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Retrofitted radiant tubing

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smcc
smcc Member Posts: 4
in Radiant Heating
Recently installed "staple up" PEX tubing in existing first floor joist space and now discover that the thickness of the flooring is hindering the heat transfer. Floors are 2 1/4" thick wood or carpet combination. I'm only able to get floor surface temp to about 76 f.
Any solutions/suggestions?

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  • Brewbeer
    Brewbeer Member Posts: 616
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    Are you using heavy extruded aluminum plates?
    Hydronics inspired homeowner with self-designed high efficiency low temperature baseboard system and professionally installed mod-con boiler with indirect DHW. My system design thread: http://forum.heatinghelp.com/discussion/154385
    System Photo: https://us.v-cdn.net/5021738/uploads/FileUpload/79/451e1f19a1e5b345e0951fbe1ff6ca.jpg
  • bmwpowere36m3
    bmwpowere36m3 Member Posts: 512
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    76F is pretty warm for the floor, if it's wood you should limit it to 80F anyway. Is the radiant floor the only heat source?

    Are the bays insulated? Did you use plates? Extruded or stamped? Quickest and easiest would be to: increase supply water temp and/or GPM.
  • Gordy
    Gordy Member Posts: 9,546
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    Did you do a heat loss first? None of the fore mentioned will help if you need more output than 80-85* floor temp will yield for btus a square foot.
    jonny88Zman
  • smcc
    smcc Member Posts: 4
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    Radiant is the only source for that level of the house, first floor. All bays are insulated and heat transfer plates installed, spaced 6 - 12" apart. Water supply temp is at 140* . T-stat is set at 68 and has maintained that, although it seems the boiler runs a long time. Weather has been fairly warm. We had 2 days of 0* weather and wasn't able to maintain the 68*.
    considering supplemental fin tube, just not sure the best way to control it.
  • Gordy
    Gordy Member Posts: 9,546
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    You can bump the swt up a little. 150 -155see what happens
  • smcc
    smcc Member Posts: 4
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    I'll give it a try and let you know. thanks
  • bmwpowere36m3
    bmwpowere36m3 Member Posts: 512
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    As Gordy said, without doing a heat loss and estimating floor R-value... you won't know what floor temps are required and corresponding supply temps.

    Is this on ODR? While doing the calcs and stuff, just bump up the supply to 150F and see how it goes. For staple-up, I think, you can go up to 180F. Not ideal, but you'll have more heat. Then you can think about adding more emitters or reducing the buildings heatloss.
  • smcc
    smcc Member Posts: 4
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    ODR?
  • Gordy
    Gordy Member Posts: 9,546
    edited January 2016
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    Caution with the wood floors if finish surface your at 76* so do your adjustments incrementally and monitor.
    bmwpowere36m3Zman
  • Gordy
    Gordy Member Posts: 9,546
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    ODR is outdoor reset. It adjusts the water temps based on outdoor temps.
    bmwpowere36m3Zman

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