Radiant Floor Heating Gary Hayden, P.E. ASHRAE Distinguished Lecturer
What is Radiant Heat? The Sun Camp Fire Wood Stove
Modes of Radiant Heat Convection Conduction Radiation
Heat loss Parameters Amount of Heat Lost to Cold R- Values Air Infiltration
Goal for Heating Heat loss = Heating Capacity
Surface Temperatures
Floor Surface Temperatures PERIMETER AREA Maximum Floor Surface Temperatures for Comfort Occupied Area 85 o F Perimeter Area 95 o F Outside Walls Bathroom 90 o F 3 OCCUPIED AREA
Perimeter Area Calculation 3 feet 20 Perimeter Area Calculation [25 x 3 + ((20-3 ) x 3 )] = 164 ft2 Occupied Area Calculation [(25 x 20 ) 164 ft2] = 336 ft2 25
Heat Transfer Coefficient
Floor Heating Output Calculation F o r m u Ol a u ftop Ca r ul tc u l a t i o n f o r R a d i a n t F l Btuh/ f 2 t = H x T ( C F l o o r S u r f o F a c Re ot oe m o p F T ) e m p H e a t T r a n s f e r C o e f f i c ti he / un f 2 t- o F o r ( UH 2 ste f C o r = q u1 i. c9 k 6 cb a l R o ote me pr a t ui s de r e s i rco e d m fle o vr t e l a or f o m ( T y p o if ctao l o l7f y 2) 6 5
Sample Calculation Results Floor Surface Temperature o F Room Temperature o F Output Btuh/ft 2 85 70 29.4 90 70 39.2 95 70 49
RFH Design Requirements Heat loss for Space Heat Production from Floor Installation / Floor Coverings Hydraulics Tubing and Circulators (Pumps) Heating Source Boiler Geothermal Solar Electric
Heat Loss for Planned Space
Heat Loss Numbers Component Length Width/Height Area ft 2 T o F R-value ft 2 o F/ Btuh Total Heat Loss Btuh Window 3 4 12 48 1.5 384 Wall 1 15 10 138 48 19 349 Glass Door 6 7 42 48 1.5 1344 Wall 2 10 10 10 66 48 19 168 Floor 15 10 10 162 28 * 19 240 Ceiling 15 10 10 162 48 38 205 Total Btuh 2,690
Heat loss Basics * C r a ws l p a c e T e m p e ra tu re e q o F u a ls 4 0 B tu h = (S u rfa c e A re T a ) */ R-v a lu e T = R o o m T e m p e r ao tuu rtd e o o r T e m p e ra t u re R e m e m b e r to s u b tra c t w in d o w a n d d o o r a re a fro m o u t s c a lc u la t e w a ll. a re a s A ir In filtra tio o f n1.5 x 2,6 9 0 = T o ta l H e a tlo s T o ta l H elo a ts s = 4,0 5 9 B t B a sic H e a t L o s s C a lc u la tiod n : M e th o 1 ) D e te rm in e th e a ir te m p e ra tu r e d i ffe r e n c e b e t w e e n o ut td. ou osr e ath n d e in d ed so ire o r, d in d o o r te m p o F e r) ale tusr s e th ( 6e 8 o u td o o r te m p e r a tu r e e x p e c te d o n th e c o ld e s t d a y o f th e y e a r. 2 ) M u ltip ly th e to ta l o u td o o r w a ll a r e a, l e s s t h e w i na dbo y w tha e nt d. dd oiv o r ida e reth is v a lu e b-v y ath lu e Rfo r th e w a ll. T y p ic a l w a lls h a v e a -vto a lu ta l e Ro f 1 9. 3 ) M u ltip ly th e to ta l w in d o w a re T a. bd y i vt hi de e th is v a lu e b-v y ath lu e Rf o r t h e w in d o w. T h e a v e r a g-v e ar lu e fo r a w i n d o w is 1.5. 4 ) D o th e s a m e hfo e r c et ilin g a n d th e f lo o r. T-v ya plu i ce as l ar r e 3 8 f o r c e ilin g s a n d 1 9 fo r flo o r s. 5 ) A d d u p th e h e a t lo s s f o r e a c h c o m p o n e n t t o d e te rm i n e th e t o ta l h e a t lo s s fo r th e ro o m. 6 ) M u ltip ly th e h e a t lo s s b y 1.5 t o a c c o m m o d a te ft o r c air lcin u la f iltra te t oe tit ao tlol n hs. s 7 ) D e te rm in e th e h e a t lo a d p e r flo o r h e a te d a re a r e q u i re m e n t b y d iv id in g th e to ta l h e a t lo s s b y th e f h e a t in g. R e m e m b e r th a t th e f lo o r a r e a th a t is c o v e r e d w ith c a b in e ts o r o th e r fix tu re s uwrc ill e. n o t b e
Available Floor Surface Area 15'-0" 8'-11 1/2" 10'-10 13/16"
Mean Heating Water Temperature Mean Heating Water Temperature = MHWT (Supply Water Temperature + Return Water Temperature) / 2 = MHWT Example: Supply Water Temperature = 110 of Return Water Temperature = 90 of MHWT = (110 + 90) / 2 = 100 o F
Circuit Lengths for RFH Circuit Lengths for ½ and 5/8 Nominal PEX ASTM F876/F877 1/2 PEX 300 ft. Recommended 350 ft. Maximum 5/8 PEX 400 ft. Recommended 500 ft. Maximum Reference: RPA Guidelines 2004 Edition Section 18.1.1
Pump and Pipe Tables
RFH Installation Methods Slab on Grade Joist Space Sub-Floor Installation
RFH Outputs by Type
Slab on Grade Floor Covering Concrete Slab Insulation Heating Pipe Ground or Structural Panel
Sub-Floor Installation F lo o r C o v e r in g H e a t in g P ip e L t. W e ig h t T h e r m a l M a s S u b F lo o r In s u la tio n F lo o r J o is t
Joist Space F lo o r C o v e r in g H e a t i n g P i H e a t T r a n s f e r P l a t e s S u b F lo o I n s u la t io n F l o o r J o i s t
Embedded Floor Installation F l o o r C o v e r i n g H e a t i n g P i p e H e a t T r a n s f e r P l a t e s W o o d D i v i d e S u b F l o o r I n s u l a t i o n F l o o r J o i s t
Heating Element Spacing Slab-on-gra de Cove ring R=0.00 MHWT - o F 1 5 0.0 0 1 4 0.0 0 1 3 0.0 0 1 2 0.0 0 1 1 0.0 0 1 0 0.0 0 9 0.0 0 Floor Surface Temperature o F 9 5 9 0 8 0 8 0 7 5 8 0.0 0 7 0.0 0 1 2 10 8 6 4 2 Pipe Spacing - Inches
Floor Coverings Type of Floor Covering Thickness of Floor Covering (inches) R-value (Btu/ft 2 - o F) * Max Exposure Temperature ( o F) Carpet Pad Slab Rubber.25.32 95 Oak Flooring.75.638 80 Ceramic Tile.25.25 125 Marble.5.4 100 Laminate Flooring.16.3 95 Carpet.5 1.4 100 Plywood.75.825 140 Linoleum.2.125 100 Cork.375 1.125 100 * Table Data is generic and should be verified by specified flooring manufacturer for each installation and design case.
Exposure Temperature o Exposure Temperature F 150 140 130 120 110 100 90 80 70 Exposure Temperature 1.00 1.25 2.00 0.75 1.75 0.50 1.50 0.25 95 90 85 80 75 70 Floor Surface Temperature - o F
RFH System Components Pipe Manifolds Fittings Accessories Controls Tools
Pipe ASTM F876/F877 - PEX c NSF-rfh ICBO ES ER 5421 PPI Listed DIN 4726 Oxygen Barrier
Manifolds Brass Copper Easy Assembly Proven Components Many Different Sizes
Fittings All Brass Construction Fully Tested and Certified NSF-rfh ICBO ES ER 5421 No Special Tools Required ASTM F877 Crimp Fittings Special Tools
Installation Accessories Labor Saving Back Saving Professional Installation Prevents Pipe Damage
Modern Controls Labor Saving Decreases Trouble Shooting Time Proven Service Record Improves System Performance Professional Installation
ASHRAE Handbook
Tools Decreases Installation Time Back Saving Professional Quality Eases Installation
Pump Injection
Pump Injection with HX
Thermostatic Mixing Valve
4 Way Mixing Valve
Resources for Design ASHRAE Handbooks Radiant Panel Association Manufacturer's Guides / Manuals
Questions