SlabHeat Installation Manual

5
Phase 1: Designing the System
SlabHeat cable should be installed in all interior floor areas that are to be warmed. It cannot be used for exterior applications, snow
melting, or in ceilings. In many applications, it can be used to heat the room as well, but an accurate heat-loss calculation must be
made to determine if enough heat will be provided to match the heat loss of the room.
STEP 1.1 Make a sketch of the room. Measure the total square footage of floor area to be warmed (measurements should be made
all the way to the edge of walls, cabinets, tub, etc., for now). Keep in mind the following:
• Heat will not radiate beyond about 3"- 4" on either side of the heating cable, therefore consistent coverage is important.
• Do not install the cables underneath cabinets or fixtures or inside a wall. Excessive heat will build up and cause damage.
• Do not run the heating cables into small closets or other confined areas where excessive heat will build up.
• Do install heating cable within about 1-1/2" to 2" from a counter or vanity in the kick-space to ensure warmth in this area.
• Do not install the heating cables closer than 6" from toilet rings to avoid possible melting of wax rings.
• Do not cross expansion joints in a slab unless proper technique and protection steps are followed. (see Step 3.10)
• Do not place the heating cable any closer than 4 inches from other items such as underground cable or piping to avoid
overheating them.
• Cable must be laid such that the surface will not have other obstructions placed on top, capturing heat or allowing potential
damage from mounting brackets, bolts, or similar (pedestals, support columns, walls, or similar).
• In open areas, like sun rooms or dining rooms, consider installing the heating cables 4" to 6" away from the perimeter of the room
since people rarely stand this close to walls. However, if the cable is installed in a slab where an exterior wall will be built, remember
to keep the cable 8" to 12" away from the edge of the slab.
• The heating cable and factory splices must be completely embedded in the concrete. Only the power lead may exit the slab. It will
be pulled through UL Listed conduit to a UL Listed junction box or the control box.
• For a new concrete slab, when a run of cable exceeds 20 feet, an additional U-shaped loop should be added to help minimize
possible damage to the cable from thermal expansion.
STEP 1.2
Select the cable spacing. Below are typical spacings for various types of rooms. This spacing can vary depending on the insulation of
the floor and room, and the desired effect. Note: Never space cables closer than 4" apart; this will cause a very hot area and may
cause damage.
Typical uses:
• 4" spacing: Sun room floors, basement slabs, bathrooms, kitchens, living areas, and baths with exterior walls. (NOTE: Insulation
is always recommended due to high heat losses in these areas. Performance is never guaranteed due to construction and climate
differences in these applications.)
• 6" spacing: Hallways, entry ways, and large areas with low heat loss.
Expected floor temperature:
• Insulated concrete slab: With the cables installed on an insulated concrete slab, and thin-set mortar and tile on top, most floors
can be heated up to 15F (9C) warmer than they would otherwise be.
• Uninsulated concrete slabs: With the cables installed on an uninsulated concrete slab, and thin-set mortar and tile on top, most
floors can be heated up to 10-15F (6 to -9C) warmer than they would otherwise be.
Please consult a designer or the factory if questions remain about the surface temperature that can be expected from the cables
in any particular construction.
STEP 1.3 Multiply the square footage measured in Step 1.1 by 0.90 to allow for 4" to 6" spacing around the edges of the floor area.
Use this resulting square footage to select the appropriate cables from the tables on page 6.
Remember:
• Do not place over 15 amps at 120 VAC (1800 watts) or 15 amps (3600 watts) at 240 VAC through a control.
• Select either 120 VAC or 240 VAC depending on the power available. DO NOT mix voltages on the same system if more than one
cable is to be installed to cover an area.
• Load no more than 12 amps (1440 watts) on a 15-amp circuit breaker, or 16 amps (1920 watts) on a 20-amp circuit breaker.
• If you have an area that requires more than 15 amps of cables to be controlled by one thermostat, use SunStat Relay(s) to take the
additional amp load.
• See the Wiring Diagrams in Appendix 1 for help.
If the exact size of product calculated is not found in the selection tables on page 6, it may be necessary to adjust the warming
area(s) or select the next smaller size. Remember, the heating cable must never be cut shorter to fit, and must be completely
embedded in concrete in the floor. Failure to do so may result in damage to the product. Be careful not to select a product
that is too large.
STEP 1.4
If installing SlabHeat on top of an existing slab, select enough CableStrap™ to secure the cable to the floor. One box contains 25 ft. of
strap, enough to prepare about 50 sq. ft. of floor at 4-ft. spacing. Strap is usually spaced every 3 to 4 ft. across the floor.