Gas/Propane Basics
Wiring
DO NOT short gas valve terminals. This will damage
the wall thermostat and void the warranty.
1. Check the system for the proper transformer by
comparing the VA ratings of the transformer and
the system. The system rating is determined
by multiplying the voltage draw x the amp draw.
Normally 20VA transformers are sufficient for
heating only applications and 40VA for heating /
cooling applications. (Note: improper transformer
VA ratings will cause erratic system operation).
2. Locate the white wire terminal adaptor (jumper)
that is included with the 720-079 gas valve.
3. Connect the white wire terminal adaptor
to the “M”
and “P” terminals on the 720-079 gas
valve.
4. Determine which wire was connected to
the “main valve” terminal on the original
valve. Connect this wire to the remaining
terminal on the white wire terminal adaptor.
Direct Spark: Pilot Outlet
Figure 6 illustrates the wiring and instructions
for direct spark ignition either remote
or direct sense. The installation instructions
for the pilot outlet are:
First, install the pilot tubing plug packaged
in the 720-079 gas valve.
Wiring
DO NOT short gas valve terminals. This will
damage the wall thermostat and void the
warranty.
1. Check the system for the proper trans-
former by comparing the VA ratings of the
transformer and the system. The system rating
is determined by multiplying the voltage
draw x the amp draw. Normally, 20VA
transformers are sufficient for heating-only
applications and 40VA for heating/cooling
applications. (Note: improper transformer VA
rating will cause erratic system operation).
2. Locate the white wire terminal adaptor (jumper)
that is included with the 720-079 gas valve.
3. Connect the white wire terminal adaptor to the “M”
and “P” terminals on the 720-079 gas valve.
4. Determine which wire was connected to the “main
valve” terminal on the original valve. Connect this
wire to the remaining terminal on the white wire
terminal adaptor.
5. Connect the remaining wire from the
original gas
valve to the “C” terminal on the 720-079
gas valve.
Operating Instructions
The operating instructions are as follows:
1. Turn the wall thermostat to its lowest
setting. Remove burner access panel(s).
Selector arm must only be operated by
hand (see illustration in Figure 7). Do
not use pliers, wrenches or other tools
to operate the arm. The selector arm
cannot be moved into the Off position
without first depressing the lever in
the On position.
2. Move selector arm to the Off position.
3. WARNING: Wait at least five minutes
to allow any gas in the combustion
chamber to vent; if you then smell gas
in the appliance area or near the floor,
Figure 5
Typical Robertshaw Hot Surface Application
Figure 6
Typical Robertshaw Direct Spark Application
18 ICM/March/April 2021