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Radiant setup for fully poured concrete home

deconcreter
deconcreter Member Posts: 13
edited August 2019 in Radiant Heating
Hello all, I found this website when doing some research on a radiant hydronic setup that I have started building. I am looking for feedback and thoughts before I make any final decisions. I will just start with pictures to make things easier to understand as it is quite an unorthodox configuration for radiant heat.

Bathroom



1st Bedroom



2nd Bedroom (will be used as clothing storage instead of bedroom indefinitely)



3rd Bedroom



Now to explain what's going on here: you are looking at a second floor of a concrete home, with 10" thick reinforced concrete floors. When speaking to local professionals, it seemed that I would have issues doing a radiant in slab installation and so I devised this system instead. It's 2" rigid foil backed foamboard insulation with 2x4's @ 16" spacing to create a subfloor. I was initially planning on running 1x 1/2" pex tube per field but I am worried that with this unorthodox system that I will not be getting the heat transfer that I would get if I was using a more traditional staple-up aluminum plate system. Obviously with the concrete floor that is not possible anyway, and so I wanted to see what considerations I should take before moving forward with the install. My plan is now to run Raupanel every 16" in between the fields with something underneath to butt it up against the hardwood.. The bedrooms will be 3/4" solid hardwood flooring, and I was hoping to run tile in the bathroom. Underneath the bedrooms is unheated garage space/shop rooms, which obviously pose an issue, but I intend to work a heating system into there shortly.

Open to any and all suggestions, feedback, and critique.

Thanks

P.S. Here is a photo of a heat loss calculation I've done. I'm not sure if the results are accurate and would like somebody to double check them if possible.

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Comments

  • Zman
    Zman Member Posts: 7,561
    Have you considered stapling the tubing to the foam and pouring gypcrete?
    I can't picture how you will get the transfer plates to make good contact with the substrate with you present plan.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • deconcreter
    deconcreter Member Posts: 13
    edited August 2019
    Zman said:

    Have you considered stapling the tubing to the foam and pouring gypcrete?
    I can't picture how you will get the transfer plates to make good contact with the substrate with you present plan.

    Okay so initially this was the plan, problem being it was cost prohibitive in my area to get a concrete pump (I think that's needed for the volume necessary to cover 1500 sq ft on the second floor?) It is somewhat ironic that had I just committed to going down that route I would have probably broke even with this idea with the Raupanel. At this point in time I think I would lose too much height from pouring gypcrete and I also am hesitant to go around ripping out 6-700 tapcons that I painstakingly installed. Feel free to call me out if there's any flaws in my logic.

    Then I considered stapling the pex to the sides of the 2x4's in the pictures, with 2 runs per field. My concern with this is that I might just be better off with one run per field, but in the plates with much more contact area.

    Let me ask you this, where do you see a problem with getting the transfer plates to contact the hardwood? The raupanel is 5/8" thick and so I was considering running 7/8" finish board perpendicular to the plates to provide the support and push them up.
  • hot_rod
    hot_rod Member Posts: 22,020
    9784 btu/hr load in a 1500 sq ft room. Should be fairly easy to cover that load with your plan. You could probably staple pex to the side of those sleepers and get 7 btu/ ft output :) bare tube staple up is good for 10- 15 btu/ft.

    I would pack more foam under the Raupanel to push it up against the floor if possible, if you go that route.

    I don't worry so much about even floor surface temperature in bedrooms. Much of the floor is covered with furnishings so foot comfort is not a priority. It's more about covering the load.

    I'd tube the bath at 6"-8" oc or use transfer plates. With tile surfaces you notice the striping of wide tube spacing.

    The loops in the 3 rooms should be manifolded so you can balance, if this is one zone?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Zman
    Zman Member Posts: 7,561
    I have done many installs where gyp is poured around what you have down right now and wood floor is laid on top. Just 1 1/2" of gyp works great.

    In areas where gypcrete is common, the installers have a flatbed truck with sand and gyp on the back. They tow a small trailer pump/mixer and just mix on site. Gypcrete is often used for fire assemblies in commercial buildings. There may be a contractor in your area that is set up to do this.

    Hot rod makes a good point that you probably don't need that much transfer with your low loads. Do be sure to attach everything well. I have been in homes where it sounds like you have snakes under the floor when the heat comes on. Pex expands and contracts significantly.This is less of an issue with PEX-AL-PEX.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • deconcreter
    deconcreter Member Posts: 13
    edited August 2019
    hot_rod said:

    9784 btu/hr load in a 1500 sq ft room. Should be fairly easy to cover that load with your plan. You could probably staple pex to the side of those sleepers and get 7 btu/ ft output :) bare tube staple up is good for 10- 15 btu/ft.

    I would pack more foam under the Raupanel to push it up against the floor if possible, if you go that route.

    I don't worry so much about even floor surface temperature in bedrooms. Much of the floor is covered with furnishings so foot comfort is not a priority. It's more about covering the load.

    I guess my concern is maximizing the effective output, as I am adding on another 2500 sq ft and would prefer to use radiant throughout the house. Sort of future-proofing, in a way? Regardless, I will have to pick and choose my battles and it may be a better investment to put that Raupanel in more commonly used living spaces ie. living room and kitchen/dining area.
    hot_rod said:

    I'd tube the bath at 6"-8" oc or use transfer plates. With tile surfaces you notice the striping of wide tube spacing.

    The loops in the 3 rooms should be manifolded so you can balance, if this is one zone?

    Good tips here, I will likely alter the layout in the bathroom as I currently have it set to run under the sinks, which I've found is a big no-no and a waste of energy. For the tile in the bathroom, maybe I can use Raupanel and get rid of the 2x's, with a layer of Kerdi directly on top? (thread for reference: https://forum.heatinghelp.com/discussion/124941/raupanel-install)

    As far as the loops, I am in a bit of a pickle, I was going to run 2 for bedroom #3 plus a small landing and 1 loop for the rest of the rooms. That leaves me with 5 loops, but I am unsure as to whether I can leave them all in one zone. I am of the understanding that if using plates and tile only in the bathroom, it would naturally be the warmest surface.
    Zman said:

    I have done many installs where gyp is poured around what you have down right now and wood floor is laid on top. Just 1 1/2" of gyp works great.

    In areas where gypcrete is common, the installers have a flatbed truck with sand and gyp on the back. They tow a small trailer pump/mixer and just mix on site. Gypcrete is often used for fire assemblies in commercial buildings. There may be a contractor in your area that is set up to do this.

    Hot rod makes a good point that you probably don't need that much transfer with your low loads. Do be sure to attach everything well. I have been in homes where it sounds like you have snakes under the floor when the heat comes on. Pex expands and contracts significantly.This is less of an issue with PEX-AL-PEX.

    I do not want to shoot down your idea of Gypcrete but it doesn't sound very enticing. I've lately read that Gypcrete almost has some insulative properties that can inhibit the heat transfer, on the other hand I would believe the thermal mass probably holds heat much better than the subfloor with open air. The other problem being, I have simply not been able to find local businesses familiar with lightweight concrete for residential settings. I think the nearest company was over an hour away and it showed in their price quotes.


    So far I've received some really great feedback and I truly appreciate it, thank you both.

    Edit: I have two big mixers, how bout I just mix some gypcrete up and pour it myself?!
  • hot_rod
    hot_rod Member Posts: 22,020
    I have mixed gyp in 5 gallon buckets before, for a small repair

    For that matter a pea gravel concrete mix works as well as gyp, much cheaper
    Although it doesn’t flow like gyp
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Zman
    Zman Member Posts: 7,561
    Gyp is tried and true in my area. Mixing it yourself makes good sense if you have the manpower. The price of radiant plates adds up pretty quick. Concrete would work if you are comfortable leveling it. Stay away from the lightweight concrete with foam pellets mixed in as it will insulate.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • hot_rod
    hot_rod Member Posts: 22,020
    I'd also stay away from gyp in areas that might get wet, like bathrooms. Any water on gyp, even with a sealer and it turns into wet sheetrock :)

    Gyp is ideal for fire and soundproofing, which is what it was intended for. Adding tube turns it into a radiant panel :)
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Zman
    Zman Member Posts: 7,561
    The durability of gypcrete really depends on the mix. I have seen older gyp with weak mix turn to kitty litter under carpet. Recently worked on a house that had flooded and the gyp was perfect.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • nibs
    nibs Member Posts: 511
    Oh man, so sad you did not embed the pex in the slab, what a wonderful opportunity for thermal mass. My build is very high thermal mass and it performs beautifully. perhaps you could fix the pex on top of the concrete then put a thin slab on top of the thick slab. We are tiling over our radiant slab and it is great. Today outside temp was 85 and the interior temp never went above 72. We have most interior walls made of cement and tilted up, 12"X12" concrete columns as much as16 ft high two foot thick North wall, east wall is 1'6" thick. I was showing a friend late this after noon that all my interior surfaces were 72F +/- except the floor slab which was 67F.
    Your concrete house will act like a flywheel absorbing warmth and emitting it as the air cools, but you already know this.
  • Zman
    Zman Member Posts: 7,561
    He has not poured the floor yet, it's not too late.....
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • nibs
    nibs Member Posts: 511
    My read is that his suspended slabs are done.
  • deconcreter
    deconcreter Member Posts: 13
    edited August 2019
    nibs said:

    Oh man, so sad you did not embed the pex in the slab, what a wonderful opportunity for thermal mass. My build is very high thermal mass and it performs beautifully. perhaps you could fix the pex on top of the concrete then put a thin slab on top of the thick slab. We are tiling over our radiant slab and it is great. Today outside temp was 85 and the interior temp never went above 72. We have most interior walls made of cement and tilted up, 12"X12" concrete columns as much as16 ft high two foot thick North wall, east wall is 1'6" thick. I was showing a friend late this after noon that all my interior surfaces were 72F +/- except the floor slab which was 67F.
    Your concrete house will act like a flywheel absorbing warmth and emitting it as the air cools, but you already know this.

    Yes, embedding pex in the suspended slab during the first pour would have been optimal. I intend to do it during the next phase on the next addition, but I am stuck now trying to work around it.

    For the sake of clarity, all of the concrete has been poured on my first phase. If I would pour gypcrete now it would be on top of the foamboard which is on top of the suspended slab. Wouldn't pouring the gypcrete directly on top of the slab emit too much heat to the unfinished garage downstairs?

  • Zman
    Zman Member Posts: 7,561
    He can still do a thin gyp slab over the insulation and between the sleepers. IMO this is the best of both worlds. The massive structural slabs are isolated and the radiant is at the top.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • deconcreter
    deconcreter Member Posts: 13
    edited August 2019
    I posted a comment responding to @nibs but it seems to have disappeared into the void. The suspended slabs are already poured, and I was worried I would be losing heat into the garage underneath because it is not yet heated.

    At this point I'm still leaning towards plates in each field. Won't I still gain some advantages from the thermal mass of the concrete once the air in the home is heated to a constant temperature? I also found THESE plates, which are less than half the cost of the Raupanel for double the surface area. Now they are .024" thick vs .06" thick for the Rehau product, but I'm not convinced the thickness difference is more efficient than the increase in surface area provided by the RHT plates.
  • nibs
    nibs Member Posts: 511
    @deconcreter , I defer to more knowledgeable people than I, but I suspect if you put the pex directly on top of the suspended, you may not need to heat the garage. With 10" of cement between the garage space and the pex , the lid would be a radiant ceiling with most of the warmth going into the residential space above. Once you get that concrete warm, given sufficient exterior insulation your boiler will be lazing along in the coldest weather.
  • deconcreter
    deconcreter Member Posts: 13
    edited August 2019
    @nibs While a majority of the concrete is very well insulated, there are still exposed exterior areas that are connected to the main suspended slab without any thermal breaking between them. This is why I went crazy and installed 2" of foil backed foam on the floor.
  • hot_rod
    hot_rod Member Posts: 22,020
    I don't think tat 10" slab would be a friendly radiant emitter, way too much mass to ramp up and down. Your plan to pour or build on top with some R value between is a sound one.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • nibs
    nibs Member Posts: 511
    @deconcreter What I bring to this site is years of general contracting and experience with some innovative forms and uses of concrete, I defer to the experienced heads here such as @hot_rod who have taught me much about hydronic radiant.
    Too bad that the suspended is not edge insulated, though it would be rather difficult to engineer. Are your walls ICF, I wish the stuff had been less expensive when we started I would have used it more extensively. I am a firm believer in putting the insulation on the outside of the building, to build thermal mass on the inside, can you insulate the suspended on the outside of the walls?. When you pour the SOG, be sure to insulate the underside I personally like Dow Roofmate, it is 2x4 by 4" thick with stepped edges, wont take on water, quite high psi and easy to install.
  • deconcreter
    deconcreter Member Posts: 13
    edited August 2019
    @nibs No, ICF wasn't around regionally when we started pouring. This project took a long break before I took over to finish it. It was all poured with homemade forms using plywood and 4x4's. Lots of blood, sweat, and tears. The slab-on-grade has been poured from day one so whatever is under there is under there. Fortunately we have an access point to see under the slab from inside so I have planned on checking what is under the slab.

    Edit: Talking to my plumber tonight, I should be ordering the RHT plates 12 1/2" x 24" double "UU" style shortly. http://www.blueridgecompany.com/radiant/hydronic/316/rht-heat-transfer-plates
    Planning to rip strips of 1 1/2" XPS and glue under the middle and outside to provide some support underneath the plates and fill up some space. Not exactly the method I wanted to take but I feel it should work well and won't be as damaging on the pocketbook as the Raupanel.

    Next question, to ply or not to ply, under the 3/4" hardwood after I install the radiant. I ordered enough 15/32's ply to cover the floor. It seems to have an R-Value of around .58-.61. I haven't yet ordered the flooring. I was leaning towards 3/4" hardwood but I'm sure there's some other options.
  • hot_rod
    hot_rod Member Posts: 22,020
    Look into the engineered flooring. it is more stable, usually less thickness and can often be floated so repairs, expansion etc are handled

    Go with a brand that is all wood, not Masonite core.

    I used an Anderson brand, all the plays are oak, great finish. It’s been flooded 3 times in 21 years and still looks good. 2.5 wide, 5/16 thick T&G with micro bevel to clean up the seams. We glued it to a slab, radiant.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • nibs
    nibs Member Posts: 511
    @hot_rod, man engineered flooring sounds great, these ol' knees are getting so tired of tiling.
    @deconcreter, how is the concrete part of the exterior insulated?
  • hot_rod
    hot_rod Member Posts: 22,020
    nibs said:

    @hot_rod, man engineered flooring sounds great, these ol' knees are getting so tired of tiling.
    @deconcreter, how is the concrete part of the exterior insulated?

    I did a home that used a wood flooring that looked like tile, there are all sorts of finishes available on engineered products. Mine has an aluminum oxide, baked on finish, hard as glass.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • deconcreter
    deconcreter Member Posts: 13
    nibs said:

    @hot_rod, man engineered flooring sounds great, these ol' knees are getting so tired of tiling.
    @deconcreter, how is the concrete part of the exterior insulated?

    Foamular foamboard on top of foam board on top of foam board. If I recall, I have between 4-6 inches on the exterior walls and 3 inches interior. The house has a giant rock wall about 60 ft high protecting the northern wall and it really buffers northeastern winds. It's beneficial in harsh winter storms keeping the wind from ripping though our land. We also have a lot of tree cover and so it's definitely not enduring the worst of the weather like other houses in the area (mostly in open fields with forests few and far between.)

    @hot_rod I will look into engineered flooring. How is it from the reconditioning side of things? Is there a need for a buff and wax every so often or does it hold up?
  • hot_rod
    hot_rod Member Posts: 22,020

    nibs said:

    @hot_rod, man engineered flooring sounds great, these ol' knees are getting so tired of tiling.
    @deconcreter, how is the concrete part of the exterior insulated?

    Foamular foamboard on top of foam board on top of foam board. If I recall, I have between 4-6 inches on the exterior walls and 3 inches interior. The house has a giant rock wall about 60 ft high protecting the northern wall and it really buffers northeastern winds. It's beneficial in harsh winter storms keeping the wind from ripping though our land. We also have a lot of tree cover and so it's definitely not enduring the worst of the weather like other houses in the area (mostly in open fields with forests few and far between.)

    @hot_rod I will look into engineered flooring. How is it from the reconditioning side of things? Is there a need for a buff and wax every so often or does it hold up?

    Vacuum or mop is all we have done, no re-finishing. It did fad a bit as seen when we pulled up area rugs.

    Although we did wet vac a few times when it flooded :)

    https://www.flooring.org/Anderson-Flooring
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • nibs
    nibs Member Posts: 511
    @deconcreter If you have 4 to 6 inches of foam on the exterior where the suspended ties in, then it is pretty well insulated, so your suspended is edge insulated.
    I do not understand the interior insulation on the walls, our interior side of our concrete walls are bare and painted, and work very well as thermal mass. Until someone tells me I'm wrong, I feel you can never have too much fun or too much thermal mass.
  • Zman
    Zman Member Posts: 7,561
    Thermal mass is good. It does a nice job of averaging day and night temps to give you a comfortable home. When it is 50 at night and 85 during the day, the mass averages it out and life is good.
    Overheated thermal mass is bad deal. If you get a giant mass up to 80 degrees during a heat call at night, the next day the sun comes out and you are living in a sauna. You really can have too much of a good thing, especially in areas where the day/night temps swings are extreme and solar gain is high.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • hot_rod
    hot_rod Member Posts: 22,020
    nibs said:

    @deconcreter If you have 4 to 6 inches of foam on the exterior where the suspended ties in, then it is pretty well insulated, so your suspended is edge insulated.
    I do not understand the interior insulation on the walls, our interior side of our concrete walls are bare and painted, and work very well as thermal mass. Until someone tells me I'm wrong, I feel you can never have too much fun or too much thermal mass.

    When you do a heat load analysis for example. That is just a snapshot in time for that exact set of conditions. Temperature outside, infiltration, internal gains, building use patterns can change second by second. It's possible the building would never be under those exact conditions that you input to the load calculation.

    I've yet to see many heat load calc that takes into account internal gains, cooling load calc do. In super insulated homes the lighting, appliances, cooking, humans could conceivably warm the space, without any additional heat input, yet we still do a load and heat them to that number. Internal gains, like solar gains can over-heat a space, high mass may not handle conditions like that well.

    With a high mass you cannot make necessary corrections quickly. So in areas with frequent and wide temperature swings high mass can be a challenge to control to optimum comfort levels.

    Storage has always been the holy grail of thermal energy. Ideally excess energy could be "bottled up" stored and used when required. Large vessels with water or phase change, well insulated would be a better approach, but the $$ makes it out oil the question for most.

    If you believe in climate change the heating and cooling industry will see further challenges designing comfortable spaces. Design a cooling system to maintain comfort when outdoor temperatures reach 100°F and higher, 120F plus in Death Valley is not uncommon now for months at a a time. Now you are looking at a 45° or more ∆!
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • nibs
    nibs Member Posts: 511
    @hot_rod,
    @Zman
    We have no air conditioning, to manage interior daytime temps we open one or two clerestory windows and one or two bedroom windows at night, close them up about 1 hour after sunrise. Works very well, visitors are amazed at how cool we stay. Most of the windows only receive direct sun from Oct to March In the heating season we set the thermostat to 68 deg and leaveright there, often have a fire for the cheeriness starting in fall.
    Anyroad, back to putting tiles on the radiant floor argh.
  • hot_rod
    hot_rod Member Posts: 22,020
    nibs said:

    @hot_rod,
    @Zman
    We have no air conditioning, to manage interior daytime temps we open one or two clerestory windows and one or two bedroom windows at night, close them up about 1 hour after sunrise. Works very well, visitors are amazed at how cool we stay. Most of the windows only receive direct sun from Oct to March In the heating season we set the thermostat to 68 deg and leaveright there, often have a fire for the cheeriness starting in fall.
    Anyroad, back to putting tiles on the radiant floor argh.

    Sounds like you imagined, designed and built exactly what you wanted :) Energy efficient to boot. Mission accomplished!

    The beauty of hydronics, for me, is the unlimited amount of options. The ability to customize to the individuals needs and wants.

    Also somewhat forgiving if you do need to change the plan. For example a thin, wood, low mass system could be applied over a slab if the next owner of your home had different radiant ideas in mind.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • deconcreter
    deconcreter Member Posts: 13
    edited August 2019
    I think you all agree insulation on much of the structure is thorough, but when you question the interior insulation I must add, there are areas that were done previous to my current oversight and so I am only confident about what I have done myself. For example, I do not know to what extent, if at all, the SOG has been insulated. I actually will soon be digging down next to the foundation to get a better look with what I am working with, as well as from the interior access point in the garage area to make sure of what is really going on under there.

    Much of the insulation I have done thus far is very much because of what is unknown, and so I have not been completely confident that the mass upstairs will hold heat given that the slab downstairs may be drawing heat right out of the structure. This is the reason for interior insulation efforts. I am of the opinion that the temperature of the concrete can remain somewhat unchanged and just provide residual heat/cooling to the home despite interior insulation. I may be incorrect but I feel like it must have some effect.

    This is really a great dialogue we have going on here @nibs @hot_rod @Zman. I appreciate all the positive thinking as I've encountered a lot of resistance with local small-town contractors etc. when looking for advice and consultation. It sometimes can feel like I've done everything backwards but there are glimmering moments where I'm certain it's a unique yet solid method of construction. As you can tell this project has a lot of my heart and soul into it and it's great to have other people to talk to who are fanatics about this stuff as well. Thank you all again and I look forward to keeping in touch throughout this build.
  • hot_rod
    hot_rod Member Posts: 22,020
    Lack of, or poorly applied insulation really translate into energy cost to condition the home. Even un-insulated homes can be kept warm and comfortable.

    Certainly do all you can to upgrade. The edge loss is a huge number. With no earth contact, you work against ambient air to interior temperature ∆T. Below 0 temperature outside, trying to maintain 70 inside, without adequate insulation, ouch! What was in your wallet?

    That being said, Alberta had to back down from their required 4" under slab insulation requirement as it brought radiant slab jobs to a screeching halt. You could have upwards of 2 bucks a square foot just in under slab insulation, plus edge detail down 4'! That put radiant jobs in a fairly $$ rarified market.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • deconcreter
    deconcreter Member Posts: 13
    So I did some digging today, in the literal sense, and am led to believe I'm working with a 2' thick slab on bedrock, with no insulation in the mix at all. Nice to finally know for sure but curious how this will affect everything. Eventually I will have to put heat in the garage, but will I be doing slab>insulation>radiant pex>poured concrete or slab>insulation>poured concrete with other methods to heat the garage? I would really like to bring up the temperatures downstairs while keeping the concrete floor.
  • hot_rod
    hot_rod Member Posts: 22,020
    A portion of the heat energy will go down into the earth. Hot travels to cold, always. As long as the ground below is colder some heat, and $$, will transfer down. How much depends on how much temperature difference. The greater the delta, the more transfer. Probably not an ideal way to heat, an uninsulated slab.

    Radiant over builds, radiant ceilings, radiant walls, are options if you want radiant emitters.

    Panel rads, fin tube, hydronic wall heaters are other options.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • nibs
    nibs Member Posts: 511
    @deconcreter
    insulation>radiant pex>poured concrete or insulation>poured concrete with other methods to heat the <garage?.
    Either way needs to be compatible with the rest of the system, since we are still in the honeymoon phase with our radiant slab, and since you are doing radiant floors above, my gut is that your first option will fit what you are doing throughout. But recognize that people like @hot_rod have infinitely more experience than I with all kinds of hydronic systems. It would not impact the price of the work very much if you laid the pex yourself in the slab on slab even if you decided later to go a different route.
  • deconcreter
    deconcreter Member Posts: 13
    hot_rod said:

    A portion of the heat energy will go down into the earth. Hot travels to cold, always. As long as the ground below is colder some heat, and $$, will transfer down. How much depends on how much temperature difference. The greater the delta, the more transfer. Probably not an ideal way to heat, an uninsulated slab.

    Radiant over builds, radiant ceilings, radiant walls, are options if you want radiant emitters.

    Panel rads, fin tube, hydronic wall heaters are other options.

    I could just mirror what I did upstairs to the suspended slab, as it was fairly easy for me and not very expensive. But instead of running the 2x4 sleepers I would definitely use thinner firring strips to save money on buying 5" length tapcons; for the 1st floor shop room, office room, and bathroom (under the closet space, bed room, and bathroom, respectively.)

    These spaces could be used sparingly or very often. There is also an opportunity to use a wood stove underneath the 2nd floor bathroom! I have a storage space that has the chimney going right through it, where I have used a wood stove years previous. This could provide some supplementary heating to the office perhaps?

    Finally, in speaking to some friends I learned a bit about these electric and radiant panel radiators. It seems like a quick way to get some heat into the garage, but I'm more concerned about keeping a cooler and consistent temperature without using too much energy. For a few hundred dollars of pex in the slab and hooking it up to a manifold, I could keep it simple and use the same set up throughout. This is not a sticking point for me, I am absolutely open to the other options that you mentioned, but wonder how the other options provide benefits to a space like a garage.
  • hot_rod
    hot_rod Member Posts: 22,020
    If you want a fast heat delivery in the garage a hydronic unit heater would be one choice.

    If you plan on spending some time out there a radiant floor or ceiling would be quiet and comfortable.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • deconcreter
    deconcreter Member Posts: 13
    Thanks for the ideas @hot_rod.

    So here's where I am, attaching a video of the build so you guys can see what's going on.

    https://youtu.be/e8prRLdv7Nw

    There's nothing holding down the plates at the moment, not sure if that's going to be an issue after I put plywood down on it. I wanted to see where the loop ended up after running it from the proposed manifold location, and it looks like the return will not make it back. This is a 300ft loop, I know that that's supposed to be near the boundaries of a 10* Delta-T so not really sure where to go from here. I've read that increasing the Delta-T can allow me some more room, by about 30ft per degree increase, but this is really where my experience is lacking.

    The bends are also extremely ugly and twisted, but I don't think I'll be able to router ply where the bends cross over. Could I use snap in pex attachments that twist into the foam to add some support for the bends? I'm thinking that with the plywood on top, snaps for the pex, and heating it up will allow the twists to mellow/straighten out.
  • deconcreter
    deconcreter Member Posts: 13
    Hiya @hot_rod @Zman @nibs, hope all is well, interested to hear some feedback on my latest progress. Just waiting for some more pex and insulation to be delivered before I move on.
  • nibs
    nibs Member Posts: 511
    How short of home are you?
    You can warm the pex with a heat gun /hair dryer to tighten the curves, I have some tight 90deg bends to hold the pex you can have for the cost of shipping, they are pretty tight curves and difficult to use without kinking the pipe may have about 20 pcs. I started using them but pretty much abandoned them because I got some 3" styrofoam with cast in clips and also used plastic staples to hold the pex to flat styrofoam. Had one run that would not quite get back to the manifold but it did reach the floor opening so just added about 2 feet of pex with the join accessible if it should fail, it is a little bit ugly because it has to cross all the other runs, instead of lining up in order.