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°F (60°C) max. in gypsum or concrete based thermal mass unless approved by manufacturer design and installation instruc tions.
160°F (71.1°C) max. underside of wood subfloor
180°F (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. |
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NOTE: This chart is for indoor radiant heating - not snow melting applications |
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Oxygen Permeation - Options:
Oxygen barrier tube, less than 0.1 gram/m3/day at 40°F
Heat Exchanger to isolate non-oxygen barrier tube
Water treatment to inhibit corrosion due to oxygen
