Bard WG-Series Understanding How Your Furnace Works, Alteration Of Furnace Controls

2.3 ALTERATION OF FURNACE CONTROLS

WARNING

Do not alter any gas or electrical controls (gas control or safety controls) in any manner. Altering them could cause furnace to operate unsafely resulting in damage, injury or death.

The ignition system consists of a direct spark igniter (DSI) and remote sensor. When the thermostat calls for heat the DSI sparks to light main burner gas.

Once ignited the remote sensor confirms flame carryover to all burners.

There is a 60 second delay after main burner is on until the comfort air blower starts on heating speed. After the thermostat is satisfied, the burners will go off as gas valve closes. The inducer will continue to run for 30 seconds, and the comfort air blower will continue to run for 2-1/2 minutes.

SECTION 3 • UNDERSTANDING HOW YOUR FURNACE WORKS

Your installer should have given you a detailed explanation of how the furnace operates. Shown below are the basic operation characteristics and sequence of operation. If you have any questions consult your installer and/or service agency.

* * IMPORTANT * *

There are many types of thermostats compatible with this furnace. Make sure you understand the specific type installed. Ask installer for detailed explanation, and retain thermostat instruction manual for reference.

This furnace is equipped with a vent shut-off system which monitors the combustion air into the burners by means of a pressure sensing device. When the vent becomes blocked, this device turns off the gas valve circuit to prevent flue products from entering the structure. In the event that this occurs, shut off furnace and contact a qualified service agency.

3.1 BASIC OPERATION – HEATING CYCLE

This furnace is operated by an Integrated Furnace Control (IFC) and a gas control system which controls all functions of the furnace.

On a call for heat from the thermostat, the IFC first turns on the inducer motor. The pressure switch then closes signaling the ignition control to proceed with ignition function.

3.2 BASIC OPERATION – COOLING CYCLE

On a call for cool the compressor and condenser fan will start immediately, and the comfort air blower will start 7 seconds later on cooling speed. Note: Some models may be equipped with optional Low Ambient Control that will cycle the condenser fan motor to maintain proper refrigerant pressures under lower outdoor temperature conditions. When the thermostat is satisfied the compressor and condenser fan will stop and the comfort air blower will continue to operate for 60 seconds.

3.2.1COMPRESSOR CONTROL MODULE (CCM)

All models are equipped with a compressor control module. This control is an anti-short cycle/lockout timer with high and low pressure switch monitoring and alarm relay output.

Delay on Make Timer and Break Time Delay

•On initial power up, or any time the power is interrupted to the unit, the delay on make period begins. This delay will be 2 minutes plus 10% of the delay on break setting. This feature assures that pressures will be equalized for normal start up if there are brief power interruptions, and can accommodate staggered starts for dual unit installations as long as the off delay periods are set differently for the two units.

•During routine operation of the unit with no power interruptions the compressor will operate on demand with no delay as long as off delay time has been met.

•Adjustable 30 second to 5 minute delay on break timer assures that pressures can equalize if units are short cycled by the operating controls or personnel. Recommended settings would be 2 minutes for unit 1 and 3 minutes for Unit 2.

Manual 2100-366 Page 3