Quick Reference

RPA Guidelines for Hydronic Radiant Floor Heating

Special Insulation Considerations

 Location

     Application

 Minimum R-Value

 Coverage

 Slab on Grade  Alternate # 1  (Ti-To) 0.125*  Perimeter to below frost line
   Alternate # 2  R-5  4' horizontal or vertical at perimeter
   Alternate # 3  R-5  under entire slab and slab edge
 Slab Below Grade    R-5 **  
 Suspended Floor  Over Heated Space Hard Surface  R-5 under entire floor with 2" air gap
   Over Heated Carpeted Surface  R-11 under entire floor with 2" air gap
   Over Unheated Space Hard Surface  R-13 under entire floor with 2" air gap
   Over Unheated Carpeted Surface  R-19 under entire floor with 2" air gap
Walls with Panels  Outside Wall  R-13 entire wall
   Inside Wall  optional  
 Ceiling Panels  Inside Ceiling  R-11 entire ceiling above panel
   Outside Ceiling  R-30 entire ceiling above panel

 
          *   R-value = Inside Temperature - Outdoor Temperature x 0.125 (temperatures in °F)
          ** For slab above frost line

Pressure Testing Embedded Tubing -
     100 PSI for at least 30 minutes
     Pressure reduced to 30 PSI before cement is poured.
     Refer to Section 12.1 and section 21.1.

Floor Surface Temperatures -
     85°F (29°C) max. in prolonged foot contact areas
     90°F (32°C) max. other than prolonged foot contact areas
     85°F (29°C) max. on solid or laminated hardwood flooring

Fluid Temperatures -
     140° (60°C) max. in gypsum or concrete based thermal mass unless approved by manufacturer design and installation instruc tions.
     160° (71.1°C) max. underside of wood subfloor
     180° (82.2°C) max. underside of wood subfloor when approved by tubing manufacturer's design methods

Floor Covering - R-value not to exceed design requirement

Tube Placement -
    
Structural Slab
          2" min. below surface, no tube joints in slab, sleeved a min. of 4" either side of expansion joint.
          Any repairs to tube damaged during pour shall be made with factory approved fitting and should be wrapped.
 
     Non-structural
          3/4" underlayment over highest point in tube
          1/8" min. gap between butt ends of aluminum plates no inaccessible tube joints
 
     Joist Space
          1/8" min. gap between butt ends of aluminum plates
          2" air gap below tube except where aluminum plates are used

Tube Length -

 Tube Size

Recommended

 Maximum

 1/4" I.D. tubing

 100 ft.

 125 ft.

  3/8" I.D. tubing

 200 ft.

 250 ft.

 1/2" I.D. tubing

 300 ft.

 350 ft.

  5/8" I.D. tubing

 400 ft.

 500 ft.

  3/4" I.D. tubing

 500 ft.

 600 ft.

 1" I.D. tubing

750 ft

 750 ft.

 

 

 

 NOTE: This chart is for indoor radiant heating - not snow melting applications    

Oxygen Permeation - Options:
    
Oxygen barrier tube, less than 0.1 gram/m3/day at 40°
     Heat Exchanger to isolate non-oxygen barrier tube
     Water treatment to inhibit corrosion due to oxygen

 

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