tekmar 268 Boiler Control - Manual (Page 20)

© 2010 D 268 - 11/10 20 of 32
Setpoint Demand
If a setpoint demand is used, measure the voltage between the
Setp / DHW and the Com Dem terminals (8 and 7). When the setpoint
demand device calls for heat, you should measure between 20 and
260 V (ac) at the terminals. When the setpoint demand device is off,
you should measure less than 5 V (ac).
2 1
Com Boil
Sup
10 9
Power
L N
103.5 to 126.5 V (ac)
7 6
Com
Dem
Boil
Dem
20 to 260 V (ac)
UnOccupied Switch
If an external timer (tekmar Timer 032) or switch is used, connect the two wires from
the external switch to the Com – and UnO Sw terminals (1 and 5). When these two
terminals are shorted together, the control registers an UnOccupied signal.
STEP FIVE
——————
TESTING THE WIRING
General
Each terminal block must be unplugged from its header on the control before power is applied for testing. To remove the terminal
block, pull straight down from the control.
The following tests are to be performed using standard testing practices and procedures and should only be carried out by
properly trained and experienced persons.
A good quality electrical test meter, capable of reading from at least 0 - 300 V (ac) and at least 0 - 2,000,000 Ω, is essential to
properly test the wiring and sensors.
V 20 to 260 V (ac) 7 8
Com
Dem
Setp/
DHW
Test The Sensors
In order to test the sensors, the actual temperature at each sensor
location must be measured. A good quality digital thermometer with
a surface temperature probe is recommended for ease of use and
accuracy. Where a digital thermometer is not available, a spare sensor
can be strapped alongside the one to be tested and the readings
compared. Test the sensors according to the instructions in the Data
Brochure D 070.
Test The Power Supply
Make sure exposed wires and bare terminals are not in contact with
other wires or grounded surfaces. Turn on the power and measure the
voltage between the Power L and Power N terminals (10 and 9) using an
AC voltmeter, the reading should be between 103.5 and 126.5 V (ac).
Test the Powered Inputs
Boiler Demand
If a boiler demand is used, measure the voltage between the
Boil Dem and the Com Dem terminals (6 and 7). When the boiler
demand device calls for heat, you should measure between 20 and
260 V (ac) at the terminals. When the boiler demand device is off,
you should measure less than 5 V (ac).
DHW Demand
If a DHW demand is used, measure the voltage between the
Setp / DHW and the Com Dem terminals (8 and 7). When the DHW
demand device calls for heat, a voltage between 20 and 260 V
(ac) should be measured at the terminals. When the DHW demand
device is off, less than 5 V (ac) should be measured.
1
Com
2
Boil
Sup
3
Boil
Ret
4
Out
5
UnO
Sw