Bard 2100-066 Rev. A User Manual

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Refrigeration, Heating & Air Conditioning

Common Furnace Components and

Blower Maintenance Procedures

Bard Manufacturing Company

Bryan, Ohio 43506

Since 1914..Moving ahead, just as planned.

Manual No.: 2100-066 Rev, A

Date: 10/18/95

©Copyright 1995

Contents

 

Cabinet.................................................................................

1

Temperature Treatment Section........................................

1

Heat Sections.......................................................................

1

Cooling Section....................................................................

3

Biower...................................................................................

3

Beit Drive Biower.................................................................

3

Direct Drive Blower..............................................................

3

Filter.......................................................................................

3

Thermostat............................................................................

3

Electrical System Components...........................................

4

Furnace Circuits...................................................................

4

Blower Motors......................................................................

4

Fan Control Switch..............................................................

4

Downflow and Horizontal Units..........................................

5

Limit Control.........................................................................

6

Upper Limit Control.............................................................

6

Additive Cooling Relay........................................................

7

24 Volt or Low Voltage Control Circuit..............................

7

Transformer..........................................................................

7

Thermostat............................................................................

7

Basic Maintenance Procedures..........................................

7

Maintenance Check Sheet..................................................

7

Maintenance Checksheet....................................................

8

Pre-Service Check...............................................................

9

Thermostat............................................................................

9

Blower Compartment Check.............................................

10

Nondisposable Slab (Polyurethane)................................

10

Disposable Slab (Fiberglass/Cardboard)........................

10

Direct Drive Blower............................................................

10

Post-Service Checks.........................................................

12

Heat Section Checks.........................................................

12

Cabinet

Generally speaking, all heating and cooling components (except the thennostat) are housed in sheet steel cabinets. The cabinet helps protect the components and adds to the attractiveness of the units.

The heating unit or furnace cabinet is normally located indoors. It has connection provisions for attaching the cooling coil, supply air plenum and return air plenum. The cabinet also contains openings or knockouts for electrical service and required plumbing.

Designed into the cabinet are removable access doors to allow for servicing the unit. The front door to oil and gas furnaces is slotted to allow combustion air to enter (this is not necessary on electric furnaces, since no fuel is burned).

Since the cooling system’s outdoor unit is exposed to the weather elements and in the public eye, it is especially important the cabinet is durable, weather resistant and attractive in appearance. Like the furnace cabinet, the outdoor cooling unit cabinet has service access doors and provisions for electrical and mechanical (i.e. refrigerant line) connections.

Temperature Treatment Section

The temperature treatment section of a heating or cooling unit is that portion of the unit which produces the heating or cooling. (All types of heating units and cooling systems are discussed in greater detail in the sections that follow.)

Heat Sections

Most residential furnaces use either natural or liquefied propane (LP) gas, oil or electricity as their source of heat.

The heat section of an electric furnace consists of one or more electric heating elements. The element is much like that in an electric toaster, only bigger. When the thermostat demands heat, an electrical resistance to the flow of electricity in the element produces heat. The heated air is moved by the furnace blower through the ducts and distributed to points all over the home.

The heat section of a gas (either natural or propane) furnace consists of a steel heat exchanger and gas burners. The burners fit in a cavity at the bottom of the heat exchanger.

Gas is fed into the burners and ignited by a pilot flame on a call for heat from the thermostat. The burning gas warms the heat exchanger and the blower distributes the heat throughout the house.

The oil heat section is made up of a firebrick pot and steel heat exchanger. When the thermostat calls for heat, oil is pumped through a nozzle and ignited by a spark from a set of high voltage electrodes. A ball of fire is produced in the firebrick pot, which heats the steel heat exchanger. The blower then moves this heated air to the various distribution points.

Bard Total Electric Features

Built-In Cooling Coil Compartment—Slide- in type for easier conversion to summer cooling, Accomodates 1-1/2, 2, 2-1/2, and 3 ion

cooling coils.

Controls—On demand from the wall thermostat, the heating elements are energized by electrical contactors. The 15 thru 30K.W versions have the blower motor interlocked with each stage for safety. Easily two staged.

Limit Switch—Thermal snap disc in each heating element shuts oif power automatically if system air temperature becomes excessive

Built-In Transformer—Provides power supply for heating and optional cooling controls

Blower Relay—Provides automatic blower speed change-over to meet heating and cooling air delivery requirements.

Branch Circuit Fusing—Factory installed in models rated over 48 amps.

Heating Elements—Nickel-chrome wire with individual fusible links for long life. Entire assembly slides out for easy maintenance.

Motor—Multi-speed for both heating and cooling.

Blower—Heated air is quietly circulated by large volume centrifugal blower that is matched to the electrical heating system for efficiency. Slides out for easy maintenance.

Fillers—Twin permanent type slide out from front for easy cleaning on all models except Models EFC5 andEFClO.

Typical Gas Furnace

Sled Cabinet is accoustically and ihennaUy insulated for quieter operation and minimum heat loss.

Filter is extra large for better system air cleaning efficiency.

Heat Exchanger efficiently extracts all usable — heat for greater fuel economy.

Safety Pilot provides 100% automatic shut-o£f for safely.

Mono“.Jet® Burner provides ease in adjustment and has uniform flame distribution for maximum efficiency.

Powerful Blower Motor is resilient mounted for quieter operation.

Model G152

All components are easily accessible for service and inspection.

Typical Oil Furnace

Bard Cooling Coils with plenum and system matched components are optional for converting to summer air conditionirrg.

Electrostatic Air Cleaner traps up to 95% of air-bome dust, bacteria-size particles, smoke, odors and 99% pollen. This optional accessory may be installed with furnace or added later.

Fan and Limit Control with helcx element automatically controls blower and burner operation.

Blower is capaci^ matched to heating components and quietly circulates air throughout system.

steel Cabinet is accoustically and ihermaOy insulated for quieter operation and minimum heat loss.

Fan and Limit Control with helex element automatically controls blower and burner operation.

Heat Exchanger provides more heating surface for efficiency.

Motor has resilient base mounting for both heating or cooling applications.

Blower is centrifugal type, dynamically balanced and mounted on rubber grommets for quieter operation.

Burner is designed for super-quiet efficiency.

Typical Installations

Cooling Section

This cooling section in a typical split-system application is the indoor evaporator coil. This coil is located in the supply plenum of the furnace. Stated simply, cool refrigerant is pumped through the evaporator coil by the cooling unit. The refrigerant in the evaporator coil removes heat from the air, and the furnace blower distributes this cool air to the conditioned spaces.

Blower

The device which moves the treated air to points throughout the home is called the blower, The blower consists of a wheel with air scoops sometimes called a scroll and a motor to drive the wheel. There are two types of blowers; a belt drive and a direct drive.

Illustrated here are typical gas-fired and oil-burning counterllow furnaces.

Belt Drive Blower

A belt runs from a pulley mounted on the motor to a pulley mounted on the blower wheel, All moving parts are anchored on a rigid U-ffame, which in turn is fastened on resilient mountings to the furnace. The design of this frame insures easy adjustment and alignment of pulleys and belts for optimum performance. Varying amounts of air can be moved by a belt drive blower, depending upon the motor pulley size adjustment (see diagram). The pulley can be made larger by screwing one side of the pulley inward toward the other side; this causes the blower wheel to rotate faster. Screwing one side outward from the other side reduces the pulley's effective circumference, which in turn reduces the speed of the blower wheel. If volumes of air are desired, which caimot be obtained by motor pulley adjustment, the motor or blower pulleys themselves can be changed,

NOTE: A larger pulley might also necessitate a larger motor.

Direct Drive Blower

The direct drive blower motor is mounted inside the blower and is directly linked to the blower wheel. Air volume changes are made by electrically varying the speed of the motor. The speed in direct drive blowers is changed depending upon which of several wire leads (speed taps) coming from the motor are used. Usually two to five speeds can be obtained by wiring the hot wire to the desired

speed tap lead and the neutral wire to the common motor lead. The unused hot wire leads must be taped separately to prevent coming in contact with an electrical ground. The rotating motor produces a back voltage (emO of approximately 200 vac through electromagnetic induction.

A WARNING

Use caution when handling these leads with 200 vac electrical potential. If not taped, they could cause arcing to ground, shorts or serious electrical shocks.

Filter

A filter is the device in a forced air heating or cooling unit which mechanically screens out dust, dirt, lint and other impurities from the Systran's airstream.

The filter is usually located just upstream from the blower, in the return air side of the system. A fiberglass media commonly acts as the screen, cleaning the air before it is recirculated throughout the system by the blower.

A dirty filter greatly reduces the system's airflow, which greatly reduces the operating efficiency of the heating or cooling unit. For this reason, The homeowner should be instructed to check the filter monthly and clean or replace it if necessary. (Never reuse a dirty filter by turning it bottomside up; this will result in the collected dirt being dumped back into the airstream.)

Two types of filters are the disposable and the permanent. Most slab filters are disposable, consisting of rectangular fiberglass screen in a cardboard frame. These come in a variety of sizes to fit completely across the airstream. Arrows marked on the frame indicate correct placement with respect to system airflow. When the filter becomes dirty, it should simply be removed and a new one put in its place. A nondisposable slab filter uses a polyurethane media encased in a metal frame. When this filter becomes dirty, the media may be cleaned (washed or vacuumed) and reused.

Thermostat

The thermostat is a heat sensitive switch that serves as the automatic control center for heating and cooling system operation. Since the thermostat was discussed in detail in a previous manual, its story will not be repeated here. The student should review the manual on thermostats if necessary.

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