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6
Heating cable selection for roof & gutter de-icing
1. Calculate the heating cable length
required.
Total heating cable length:
Roof edge length (ft) × feet of heating cable
per foot of roof edge
+ Total gutter length (ft)
+ Total downspout length (ft) (+ 1 ft)
= Total heating cable length (ft)
Example: (standard roof)
Roof edge:
15 ft
Roof overhang:
1 ft
Roof gutter:
15 ft
Downspout:
15 ft
(at end of circuit)
Gardian heating cable required:
15 ft × 2
Roof edge:
(from Table 3)
Roof gutter:
15 ft
Downspout:
15 ft + 1 ft
61 ft
Gardian required:
W51-75P
Heating cable installation
Figure 5 Standard roof
1. Prepare for installation.
• Store the heating cable in a clean, dry place.
• Use only the following Tyco Thermal
Controls accessories to satisfy code and
agency requirements:
- H915 Hanger Bracket
- H913/H914 Roof Clips
• Make certain gutters and downspouts are
free of leaves and other debris.
• Carefully plan the routing of the heating cable
for roof and gutter de-icing.
2. Position and attach the heating cable on roofs.
• Loop the heating cable on the overhang
area of the roof. This is the part that
extends past the building wall. Extend the
bottom of each heating cable loop over the
roof edge and, using a UV-resistant cable
tie, connect the bottom of each loop to the
cable running in the gutter to ensure a
drainage channel off the roof and into the
gutter and downspout. The cable running
in the gutter should remain against the
bottom of the gutter as shown in Figures 5
and 6.
Table 3 Typical spacing and layout measurements
Eave overhang (in)
None*
12
24
36
* Gutter required
• For standard roofs, add 1 foot of heating cable for each foot of gutter.
• Add 1 foot of heating cable per foot of downspout. If downspout is in the middle of the run,
loop the Gardian down and back up. Double the length of the downspout for determining the
length of Gardian to install.
• For valleys, run the heating cable two thirds of the way up and down the valley .
UV-resistant cable tie
Table 4 Tracing heights for different roof styles
Roof
overhang (in)
None*
12
24
36
Eave
overhang (in)
None*
12
24
36
None*
12
24
36
* Gutter required
** No additional heating cable is required for gutters when tracing standing seam metal roofs
Length of cable per foot of roof edge (feet)
Standard roof
2
2
3
4
Figure 6 Standing seam metal roof
Shake and Shingle Roof
Tracing
Tracing
width (in)
heights (in)
2
18
2
18
2
30
2
42
Standing Seam Metal Roof**
Standing Seam
Tracing
Spacing (in)
heights (in)
18
18
18
24
18
36
18
48
24
18
24
24
24
36
24
48
Standing seam metal roof:
18" seam
24" seam
2.5
2
2.8
2.4
3.6
2.9
4.3
3.6
UV-resistant cable tie
Feet of Gardian per foot of
roof edge
not including gutter
2
2
3
4
Feet of Gardian per foot of
roof edge
2.5
2.8
3.6
4.3
2.0
2.4
2.9
3.6
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