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Radiant Help

pghrich
pghrich Member Posts: 9


I built a new home two years ago and installed a lot of O2 pex pipe. I have a total of nine zones in both concrete and staple up plates. I'm using a 199 BTU instant water tank to run it. All my concrete areas run fine and retain heat fine. The areas that I'm having issues is the areas that have the staple up plates. I have two runs in each bay with all run kept as close to 300' as possible. These areas consist of a (4) port, (3) port, and a (8) port manifold. right now, these areas have a mixture of both carpet, tile, and lots of hardwood flooring. I was told to use the staple up metal faced bubble wrap as the insulation since the basement below was climate controlled.

The problem that I'm having is that these areas don't feel warm to the touch and see to run quite a bit to maintain. Leads me back to what i believe is the issue. The installer that did the final connections used a 1" copper line to connect all the taco pumps together (supply and return). There is a 3/4" copper line coming off the boiler.

I had another company look and they said that I don't have enough flow and need to remove all the supply / return lines and reinstall 2" copper in its place along with installing a buster pump.

The two items that I have in question are - Do I need R19 insulation with metal facing install in the floor
trusses or is the bubble wrap fine. No i not have enough flow.

Any help would be appreciated. Thanks.

Comments

  • kcopp
    kcopp Member Posts: 3,990
    Yes you need more insulation. Bubble foil is not really insulation its packing material. Get a minimum of r-19 up in there.
    Also the Water heater was not a great choice to heat the water. Its a water heater. A boiler is really what you need. If you want to have a better change of that working it needs to be re-piped...primary (boiler loop ) w/ the supply and return to the system off that primary loop.
  • pghrich
    pghrich Member Posts: 9


    This is what was used. Are you saying that I need a primary secondary loop?
  • EzzyT
    EzzyT Member Posts: 1,202
    Yes you need more insulation underneath that tubing and that tankless water heater isn’t designed for heating plus if you where going to swap out the tankless with a wall hung boiler I would definitely add a buffer to add more mass to reduce any short cycling that will occur and the buffer tank will take care of your primary/secondary piping. Or go with a high mass high volume unit like the HTP Pioneer which doesn’t need to be pipe primary/secondary.
  • pghrich
    pghrich Member Posts: 9
    Does the insulation need to be foil backed with a 2" gap or can I use R19 and push it right up to the plates that are screwed to the sub floor?
  • Zman
    Zman Member Posts: 7,334
    Is the tubing installed with aluminum plates or is it just stapled to the plywood?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • pghrich
    pghrich Member Posts: 9
    It is installed with 4’ aluminum plates. Two rows in each bay running the full length.
  • Zman
    Zman Member Posts: 7,334
    I would recommend doing a heat loss and studying this.
    The boiler piping is obviously incorrect. More insulation would also help.
    I am wondering whether or not you need a 2 temp system that also limits the amount of heat the slabs can gobble up.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • pghrich
    pghrich Member Posts: 9
    What is incorrect about the piping? One company told me that it needs to be switched to primary/secondary loop system. Is this what your referring to?
  • Zman
    Zman Member Posts: 7,334
    The common piping is way undersized and will cause some zones to starve when everything is running. Tankless water heaters are not intended for heating. They have very high head loss. Primary/secondary is a good idea to overcome this.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • hot_rod
    hot_rod Member Posts: 16,345
    8 circulators, oh my aching back :) 640W to move how much load?

    I'd start with a heat load calc, room by room. Then a design analysis to assure the heat load can be covered with radiant.

    Youn can do a load clc yourself or hire one of the designers on this site to at least do a correct load/ design.

    Then and only then should you select components and start piping.

    Sort with step one if you want to sort this out with one attempt.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    ZmanSuperTechCanucker
  • HomerJSmith
    HomerJSmith Member Posts: 1,567
    As said you need more insulation to prevent back-loss. You need to keep the insulation 2" below the pex. You need that air space, so don't put the insulation tight against the sub-floor.
    Rich_49
  • hot_rod
    hot_rod Member Posts: 16,345
    If it is a transfer plate install, no problem pushing insulation up against it, the more R the better. It is all conduction transfer. We spray foamed plenty of plate installs.

    Sealing joist bay ends is critical to prevent infiltration and that is your higher ∆T area. Spray foam is ideal for that also.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Rich_49
  • HomerJSmith
    HomerJSmith Member Posts: 1,567
    The reason for keeping the insulation 2" below the heat transfer plate is to minimize banding, but if you have two transfer plates in a 16 o/c bay, then putting the insulation against the floor would be ok.