A warning, Section 3 • understanding how your furnace works, Section – Bard Furnace 2100-287 User Manual

Page 5: 3 understanding how your furnace works, Warning, Important

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Never store anything combustible near or on

your furnace. These include brooms,

dustmops, vacuum cleaners, other cleaning

toots or items, plastic or plastic containers,

paper bags or other paper products. A fire
could occur resulting in damage, injury or
death.

B.3. ALTERATION OF FURNACE CONTROLS

A

WARNING

Do not alter any gas or electrical controls (gas

control, pilot or safety controls) in any manner.
Altering them could cause furnace to operate

unsafely resulting in damage, injury or death.

SECTION 3 • UNDERSTANDING HOW

YOUR FURNACE WORKS

3.1 BASIC FURNACE - HEATING CYCLE

This furnace is operated by an Integrated Furnace
Control (IFC) 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 IFC to proceed with ignition function.

There is a 36 second ignitor heat-up period, then the gas

valve opens introducing main burner gas to be ignited by the

hot surface ignitor. The flame sensor proves ignition and
carryover across all burners.

There is a 30 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 nm for 30
seconds, and the comfort air blower will continue to nm
approximately two minutes.

3.2 ACCESSORIES (OPTIONAL, FIELD

INSTALLED)

The furnace and IFC are designed to accommodate both

electronic air cleaner and humidifier. The electronic air
cleaner circuit is powered anytime the comfort air

blower runs on either heating or cooling speed. The
humidifier circuit is powered anytime the inducer motor is
operating.

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.

3.3 COOLING CYCLE OPERATION

If optional add-on air conditioning system is installed, the
comfort air blower runs on cooling speed will run
continuously during the call for cool; and will stop 60

seconds after the thermostat is satisfied.

* * 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 or air intake pipes
become 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.

3.4 MANUAL FAN (CONTINUOUS AIRFLOW)

OPERATION

If wall thermostat is set to MANUAL (ON) position to
operate comfort air blower continuously to provide air
circulation throughout the building, the blower will

operate on the heating speed rather than the cooling as is
typical with most systems. This permits the air to
circulate as desired but helps keep the operating noise

level down as well as conserving energy.

During a call for cooling, the blower automatically shifts up
to cooling speed, and remains there until 60 seconds
after thermostat is satisfied then drops back to heating

speed.

Manual
Page

2100-287

3

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