Installation, Operation and Maintenance Manual
Marvel Plus
7
Subject to change without notice.
120.5-IM (1018)
Humidification (Option)
If the system has the Humidification Option, humidification
will operate based on return air humidity� When the return air
humidity is less then the return air humidity set point minus
the Band set point, humidification is enabled. Humidification
is then sequenced ON and OFF based on the return
air humidity requirement or humidification demand. The
percentage of humidification demand is determined by how
far the return air humidity is below the return air humidity set
point�
Dehumidification (Option)
If the system has the Dehumidification Option,
dehumidification is sequenced based on return air humidity.
When the return air humidity is greater than the return air
humidity set point plus the Band set point, dehumidification
mode is enabled. Dehumidification is then sequenced /
staged ON and OFF by cycling compressors based on the
dehumidification requirement or dehumidification demand.
The percentage of dehumidification demand is determined
by how far the return air humidity is above the return air
humidity set point�
Reheat Mode (Option)
If the system has the Dehumidification Option and the
optional factory provided heaters or hot gas reheat coil and
valve, the heaters/hot gas reheat coils are available for the
Reheat Mode Option� The heater(s) will be activated for the
Reheat Function during the Dehumidification Mode. Reheat
function is based on both Return Air Temperature and
Supply Air Temperature and their respective set point� If the
return air temperature falls below the return air temperature
set point or the supply air temperature falls below the supply
air temperature set point, the reheat is brought on and
applied based on whichever demand for heating is greater�
The reheat demand is based on how far the temperature is
from the set point and whichever demand is greater (reheat
demand based on supply air temperature or reheat demand
based on return air temperature)� For systems with multiple
stages of heater, the quantity of heaters for Reheat Mode
is determined by the heating demand based on return air
temperature�
Air Side Economizer (Option)
If the system has the Airside Economizer Option, the system
will utilize the airside economizer when the outdoor air
enthalpy is less than return air enthalpy and the outdoor
air temperature is less than the outdoor air temperature set
point minus the Band set point� Once the outdoor air enthalpy
is verified, the Marvel Plus controller sends a modulating
signal (0-10vdc) to the field interlock terminal strip as shown
on the electrical diagram provided with the unit� The signal
provided will maintain the supply air temperature as close
to the supply air temperature set point as possible until the
return air temperature (cooling requirement) is satisfied.
INFORMATION
The minimum position damper setting may in some
instances affect system operation if too much outdoor air is
continuously introduced to the space being controlled�
Air Side Economizer - Compressor Assist
Mode
Mechanical Cooling Assist is a function available for
applications where the outdoor air temperature cannot meet
the cooling demand requirements� The Mechanical Cooling
Assist function has an adjustable time delay (minutes) before
mechanical cooling compressor stages are energized to
assist with the Airside Economizer option�
Water Side Economizer (Option)
The Water Side Economizer Option provides an economical
method of cooling when a free-cool coil can be utilized� If the
system has a free-cool coil and a cooling tower available,
the system will use free cooling when the water temperature
is below the free-cool temperature setting� If the water
temperature is above the free-cool setting, the system will
use mechanical cooling� If the water temperature is below
the free-cool setting, the water valve for free-cool mode will
modulate open to satisfy the cooling requirement�
Water Side Economizer - Compressor Assist
Mode
Mechanical Cooling Assist is a function available for
applications where the waterside economizer function cannot
meet the cooling demand requirements� The Mechanical
Cooling Assist function has an adjustable time delay
(minutes) before mechanical cooling compressor stages are
energized to assist with the Water Side Economizer option�
