Raypak 1001 Operating And Installation Manual page 55

LOW WATER CUT OFF (OPTIONAL)
The low water cut off automatically shuts down the burner whenever
water level drops below the level of the sensing probe. A 3 second
time delay prevents premature lockout due to temporary conditions
such as power fluctuations or air pockets.
LOW WATER CUT OFF
HIGH AND LOW GAS PRESSURE SWITCHES - MANUAL RESET
The low gas pressure switch mounts upstream of the gas pressure regulator
to ensure that sufficient gas pressure is present for proper regulator performance.
The low gas pressure switch automatically shuts down the boiler if gas supply
drops below the factory setting of 6" W.C. for Natural gas, and 10" W.C. for
propane gas.
The high gas pressure switch (optional) mounts down-stream of the gas
pressure regulator. If the gas pressure regulator fails, the high gas pressure
switch automatically shuts down the burner.
GAS PRESSURE SWITCH
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