Radiant Panel Association

QUICK REFERENCE

to RPA Guidelines for Hydronic Radiant Floor Heating

Special Insulation Considerations

Location	Application	Min. 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
	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
	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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