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Radiant under-floor system

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  • HomerJSmith
    HomerJSmith Member Posts: 2,737
    edited January 14

    @Alan (California Radiant) Forbes, tube to plate contact can make a big difference, I think. As thin plate heats up the expansion gap between plate and tube may increase lowering the effective heat energy transfer. The number of plates also would make a difference in how the floor responds as well as type of floor construction.

    I can see where heavier aluminum plates could transfer more heat energy because of the increased mass, might also minimize gapping between tube and plate.

    In seeking scientific truth all variables are controlled except the one that your testing for.

  • LMacNevin
    LMacNevin Member Posts: 22

    Sharing a few standard and code facts:

    ASHRAE Std. 55 "Thermal Environmental Conditions for Human Occupancy" mandates a maximum floor temp of 29C (85F) in occupied areas; perimeter areas are not covered by this and could be warmer if needed.

    IAPMO UMC and USHGC codes includes this limit plus higher floor temp limits for other areas. CSA B214 matches the IAPMO codes. These are maximums, if you need that much heat. It's better to spread the heat through more floor or wall area than to overheat the main occupied area.

    Extract from 2024 USHGC shown for reference:

    image.png
    bjohnhy
  • TAG
    TAG Member Posts: 799

    Doing a room by room heat load is a must — you have to understand what it required to heat the space. Then it's a question of seeing what the intended radiant system can deliver per SF

    I am a Warmboard guy — With wood flooring (even very wide) it works and does so at low temps.

    I did a project a few years ago and wanted to use one temp water based on what the Warmboard required to heat most of the house. There was one large room — over 1k sf that was not being changed and so was going to retain its finished flooring. I used the heavy plates as they had a higher BTU per SF at a given water temp. We used 3/8 tubing because I was able to fish it to that space. The only issue was the number of runs that I had to use to keep each at around 200 feet. I think I used a 10 or 11 zone manifold for that one room.

    HomerJSmith

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