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01/09/2006 10:20 PM
I recently built an ICF home and installed radiant heat throughout the entire home under the sub floor using Wirsbo's Joist Trac. The house is extremely comfortable with one exception. The smallest room in the house which is a 175 sq ft office with 3 exterior exposure walls will not get to 69 degrees. The exterior walls are ICF (2 1/2" EPS x 6" conc. x 2 1/2"EPS). I have one circulator for this room and the total tube length is about 250 feet. The temp going to the room is 115 degrees and returning at 112. The spacing is 8 inches for the tubing snapped into the Joist Trac with a layer of foil buble foil and r-13 fiberglass insulation. The room below is the basement which maintains a constent temp of 67 degrees (in slab heat). Any thoughts why I cannot get to set point?

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01/16/2006 4:32 PM
Couple of things to look for/check.... 1. What size PEX are you using? Looking at my calc's, 175 sq.ft. room needs to have in the floor about 265' of tube and that doesn't count the leaders. 2. What is the finished floor construction above the Joist Trak? 3. Circulator size? 4. Is the insulation pushed up tight to the traks? It should be with the extruded plates. What you should also look for is the surface temperature of the floor, water temp is one thing, but the floor temp is most important for the heat transfer to occur. If you need to, just bump up the water temp. quote: Originally posted by berrycw I recently built an ICF home and installed radiant heat throughout the entire home under the sub floor using Wirsbo's Joist Trac. The house is extremely comfortable with one exception. The smallest room in the house which is a 175 sq ft office with 3 exterior exposure walls will not get to 69 degrees. The exterior walls are ICF (2 1/2" EPS x 6" conc. x 2 1/2"EPS). I have one circulator for this room and the total tube length is about 250 feet. The temp going to the room is 115 degrees and returning at 112. The spacing is 8 inches for the tubing snapped into the Joist Trac with a layer of foil buble foil and r-13 fiberglass insulation. The room below is the basement which maintains a constent temp of 67 degrees (in slab heat). Any thoughts why I cannot get to set point?

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01/17/2006 11:27 PM
Dave, Thanks for the response. I bumped the water temp 10 degrees and the room warmed up withn an hour and has been maintaing temp fine. I am using 1/2 pex in the extruded plates mounted under the subfloor. Thanks Chuck

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