RELAYS
COMPREESSOR CONTACTOR
contacts ,while others use 2-pole or 3-pole contacts.
compressor and
outdoor fan.
OPTIONAL
D
ELAYS AND KITS
before re-starting the compressor.
Defrost
PCB
START KITS(OPTIONAL)
This special relay uses the EMF generated by the compressor start windings to take a start capacitor out
of the circuit. The relay and its companion capacitor can start the compressor at low voltages and
against higher pressure, such as those caused by non-bleed port expansion valves.
compressor make a start kit unnecessary.
.
The coil uses 24 volts but the contacts carry line voltage .The heater contactor is a large relay,
which controls the compressor and the outdoor fan operation. Some contactor use single pole
Before specifying any air conditioning equipment, a survey of the structure and a heat gain calculation
The cooling load calculation determines the unit size. There are two capacities that enable the
must be made. A heat gain calculation involves identifying all surfaces and openings that gain heat from
the surrounding air and quantifying that heat gain. The heat calculation also calculates the extra
heaty load caused by sunlight and by humidity removal. These factors must be considered before
selection an air conditioning system to provide year round comfort. The Air Conditioning Contractors
cooling load.
6. APPLICATION
of America (ACCA) J Manual method of load calculation is one recognized procedure for determining the
Fig.5-2
Generally relays used in air conditioning use 24VAC coils. Contact voltage may be either low or line voltage.
Relays provide a method for control switching. Relays may switch either low(24VAC) or line voltage.
Single-pole contactors break only one side of the power feed to the compressor and outdoor fan. The other side
remains connected to the power source. The 2-pole or 3-pole contactor breaks power to all sides of the
CAUTION: WHEN THERE IS A SINGLE POLE CONTACTOR, ONE SIDE OF A 240 V.A.C.CIRCUIT
REMAINS HOT. THIS MEANS THAT THE WIRING IN THE HIGH VOLTAGE CIRCUIT MAY HAVE A
POTENTIAL OF 120V.A.C.TO GROUD. BEFORE SERVICING THE UNIT, ALWAYS TURN OFF
POWDER AT THE UNIT DISCONNECT SWITCH.
A Time-Delay in the compressor contactor lowcontrol circuit allows time for system pressure to equalize
This
d
elay uses solid state circuitry to measure the time since the power was interrupted and is set for
approximately 3 minutes. It is not field adjustable. This is a delay on break timer.
Start kit components should match the recommended ratings and functions of those provided by the
Start kits are not normally required with scroll compressors. The operating characteristics of the scroll
reciprocating compressor manufactorer. See Specifications start components.
Sensible heat is the heat energy
measured on the dry bulb thermometer.
equipment to provide comfort. The first is sensible capacity.
11
Central Air Conditi
oning
Model: Heat Pump,
HR13-D2
