750-211 (revised 2009)
Promethean Boilers, Model 4WI Manual
1-7
1.5 — Hot Water Controls (All Fuels)
FIGURE 1-9. Safety Valve Piping and Safety Valves
1.5 — Hot Water Controls (All Fuels)
1.5.1 — Pressure and Temperature Gauges
1. Water Pressure Gauge: Indicates the boiler internal water pressure.
2. Water Temperature Gauge: Indicates the boiler water temperature.
1.5.2 — Controls
1. Modulating Temperature Control: Senses changing boiler water temperature and transmits the information
to the modulating motor to change the burner firing rate when the manual-automatic switch is set on “auto-
matic.”
2. High Limit Temperature Control: Breaks a circuit to stop burner operation on a rise of temperature at a
selected setting. It is adjusted to stop the burner at a preselected temperature above the operating control set-
ting. The high limit temperature control normally is equipped with a manual reset.
3. Operating Limit Temperature Control: Breaks a circuit to stop burner operation on a rise of boiler tempera-
ture at a selected setting. It is adjusted to stop or start the burner at a preselected operating temperature.
Only properly certified personnel such as the safety valve manufacturer’s certified representative can adjust or repair
the boiler safety valves. Failure to follow these instructions could result in serious injury or death.
!
Warning
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