OM 931-6 • MicroTech III Unit Controller for WSHP
15
www.DaikinApplied.com
Microtech
®
III Unit Controller
Interface to External Equipment
■ The MicroTech III unit controller’s thermostat
input terminals may be directly interfaced with any
standard or night setback thermostat that uses
mechanical dry contacts. Power cannot be supplied
from the water source heat pump for electronic
thermostats that require a separate power supply
for their internal operation except hose provided
by Daikin. Only thermostats offered by Daikin are
proven to operate properly with the MicroTech III unit
controller. Daikin makes no guarantees about any
other thermostat or control device interfaced by the
end user with the MicroTech III unit controller.
■ Care must be used to isolate all external power
sources from the MicroTech III unit controller to
prevent ground loops and other unpredictable
electrical problems. Only dry mechanical contacts
should be used to operate or interface with the
MicroTech III unit controller’s thermostat and or
control inputs. Use mechanical relays to isolate
two power systems when external equipment with
its own power supply is used to interface with or
control the MicroTech III unit controller’s thermostat
and or control inputs. For example, if you have
a Building Automation System (BAS), controller,
etc., and you wish to use a digital output from the
building automation system or controller that is
internally powered, then you must use an additional
mechanical relay (not supplied by Daikin) to isolate
the MicroTech III unit controller.
■ Due to the nature of triacs and other solid state
devices, triacs cannot be directly used to operate
the MicroTech III’s unit controller’s thermostat or
control inputs. To interface triacs or other solid
state switching devices to the MicroTech III unit
controller inputs, separate them from the board
using mechanical relays. To do this, use the triac or
solid state device to drive a mechanical relay (not
supplied by Daikin), then use the mechanical relay’s
dry contacts to drive the desired MicroTech III unit
controller input.
■ The MicroTech III unit controller’s valve or pump
request terminal {IV/PR (H8)} is an output signal
to external devices to allow water flow as required
by the heat pump. The IV/PR (H8) terminal follows
compressor operation inversely if connected to the
normally open terminal and simultaneously when
connected to the normally closed terminal. The IV/
PR (H8) terminal can be used as a signal to an
external pump or valve to enable flow to the unit. The
compressor start is delayed for 45 seconds after the
IV/PR (H8) output is energized.
Table 6: IV/PR(H8) Terminal and Compressor Operation
IV/PR(H8)
Compressor On
Compressor Off
Normally Open
24 VAC
0 VAC
Normally Closed
0 VAC
24 VAC
Appendix A
Operation and Maintenance of I/O
Expansion Module
Introduction
The I/O Expansion Module is a field-installed option. It
is an extension of the main board and provides extra
functionality to the MicroTech III control system.
The I/O Expansion Module has 4 main purposes:
■ The MicroTech III unit controller in combination
with the I/O Expansion Module will be the standard
control system for two stage Water Source Heat
Pump equipment.
■ The I/O Expansion Module has outputs to control
boilerless electric or supplemental electric secondary
heating options on a standard Water Source Heat
Pump.
■ The I/O Expansion Module has outputs for multi-
speed fans on a standard Water Source Heat Pump.
■ The I/O Expansion Module has an independent LED
annunciator to identify operational fault conditions on
second stage equipment.
Adding an I/O Expansion Module (with an interconnect
cable) to the main controller allows two stage operation
of the water source heat pump.
Features
Standard Heat Pumps / Single Circuit Units
■ Monitors entering water temperature for
boilerless electric heat control
■ Outputs for medium and high speed fan controls
Second Circuit
■ High pressure switch
■ Low pressure switch
■ Low suction line temperature sensor
■ Compressor output
■ Reversing valve
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