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 across the 24 V (ac) power supply
with an AC voltmeter. The reading should be between 22 and 26 V (ac).
Test The Powered Inputs
Boiler Demand
Measure the voltage between the boiler demand wire and the power wire that goes
to R+ of the control. The voltmeter should read between 21 and 27 V (ac) when the
boiler demand device calls for heat.
Test The Outputs
Boiler
Make sure power to the boiler circuit is off and short the boiler wires. When the boiler circuit is powered up, the boiler should
fire. If the boiler does not turn on, refer to any installation or troubleshooting information supplied with the boiler. (The boiler may
have a flow switch that prevents firing until the boiler loop pump is running). If the boiler operates properly, remove power from
the boiler circuit.
© 2019 tekmar 256_D - 09/19
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24 V (ac)
Class 2
Transformer
C
R
Ω
V
V
24 V (ac)
Class 2
Transformer
C
R
Ω
V
V
Boiler demand
switch
