How a Boiler Control Works

Figure 19 - Cold Start Operation (Low Limit ► OFF)

150	175
150	200
125	225
100	250
75	275

High Temperature Differential

(Adjustable 5° to 45°F)

Starts the burner when temperature drops to the HIGH LIMIT DIFFERENTIAL setting.

High Temperature Limit

(Adjustable 100° to 240°F)

Shuts burner off at HIGH LIMIT set point.

Example Shown:

High Limit = 200°

Differential = 20°

During a call for heat, the burner will be shut off at 200° and be turned back on at 180° (200°-20°). The circulator will continue to operate until the call for heat is satisﬁed.

50300

Figure 20 - Warm Start Operation (Low Limit ► ON) (To maintain domestic hot water temperature)

Low Temperature Differential

(Adjustable 10° to 45°F)

Shuts burner off when temperature rises to the LOW LIMIT DIFFERENTIAL setting.

High Temperature Differential

(Adjustable 5° to 45°F)

Starts the burner when temperature drops to the HIGH LIMIT DIFFERENTIAL setting.

Low Temperature Limit

(Adjustable 100° to 220°F)

Starts the burner at LOW LIMIT set point.

Example Shown:

Low Limit = 140°

Differential = 10°

During the OFF cycle with no call for heat, the burner is turned on at 140° to maintain the boiler water temperature and is shut off at 150° (140°+10°).

175

150 200

125225

100	250
75	275

High Temperature Limit

(Adjustable 100° to 240°F)

Shuts burner off at HIGH LIMIT set point.

Example Shown:

High Limit = 200°

Differential = 20°

During a call for heat, the burner will be shut off at 200° and be turned back on at 180° (200°-20°). The circulator will continue to operate until the call for heat is satisﬁed.

50300

Beckett 7600 manual How a Boiler Control Works