How to install indoor floor heating cable
Created Oct 14 2005 by Stan, Mru
There are 2
basic types of floor heating cables:
Some cables are
'more powerful', some are 'weaker'.
The designation
here is by the Watts per running unit of
length of the cable.
E.g.
VCD10/550
cable is 550W/240V cable powered on one end and 'weak' 10Watts/run. meter
or 3.1 Watts/run. ft.
VC20/2920
is 2920W/240V cable powered at both ends and 20W/run. m. or 6.25W/run.
ft.
All of
the designations of Watts per running unit
are:
(Mostly
indoors)
10 Watts/run. meter
or 3.1 Watts/run. ft. (both VC & VCD)
15 Watts/run. meter
or 4.7 Watts/run. ft. (VC only)
17 Watts/run. meter
or 5.3 Watts/run. ft. (VCD only)
(Mosty
outdoors)
20 Watts/run. meter
or 6.25 Watts/run. ft (VC only)
25 Watts/run.
meter or 7.8 Watts/run. ft. (VCD only)
Which one to
use?
VCD
cables are
thicker (as thick as your cable TV wire) because they have 2 heating cores.
VC cables are
thinner as they have only one heating core. About half the size of VCD
thickness.
The thicker
the mud job (self leveler, mortar or thickset) the more powerful cable
can be used.
E.g.
VC10 or VCD10 -
1/2" or thicker of the mud job.
VC15 or
VCD17 - 3/4" or thicker of the mud job.
Tools needed:
1. Cable tacker
2. Measuring tape
3. Calculator
4. Electric meter
Heating cable
cannot be cut to size. It is what it
is and over 180 models are available based on length and Wattage.
Heating
cables cannot cross or be closer than 2"!
1.
Measure the square footage of the room. DON'T ESTIMATE, measure exactly what the
square footage is.
WALKING AREA
ONLY. Not under permanent fixtures, shower stalls, cabinets etc.
Tip: when
measuring the floor leave some 5-6" off the wall not covered. You could use
this area as a "buffer zone" to install the cable in later in case you will have
some cable "leftover" at the end. Remember, it cannot be cut and everything must
be used up.
Plan for
anywhere between 9-15 Watts/s.f.
E.g. 193 s.f. ?
VCD10/1900
a 1900 Watts 240V cable is good for 1/2"-3/4" floor mud job.
This particular
cable is 617 ft. long.
For thicker floor
VC15/1900 or VCD17/1920 are good.
Any of the above
cables will produce 10 Watts/s.f.
2.
After receiving the cable check the resistance or continuity of the heating
element with the meter.
3.
Plan for the spot for flex conduit (included) for the thermostat floor
temperature sensor installation. 2-3" away from actual heating element is
good.
4. How
to calculate the distance between each run of the cable?
Convert 193 s.f.
into square inches.
E.g. 193 s.f. x
12 x 12 = 27765 sq. inches.
Convert the
length of the cable
E.g. 617 ft. =
7404 in. long.
Divide 27765/7404
= 3.75 in. or 3 3/4" apart
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