it depends on where we are on the project. The lower level is already poured with the PEX installed -- done by my plumber. My guess he will do the PEX into the Warmboard -- it's easy and needs to be done just before the wood floor is installed. He is doing the boiler and indirect -- manifolds. I have an HVAC guy for all the duct and mini

    Does anybody know who makes the PEX for Warmboard -- it looks like Mr. PEX. ... they use PAP. I'm in charge of getting that.
  • hot_rodhot_rod Posts: 11,135Member
    Any brand of PAP should work in the Warmboard. I'd stick with a brand name, not some low priced, no-name online product.

    I think a lot of the PAP is re-labeled Reifing brand, used to be anyways.

    Viega Fostapex will not work, it has a larger ID.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • TAGTAG Posts: 94Member
    The last I used Warmboard they had not started to supply the tube or manifolds. They have always advised (more than just recommend) AL Pex be used for both expansion and heat transfer. Mr PEX was first on the list ..... that's what I used .. still have about 500' in a box from that project. Warmboard now sells the tubing and manifolds and other related supplies. The tubing says Warmboard -- it's Al Pex. I know another consideration was the overall size -- it's got to sit properly in the Warmboard channel.

    The approved tubing list is much longer now, and not all of it is AL PEX.
  • RetrosPexRetrosPex Posts: 54Member
    TAG: I like 1/2 Wirsbo Type A. HePex. It is not at all hard to work with. Keep it warm, and it will be much more flexible. AL Pex is a bear to work with, but the nice thing is that when you bend it, it stays bent.

    I'm looking at the Thermofin for my project, but also noticed that RHT has new 6" wide extruded plates at a very good price. I'm going to order a few boxes to try them out on a bathroom before making a decision on ordering a bunch.

    I've never done or even seen a 3/8" installation. Personally, I would not do it because the one time possible advantage of it being easier to bend will be offset by higher pumping costs FOREVER. Electricity is not cheap, and is going up a lot all the time. It will never go down. Also, with a shorter loop length of 3/8' you need more loops. More fittings, longer manifold, etc.

    Just my 2 cents worth.

  • Dave H_2Dave H_2 Posts: 321Member
    @RetrosPex
    I unfortunately have to respectfully disagree about higher pumping costs with using 3/8" pex.
    When a heat loss is done for a room, the flowrate is determined by the heat loss. you then divide that by the number of loops used, so the total gpm is the same no matter what size pex is used.
    Example, 250 sq ft room that has a heat loss of 5,000 btu's per hour. Using a 10 degree F temp drop, gpm=btu/delta T*500
    gpm=5000/10*500= 1 gpm
    The amount of pipe needed is 250 sq * 1.5 (8" on-center spacing) = 375 feet of pipe needed. divide that by 300 for 1/2 pex = 1.25; so two loops are needed. 375/2=188 feet plus plenty for leaders to/from manifold.
    Divide the same number 375 by 250 for max length for 3/8 pex = 1.5; so two loops are still needed.

    These max loop length numbers are by no means in stone. Sometimes you can be longer, sometimes you need to be shorter.

    If you were to do an entire home in radiant underfloor, your joist spacing dictates how much pipe is being used no matter what. You should also install the pipe on a per room basis, you should never carry over into another room, it gets really hard to control the amount of heat that is needed in each room.
    So based upon that and my experience in only doing 3/8" pex installs, the number of extra loops on a manifold for an entire house may have increased by one or two loops.

    But for pump sizing here are the numbers;
    Its 1 gallon per minute needed no matter pipe size.
    The head loss is 1.78 foot of head for 1/2" pex, 5.22 foot of head for 3/8" pex and this is based upon 200' loops.
    Well within 007 parameters and so the electrical costs will be the same no matter what.

    Dave H.
    Dave H
  • GordyGordy Posts: 9,247Member
    edited February 27
    To give you an idea. My old home had ceiling, and floor radiant. 3/8” copper tube in plaster. 5000’ divided by 22 loops. So 227’ loops +/-. No zoning, and all driven by a Bell and Gossett PL 30. Each loop was seeing about .7 Gpm.
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