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WIRING – CAPL-2

CAPACITY CONTROLLERS – CAPL-2

OVERVIEW

The Zonex Systems CAPL-2 is a combination staging and capacity control
device for use with gas/electric units and heat pumps that use standard
gas/electric thermostats. It can stage an economizer, two stages of cooling
and up to two compressors and two stages of heat. The CAPL-2 monitors
the leaving air temperature and stages the cooling or heating to maintain
the leaving air temperature within a fixed range. Controlling the staging
based on the leaving air temperature ensures the supply always matches
the load. This is essential with a zoning system since the load varies sub-
stantially as the number of zones calling varies.

Cool Mode

– When there is a cool call, if the leaving air is above the cool

cut-in temperature, the CAPL-2 turns on the next stage compressor after
a time delay. If the air gets too cold, it turns off the last stage compressor
after that compressor has run a minimum of four minutes. As long as
there is a cool call, when a compressor turns off it will stay off for a
minimum of four minutes if the jumper is on ECON and when a compres-
sor turns on it will run a minimum of four minutes. This prevents
short cycling and ensures sufficient compressor oil return. When the
cool call is removed, all compressors are immediately turned off.

Heat Mode (Gas/Electric)

– If the leaving air is below the heat cut-

in temperature, it turns on the next heat stage after a time delay. If the air
gets too warm, it turns off the last heat stage after a time delay. When the
heat call is removed, all heat stages turn off immediately.

Heat Mode (Heat Pump)

– When there is a heat call, if the leaving air

is below the heat cut in temperature, the CAPL-2 turns on the next stage
heat after a time delay. If the air gets too warm, it turns off the last stage
heat after that stage has run a minimum of four minutes. As long as there
is a heat call, when a heat stage turns off, it will stay off for a minimum of
four minutes and when a heat stage turns on it will run a minimum of four
minutes. This prevents short cycling and ensures sufficient compressor
oil return. When the heat call is removed, all compressors are immediately
turned off.

SEQUENCE OF OPERATION

The following sequence of operation assumes the cool cut-out setpoint is
48 degrees Fahrenheit and the heat setpoint is 150 degrees for
gas/electric units and 118 degrees for heat pump units. For any other
cut-out settings, add or subtract the difference to the values stated.
Example: If your actual cool cut-out is 50 degrees, add 2 degrees to each
temperature value stated under the Cooling Call section. All temperatures
are in degrees Fahrenheit.

COOLING CALL

(cool setpoint 48): As long as there is a cooling call

(YIN energized), the following will occur.

ECONOMIZER:

• As long as there is a cooling call the economizer, if available, is enabled

and outside air is supplied based on enthalpy. The Economizer
selection jumper must be on ECON if there is an economizer. If no
economizer, place jumper on ECOFF.

COMPRESSOR STAGING ON

• If

the

leaving air is 58 degrees or greater

and no compressors are

running, compressor one will turn on within six minutes. If compressor
one is running, compressor two will turn on within eight minutes.

COMPRESSOR STAGING OFF

• If the

leaving air is between 48 and 52 degrees

and

compressor two is running, compressor two will shut off after
running a minimum of four minutes. Compressor one will shut off
after it has been on a minimum of four minutes and compressor two
has been off a minimum of six minutes.

• If the

leaving air is 48 degrees or less,

then all compressors will turn

off after the last compressor running has run for at least four minutes.

NO STAGING:

• If the

leaving air is equal to or greater than 52 and less than

58 degrees,

then no compressor staging will occur.

HEATING CALL (Gas/Electric)

(The factory heat setpoint is 150.

Heat setpoint may be field modified to compensate for local temperatures