Electronic Air Cleaner (Eac) Connections; Dehumidify Capability With Standard Humidistat Connection; Operation; Start-Up - Dettson DCAH Série Guide D'installation

These terminals are energized with 24 VAC when G
thermostat signal is present.
2.8.2 ELECTRONIC AIR CLEANER (EAC)
CONNECTIONS
Fan Control Board terminals AUX1 and AUX2 are provided
for direct connections to the low-voltage control of an
electronic air cleaner. These terminals are energized with 24
VAC when G thermostat signal is present (refer to Figure 8).

Figure 8 : Electronic air cleaner connections

2.8.3 DEHUMIDIFY CAPABILITY WITH STANDARD
HUMIDISTAT CONNECTION
Latent capacities for systems using this unit are better than
average systems. If increased latent capacity is an
application requirement,
connection terminal (DH) for use of a standard humidistat.
The unit control will detect the humidistat contact opening on
increasing humidity and reduce its airflow to approximately
80% of nominal cooling mode airflow. This reduction will
increase the system latent capacity until the humidity falls to
a level which causes the humidistat contact to close its
contacts.
3.0

OPERATION

3.1

START-UP

Before starting up the unit, be sure to check that the
following items are in compliance:
The main electrical power is conform to the information
1.
on the nameplate;
The unit is properly grounded;
2.
With main power disconnected, verify that the blower
3.
wheel is well fixed on the motor shaft and the wheel
turns freely;
Verify all coils, valves and piping are leak free and
4.
insulated if required;
Insure all air in the hot water loop is vented to prevent
5.
premature pump failure;
Make sure all panels are installed. A safety switch
6.
prevent the start-up of the blower if the blower door
is not installed;
The air filter is installed on the return duct and in
7.
proper direction;
All dirt and debris are removed.
8.
3.2

HEATING START-UP :

DNS-1154 Rev. A
DNS-1154 Rev. A
the field wiring provides
1. Fill the water heater. Open a hot water faucet to vent all
air in the water heater. Close faucet when all air is
vented.
2. Start the water heater and set the temperature to 140F.
3. Close inlet water shut-off valve to the heating coil.
Open the return water shut-off valve. Open the drain /
vent valve. When all air is vented, close return water
shut-off valve and reopen the inlet water shut-off valve.
Redo this procedure until all air has been vented out
the heating coil. Close drain / vent valve. Open both
shut-off valves.
4. Set the room thermostat in heating mode and adjust
temperature above ambient temperature. If the pump is
in function but there's no circulation, open the drain /
vent valve until all air is completely vented.
5. The water heater temperature shall be readjusted as
near to 140F until the temperature has stabilized.
3.3 OPERATING SEQUENCE – VARIABLE

SPEED ECM MOTOR

The blower motor is a true variable speed motor designed to
deliver constant CFM. Constant CFM is valid for systems
with total external static pressure between 0.1 and 0.7 inches
water column.
a
3.3.1

CONTINUOUS FAN

•
Thermostat closes circuit R to G.
•
Blower runs at continuous fan airflow.
3.3.2 COOLING MODE – SINGLE STAGE
•
If indoor temperature is above temperature set point and
humidity is below humidity set point, thermostat closes
circuits R to G, R to Y/Y2 and R to O.
NOTE: For single stage systems, do not use the Y1 terminal.
•
Unit delivers single stage cooling airflow.
3.3.3 COOLING MODE – TWO STAGE
•
First stage (low) cooling: Thermostat closes circuits R to
G, R to O, and R to Y1.
•
Unit delivers low stage cooling airflow.
•
Second stage (high) cooling: Thermostat closes circuits
R to G, R to O, R to Y1 and R to Y/Y2.
•
Unit delivers high stage cooling airflow.
3.3.4 COOLING MODE – DEHUMIDIFICATION
NOTE: Remove jumper « J1 » on board to activate this
function. (Refer to Figures 6 and 11)
•
If indoor temperature is above temperature set point and
humidity is above humidity set point, thermostat closes
circuits R to G, R to Y/Y2 and R to O and humidistat
opens circuit R to DH.
•
The unit delivers airflow which is approximately 80% of
the nominal cooling airflow to increase the latent
capacity of the system.
3.3.5

HEATING MODE

•
Thermostat closes circuit R to W1 or W2.
•
Unit delivers the selected heat airflow.
8