As the damper opens one deck it closes the other and vice versa.
What is a hot deck cold deck system.
Refer to photo 3 which illustrates damper actuators on a smaller mz system.
Typically the ahu controller also resets the hot deck and cold deck setpoints and controls the zone mixing dampers.
Cool air through duct work to a terminal box.
Maintenance or operational staff will be able to advise whether a system is a hot deck cold deck type.
Cold decks for providing heating and cooling capabilities simultaneously.
The damper blades for the hot and cold decks are linked together and offset by 90.
Some multizone units control one deck or the other in a multipoint arrangement such that the nearest to full heating controls hot deck temperature.
And 42 degree f.
Hot cold deck systems are found in older office buildings and in institutional buildings but are largely indistinguishable from other ahu based systems to the non technical observer.
In some systems this control may remain for example where the signal is a function of the thermostat branch line pressure.
As the call for heating reduces from full heat the hot deck starts to close the bypass.
The hot deck is reset based on the zone.
In other systems the signal may.
Hot air and 55 degree f.
As the signal approaches 0 the bypass deck is closed the hot deck is fully open and the fan is at full speed.
Temperature reset program is applied to dual duct systems and multizone hvac systems.
It explains how to use the ahu to reset the hot deck and cold deck setpoints.
The cold deck is always closed during heating.
As hot gas bypass will be required.
The dual duct air handlers take 180 degree f.
This application note is relevant when using an ahu to control a multi zone air handler.
Water and supply 100 degree f.
Each zone requires an actuator application.
The hot deck is halfway open and the fan ramps up to maintain pressure in the unit.
Systems utilize a parallel arrangement of heating and cooling surfaces commonly referred to as hot and.
The ahu had both a cold deck cd and a hot deck hd where both maintained a constant leaving air temperature maybe 55 f and 95 f respectively with mixing dampers mounted on the front or top of the ahu.
The hot deck setpoint and the cold deck setpoint operate respectively the water valves to the hot deck coil and the cold deck coil.