Install Instructions

Designing a SunTouch UnderFloor System
SunTouch UnderFloor Installation Manual 3
In general, SunTouch UnderFloor
should be installed in all floor areas
where floor warming is desired. It can
be installed to either warm the floor
or to heat the space. If SunTouch is
being installed to heat the space, first
perform a heat loss calculation. Use
RadiantWorks
® or a similar program to
calculate the heat loss of the room(s).
SunTouch can be expected to provide
approximately 34 BTU/hr/sq.ft. of mat.
This assumes the mats are installed
per this manual, including the use of
proper insulation techniques. Make
sure insulation is installed as shown
on page 10. There must be a “dead air
space” for UnderFloor mats to be effec-
tive. This output also assumes a floor
covering other than carpet and pad.
The output will be greatly diminished
with a carpet floor covering and/or the
lack of proper insulation.
Determine how much Mat is
Needed for the Installaton
To determine how much mat is
needed, take one of two approaches:
1. For a rough estimate, multiply
the wall-to-wall area by 75%–80%.
Convert this to linear feet of mat and
select from the lengths of mat shown
in the table on page 6.
2. For an accurate measurement,
look under the subfloor to see where
mats can be stapled. Looking carefully
at each joist bay, measure the length of
open area in that bay that can receive
a mat, and select the mat from the
table on page 6 that fits the space.
Remember that these mats cannot be
cut shorter to fit, nor modified in any
way to fit multiple joist bays. Do not
include in these measurements areas
that contain items that would obstruct
installation of the mat (return air
ducts, supply ducts, light fixtures, etc.).
Where mats are not installed, the floor
above will not get very warm.
Wiring Multiple Mats Together
Each mat is designed to be installed
in only one joist bay. The mats cannot
be cut shorter to fit a shorter joist bay
or modified in any way to fill multiple
joist bays. However, more than one
mat may be installed in a joist bay
where there are barriers such as cross
bracing. A typical installation is shown
below.
Since several mats will be required
to warm the floor area, the mats must
be wired together in parallel (not in
series) at a junction box below the
floor, then electrical wire fed from
there up to the floor-sensing control
box. Select mats for the easiest wiring
possible. If all the power leads end up
at one end of the room, it will be much
easier to wire them together in the
junction box. The junction box must
be accessible after all finishing work
is completed. Be sure to position the
mats so that this is possible.
Mat Voltage Requirements
Select either 120-VAC mats or
240-VAC mats (see table on page 6).
Do not mix 120-VAC mats and con-
trols with 240-VAC mats and controls.
Observe these general voltage guide-
lines:
1. For areas totaling up to about
190 sq. ft. (about 15 amps), use
120-VAC mats with a SunStat™ control.
2. For areas exceeding about 190
sq. ft. and up to about 350 sq. ft., use
240-VAC mats with a SunStat control to
have mats totaling 15 amps or less.
3. Use 240-VAC mats and a
SunStat/SunStat Relay control system
(see wiring diagrams in Part 6) for mats
totaling more than 15 amps at 240
VAC.
Regardless of the voltage require-
ments in a particular installation, make
sure the circuit breaker can handle the
load. Follow all electrical codes for
determining the size of the breaker.
Floor-sensing Controls
To control the SunTouch UnderFloor
system, install either a programmable
or non-programmable, floor-sensing
SunTouch SunStat or SunStat Relay
system. The sensor should be installed
per instructions in Part 2 (page 7).
Please reference the SunTouch cata-
log, or contact a SunTouch distributor
for more information.
Floor joist
Cross bridging or blocks
Insulated around outside of area
Insulated underneath mat
Areas with ductwork or piping
may not allow mat.
Insulated at ends
UnderFloor mats
Install mats 2” below subfloor
UnderFloor mat
(with 2” air gap
above the mat)