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Hydronic Heating Boilers and
Domestic Water Heaters
62
Check the flow switch and
Tekmar
pi
ns #15 and #16
for 24VAC.
Step 1
Does the power switch
provide power to the unit?
Check the switch for proper
operation. Check the line voltage.
NO
YES
Check 24VAC at TH
(orange wire) on the
ig
nition module.
YES
Check all safety limit
devices, all connectors
behind the control panel
and voltage from the
transformer to B2.
NO
YES
YES
Exchange ignition
module.
Check staging
relay (S2). Is
there 120VAC on
the red wire to the
fan?
NO
YES
Replace
relay.
Replace fan.
YES
Prepurge light comes on.
Status light does not
blink 1 flash continuous.
Step 3
Check
air pres
sure
switch 24VAC on tan
wire (N.O.).
NO
24VAC at PS (tan wire)
at ignition
module and/or connector plug for
proving relay s
e
cure.
NO
YES
Check air pressure
switch for correct
pressures.
Replace air pressure
switch.
Correct air settings.
May have to clean
burners/heat
exchanger.
YES
Trial for ignition completes
and gas valve(s
) opens. Does
not go into flame failure.
N
O
Check amp draw
f
or
3.1 amps.
NO
Is air switch
bouncing?
YES
Replace igniter if les
s th
an 2.75 amps.
YES
YES
NO
Combustion
air blower
comes on.
NO
Does F2 on ignition module
have 120VAC?
YES
Is there 24VAC at B2
on the terminal strip?
Step 2
Step 4
NO
NO
Gas
valve(s
) stays open
a
nd is g
etti
n
g 24VAC.
Step 5
NO
Check inlet gas pressure
both static and dynamic.
Check manifold p
ressure.
Check draft. Check air
pressure.
YES
Is the flame sen
se signal to the
ignition module 5uA dc or greater?
NO
Replace gas valve
.
Check ig
ni
tion m
odule pin #05
(repla
c
e
RLY2402 if no
voltage).
Unit is
running.
NO
NO
Is 24VAC present at main unit
connector (
3x
3
amp plug) red
wire?
YES
TROUBLESHOOTING GUIDE
399,999 - 750,000 Btu/hr Models