Rheem Raypak R207A Installation And Operation Manual page 31

Flame Roll-Out Safety Switch
Heaters are equipped with a thermal cutoff device to
prevent flame roll-out in the event the heat exchanger
becomes blocked. It is a "manual reset" type roll-out
switch that must be reset by a service technician after any
over-temperature conditions have been fixed. Excessive
restriction in the heat exchanger flue passage may cause
the switch to disable the heater.
Figure 53. Flame Roll-out Switch – Manual Reset
High Limits
The heater is equipped with two high limits.
On polymer headers both are automatic and are located in
the inlet/outlet header. Both are set at 135°F (57°C).
On ASME brass header both are located on the inlet/outlet
headers. HL1 is manual reset and set to open at 160°F
(71°C). HL2 is automatic and set to open at 135°F (57°C).
NOTE: An erratic high limit is often characteristic of
an internal heat exchanger problem, e.g. scale build-up,
defective bypass. Refer to "TROUBLESHOOTING" on
page 37.
AUTO RESET
Figure 54. High Limit Switches
High Limit Removal
1. Shut off main electrical power switch to heater.
2. Remove inlet/outlet sheet metal access panel.
3. Remove defective high limit and replace with the
correct, new high limit.
4. Replace access panel.
MANUAL RESET
(ASME ONLY)
F10669-1
Pilot Safety
The heater employs a pilot safety which closes the main
gas valve within 8/10ths of a second whenever the pilot
flame is interrupted. The pilot flame is automatically lit
when the device is powered. The heater performs its own
safety check and opens the main valve only after the pilot
is proven to be lit.
Burner Tray Removal
1. Shut off main electrical power switch to heater.
2. Shut off gas upstream of heater.
3. Remove front door.
4. Disconnect gas line from gas valve.
5. Remove (2) screws that mount burner tray to the
base of the unit, (2) screws that mount the blower
box to the burner tray, and (1) screw that secures the
anti-rotation bracket to the heater.
6. Disconnect wires that terminate at gas valve.
7. Unscrew (4) screws that secure the control box.
8. Disconnect pilot wire from the pilot assembly.
9. Disconnect wire connector from the combustion
blower.
10. Carefully slide out the burner tray assembly.
11. Reverse above procedure to reinstall.
Figure 55. Burner Tray Assembly
Gas Valve Removal
1. Shut off gas supply to the heater. Remove gas piping
to gas valve inlet.
2. Remove burner tray, following above procedure.
3. Disconnect, pilot tubing from gas valve.
4. Remove (2) screws that mount anti-rotation bracket
to the burner tray.
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