508151-01
Issue 2104
Page 23 of 72
Flame Rollout Switches
Flame rollout switch is a high temperature limit located on
top of the burner box, one on each side.- See Figure 13.
The limit is a N.C. SPST manual-reset limit. When S47
senses rollout, the circuit breaks and the ignition control
immediately stops ignition and closes the gas valve.
Rollout can be caused by a blocked heat exchanger, flue
or lack of combustion air. The switch is factory set to trip
(open) at 210°F and cannot be adjusted. The switch can
be manually reset. To manually reset a tripped switch,
push the reset button located on the control.
Burners
All units use inshot burners. Burners are factory set and
require no adjustment. Always operate the unit with the
burner box front panel in place. Each burner uses an orifice
that is precisely matched to the burner input. Burners can
be removed as a one piece assembly for service. If burner
assembly has been removed, it is critical to align center
of each burner to the center of the clamshell when re-
installing. See more detail in Maintenance
.
Gas Valve
The valve (Figure 47) is internally redundant to assure
safety shut-off. If the gas valve must be replaced, the same
type valve must be used.
24VAC terminals and gas control knob are located on the
valve. A wire harness connects the terminals from the gas
valve to the electronic ignition control. 24V applied to the
terminals energizes the valve.
Inlet and outlet pressure taps are located on the valve. A
regulator adjustment screw is located on the valve.
LPG change over kits are available from Allied. Kits include
burner orifices and a gas valve.
Intake Air Top Cap
Sensor
Rollout Switch
Rollout Switch
Burner Assembly
Ignitor
Manifold And Gas Orifices
Two-Stage Gas Valve
Burner Box Cover
Figure 13. Heating Components