10 june 2014©uponor1 snow melting systems. 10 june 2014©uponor2 why snow melting ? safety garage...

10 April 2023 ©Uponor 1

Snow Melting Systems

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Why Snow Melting ?

Safety Garage ramps, driveways Sidewalks, bldg. entrances Emergency exits Reduced maintenance cost No shoveling, no plowing No salting

Extended surface life Carpets and tiles in the buildings Concrete, interlock stones Surrounding landscaping

NO LITIGATIONS

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Snow-Melt Design/Performance

CL1 Residential (Ar = 0) 120 Btu/sqft/hr load Semi-auto / manual controls 9” o.c.

CL2 Type Commercial/Public (Ar= .5) 150 Btu/sqft/hr load 9” o.c. Automatic controls

CL3 High safety areas (Ar = 1) upper range of 200 Btu/sqft/hr 6”o.c. Automatic controls /idling option

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Variables Affecting Load Design?Environmental Factors

Snow fall rate Wet or fluffy/dense snow Snow temperature Outside temperature Wind conditions

Per ASHRAE Applications Heat Flux for City To 95% of heat flux Snow free area ratio 1, 0.5, 0.0(0=snow cover=no

wind effect)

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Snow Melt Heat Balance

q= qs+qm+Ar(qh+qe) q heat flux required at surface qs sensible heat flux

qm latent heat flux (melting snow)

Ar snowfree area ratio

qh convective and radiative heat flux, after snow has melted

qe evaporative heat flux

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Snowmelt Design p.41

• Step 1- Identify the outside air temp. and wind speed• Step 2- Identify Delta T for system design• Step 3- Select design surface temp.• Step 4- Determine btu/sqft• Step 5- Determine supply water temp.• Step 6- Identify the installation area • Step 7- Determine btu/h requirements (boiler sizing)• Step 8- Determine type and size of tubing• Step 9- Determine the amount of tubing• Step 10- Determine active loop lengths and # of loops• Step 11- Determine total loop length with leader• Step 12- Select percentage of glycol• Step 13- Determine gpm• Step 14- Determine system gpm • Step 15- Determine system pressure drop

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Design parameters

•Design temp. = 5F•Wind speed = 10 mph•Surface temp. = 38F•1700sqft driveway•5/8 MultiCor

Appendix A – worksheet p. 61

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Snowmelt design

• Step 1- Identify the outside air temp. and wind speed

• Step 2- Identify Delta T for system design• Step 3- Select design surface temp.

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Snowmelt design• Step 4- Determine btu/sqft/hr• Step 5- Determine supply water temp.

Appendix C – Page 66

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Snowmelt design

• Step 6- Identify the installation area -Ex. Sidewalk 17ft x 100ft = 1,700 sqft

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Snowmelt design• Step 7- Determine btu/h requirements (boiler sizing) Ex. Sidewalk

-126 btu/sqft x 1,700 sqft = 214,200 btu/h• Step 8 - Determine type a size of tubing

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Snowmelt design• Step 9- Determine the amount of tubing 1.33 x 1,700 = 2,261• Step 10- Determine active loop lengths and # of loops 2,261 / 200 = 11.3 loops ( ~12 loops) or 2,261 / 11 = 206 ft per loop

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Snowmelt design

• Step 12- Select percentage of glycol Ex. Sidewalk we selected 40% glycol

mixture

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Snowmelt design

• Step 13- Determine gpm

Appendix C, p70

206 ft x 0.0081 = 1.67 gpm per loop

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Snowmelt design• Step 14- Determine system gpm 1.67 gmp/loop x 11 loops = 18.37 gpm• Step 15- Determine system pressure drop

0.03090 x 226 = 7.0 ft of head

Appendix E, p85

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System Design

TYP. SYSTEM

Outdoor Air Temp - 0 °F Wind Speed - 10 mph Fluid Temp Drop 25 °F, (25-30 °F) Tube Spacing 6-9” o.c. Surf Temp 38 °F, (36-45 °F) Fluid Max 150 °F 200 Btu/sqft/hr

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Mechanical Components

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Snowmelt typical loop layout

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Architectural Considerations

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Installation Methods

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