Reheat output, Digital input – Honeywell EXCEL 10 W7752D User Manual

Page 16

Advertising
background image

EXCEL 10 FCU CONTROLLER LNS PLUG-INS USER GUIDE

EN2B-0285GE51 R0909

14

Fig. 10. Three-stage heating/cooling switching (defaults for switching levels and hysteresis shown)

Reheat Output

W7752D and F Controllers and the W7754P1000 have an

additional high-current (10 A max.; UL916: 6 A max.) output

relay to control an electric reheater (refer to Fig. 2 for sample

application). The reheat output has its own switching level and

hysteresis settings (see Fig. 11). The reheat relay may also

be used as an auxiliary output for other purposes, in which

case the controller must be configured to specify that the

output is under network control instead of the FCU control

algorithm.

Fig. 11. Reheat switching and hysteresis (defaults

shown)

Digital Input

The Excel 10 W7752 FCU Controllers are equipped with a

single digital input which may be configured to accommodate

an occupancy sensor, a window open/closed contact, an air

flow detector (for fan failure detection), or a changeover input.

It is possible to configure this input for either normally-open or

normally-closed contacts for any of the switches.

The control algorithm in the Excel 10 FCU Controller uses the

occupancy sensor, if configured, to determine the effective

occupancy mode (see Table 3). If the Time Of Day (TOD)

schedule indicates an occupied state, and the eccupancy

sensor contact is closed, the effective occupancy mode will be

"occupied". However, if the TOD schedule indicates an

occupied state and if the occupancy sensor contact is open,

then the effective occupancy mode will be "standby". The

control algorithm will then control according to the "standby"

setpoints configured for the heating and the cooling modes.

Configuring the digital input for movement or no movement

(dependent upon normally-open or normally-closed contacts)

adds a delay of 15 minutes to the occupancy sensor such that

the space is considered occupied until 15 minutes has

elapsed since the last movement is detected.

If the digital input is configured to read input from a window

open/closed contact, heating, cooling, and fan control will be

disabled while the window is detected open. Frost protection

will be enabled. A set of contacts may be wired in series for

multiple windows. If the window open/closed contact is not

configured, a one-to-one association (binding) of the window

sensor from another controller on the L

ON

W

ORKS

network can

be made. A locally-wired contact can also be used in

combination with the network input, the result being a logical

OR of the inputs.

If the digital input is configured to read input from an air flow

detector (fan status), heating and cooling control will be

disabled for a fan failure (fan ON and no air flow detected).

The input may also be configured for changeover for a two-

pipe system.

The Excel 10 W7754 FCU Controllers are equipped with a

second digital input which is permanently assigned (i.e. not

configurable using the plug-in) to the window contact function.

Advertising