Lennox International Inc Gas-Fired Hot Water Boiler, GWB9-075IH-2 Controls and Accessories

CONTROLS AND ACCESSORIES

This section provides a brief description of the key controls and accessories found in this boiler.

See Figure 26, Page 41 for detailed sequence of operation. See the Repair Parts Manual for locations of all control components and accessories described.

Integrated Boiler Control (IBC)

Integrated Boiler Control (IBC) is a microprocessor based controller for high efficiency gas boiler that monitors

all safety controls and which controls operation of the combustion air blower, circulator pump, burner, and a combination direct spark igniter/flame sensor. This controller is not intended for use with a vent damper. Controller is mounted on control panel inside of boiler and contains a three character user interface display.

High Limit Control

High Limit Control determines maximum boiler water temperature and also provides means for protecting boiler and heating system from unsafe operating conditions which could damage boiler.

Limit control sensor is mounted in ¾” NPT control well on top of the front boiler section at hot water outlet.

Limit control is incorporated in IBC and is field adjustable between 80°F and 190°F.

Field setpoint adjustment for each installation depends on heating system requirements.

Limit Control automatically resets when boiler water temperature decreases (10-30°F adjustable differential).

Differential can be adjusted to provide flexibility for boiler operation. Larger the differential, longer run cycle of boiler.

Thermal Purge Operation

1.Thermal purge feature complies with 2012 DOE and NRCan requirements that boiler control must incorporate automatic means to adjust water temperature.

2.Intent of thermal purge is to insure usable residual heat in the boiler is circulated until it is sufficiently depleted from the system before the burner is allowed to fire. To that end, on call for heat, burner is held off while circulator runs until boiler temperature drops to thermal purge temperature limit or time delay is exceeded. Both of these parameters are adjustable.

3.When boiler temperature falls below thermal purge temperature limit or time delay expires, burner is allowed to fire.

In addition to thermal purge temperature and thermal purge time delay parameters, two other conditions release integrated boiler controller from thermal purge and allow burner to run in order to maintain comfort in the space.

•Boiler temperature has dropped 10°F from boiler water temperature measured at beginning of the call for heat.

•Boiler temperature is cooling at a rate greater than 5°F/minute while circulator is running.

4.For Installations using Indirect Hot Water Heater

Depending on the specific installation, thermal purge delay might or might not affect end user’s expectation for domestic hot water delivery. In event the customer has a concern that it takes too long for hot water, the situation may be resolved in three ways.

A.Add a Domestic Hot Water Module, ECR part Number 240009562 (Honeywell part number W8375s1008). This control senses when hot water is being drawn, and instructs the integrated boiler control to bypass the thermal purge operation until domestic how water draw ends. Thermal purge will then be re-enabled.

DHW module incorporates a temperature sensor installed at the indirect water heater’s hot water supply fitting ( Note - this sensor is in addition to, not in place of, the limit control on the hot water tank.) The Module is connected to the Enviracom terminals in the Integrated Boiler Control.

B.Thermal purge parameters may be adjusted (higher thermal purge temperature limit and/or shorter thermal purge time delay) to bring the burner on sooner.

C.Thermal purge function can be disabled.

Gas Control Valve

Electrically controlled Combination Gas Control Valve is designed to meet requirements for use with direct ignition systems found in this boiler. Valve is piped to gas/air mixer.

Direct Spark Igniter

Direct spark igniter utilizes a spark gap to initiate gas combustion in the burner. Igniter is mounted next to burner through gas/air mixer. The igniter also serves as means for proving main burner flame by flame rectification. In the event of a lack of flame signal on three (3) consecutive tri- als for ignition, IBC will lockout and display Error Code 62.

Draft Inducer Temperature Safety Switch

Draft Inducer Temperature Safety Switch is a disc thermostat (180 °F setpoint) located on induced draft fan outlet port. Switch protects inducer and vent pipe from potential high temperature condition for discharging flue gases. Condition would typically be result of higher high limit control setting or over firing. Temperature safety switch automatically resets when the vent temperature decreases. (15 °F switch differential).

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