Raypak 206A Installation And Operation Manual page 33

A CAUTION: Do not operate the heater without the
function of a properly adjusted water pressure switch
or flow switch.
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. This is a "single-use" type fusible link
or thermal fuse, that must be replaced when disabled
by an over-temperature condition, caused by excessive
restriction in the heat exchanger flue passage.
Figure 58. Flame Roll-Out Safety Switch
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
header. 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 40.
AUTO RESET
Figure 59. 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.
F10668
MANUAL RESET
(ASME ONLY)
F10669-1
Pilot Safety - Millivolt Models
Heaters equipped with the standing pilot (millivolt system)
employs a pilot which act as a safety device to shut down
the flow of gas to the main burners and the pilot burner in
case the pilot flame is extinguished. The pilot burner must
be manually re-lighted to place the heater in operation
again. Refer to the lighting instructions provided on the
heater label.
Pilot Safety - Digital Models
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 unit,
and (2) screws that secure gas valve to jacket.
6. Disconnect wires that terminate at gas valve.
7. Disconnect hi-tension wire from PC board.
8. Carefully slide out burner tray assembly.
9. Reverse above procedure to reinstall.
BURNER
PILOT
BURNER
HOLD-DOWN
BRACKET
Figure 60. Burner Tray Assembly
Gas Valve Removal
1. Shut off gas supply to the heater. Remove gas piping
to gas valve inlet.
2. Disconnect wires, pilot tubing and bleed line, if
required.
3. Remove burner tray from heater.
GAS VALVE
GAS
ORIFICE
33