Lochinvar 150 Outdoor Air Reset Option, High-FireOffset, Shutdown, Outdoor Air Max O.A. Max

Set Point

The Set Point knob specifies the target water temperature in degrees, Fahrenheit. After the water temperature reaches the set point, the temperature control shuts off the burners.

Differential

The Differential specifies the number of degrees below the set point that the control will allow the water temperature to drop before it brings the appliance back on again.

High-Fire Offset

The temperature control operates a two-stage firing system. The two stages are High-Fire and Low-Fire. High-Fire operates all burners while Low-Fire operates approximately one-half of the burners.

The High-Fire knob specifies the number of degrees below set point that the High-Fire stage shuts down. At that point, the appliance will continue to operate at the Low-Fire stage until the set point is reached.

The High-Fire offset knob has settings between 0°F and 20°F. If set at 0°F, the High-Fire offset is disabled and the appliance will operate at the High-Fire stage until the set point is reached and the temperature control shuts the appliance off.

No matter what the High-Fire offset knob is set to, the appliance will light at Low Fire and operate for approximately 10 to 120 seconds before the High-Fire stage actuates.

OUTDOOR AIR RESET OPTION

Outdoor Air Reset Option

For boilers ordered with the Outdoor Air Reset option, there is an additional control (FIG. 6). There are three setting knobs for Shutdown, Outdoor Air Max., and Ratio. There is also a switch to turn the outdoor air shutdown feature On or Off. An O.A. Sensor is also included.

(c)2002 L.C.			55				CN1						CN2	CN3
CN7		50		60											OJ1
CN8	D4	45		65		O.A. SENSOR								CN4	C10
							ON ENABLE
			VR3				SW1
	W1	40		70			DISABLE							CN5	OJ2
		SHUTDOWN				O.A. SHUTDOWN						R6 R4 C7
		50	55	60		0.80.9 1.01.11.2								CN6	C9
		45		65		0.7				1.3			W3	J4
			VR1			0.6		VR2		1.4				R8
		40		70			0.5		1.5
CN1												W1	W2
		O.A. MAX.					RATIO
	160														CN9
						9	10 11						10
			200
140					8			12				5		15
								13		R15	R16
				220	7
								14
120					6
					5		VR2	15			(F-)0		VR3	20
			240
	OFF			DIFFERENTIAL								HIGH-FIRE
	SETPOINT					TST2314						OFFSET

FIG. 6 Optional Outdoor Air Reset Control

Shutdown

The Shutdown knob specifies the outdoor air lockout temperature at which the control would prevent the appliance from operating.

Outdoor Air Max (O.A. Max)

The O.A. Max knob allows a reset up to the maximum outdoor air temperature specified by this knob setting. At any outdoor air temperature above the specified setting, the appliance will not reset but will continue to run at the set point temperature.

Ratio

The Ratio knob allows control over the reset ratio to be used during Outdoor Air Reset. The allowable ratios are as low as 0.5:1 or as high as 1.5:1.

Selecting the 0.5:1 ratio will increase the set point 0.5°F for every 1.0°F drop in outdoor air temperature up to the maximum set point temperature.

Selecting the 1.5:1 ratio will increase the set point 1.5°F for every 1.0°F drop in outdoor air temperature up to the maximum set point temperature.

See Figure 7 for an outdoor air reset chart example.

FIG. 7 Outdoor Air Control Example Chart

Outdoor Air Shutdown Enable/Disable Switch

The Outdoor Air Shutdown Enable/Disable switch turns the outdoor air shutdown feature On and Off. Disabling the Outdoor Air Shutdown feature allows the appliance to operate regardless of the outdoor air temperature. This is needed for indirect domestic hot water systems for example.

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