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Tx I&O Manual
68
Table 17-3
Lockout and Error Code Descriptions
Code
Description
Loc 0
E2PROM Error
– if problem persists, replace main control board.
Loc 1
Ignition Error
– five unsuccessful ignition attempts in a row; perform the following checks:
1.
If a new installation, and the burner ignites but immediately goes out, then check polarity of
the120VAC power supply.
2.
Check venting for blockages.
3.
Check condensate trap from proper draining.
4.
Static gas pressure – if insufficient check gas supply-lines and regulator.
5.
Gas pressure during ignition – if the static gas pressure is sufficient, check pressure during ignition
sequence, i.e. when gas valve opens.
a.
If pressure drops below minimum (4” for NG / 8” for LP), check gas supply-line and regulator.
b.
If pressure does not move, verify 120VDC at valve during ignition; if no power, check wiring
– replace control; if power is present – replace gas valve.
c.
If pressure drops slightly – proceed to next step
6.
Unit ignites but immediately goes out – check flame sensor (clean or replace) and flame sensor
cable, clean combustion chamber, replace control. If a combustion analyzer is available, adjust
throttle screw out 1 turn – check/adjust combustion once unit is operational.
7.
Unit fails to ignite – check spark electrode and cable (replace). Verify the spark electrode is arcing.
WARNING!! – maintain clearance from ignition components while the power is on to avoid
risk of severe electrical shock.
8.
Check spark igniter gap – gap between electrodes should be
3
/
16
to ¼ inch.
9.
Ensure the gas regulator is a minimum of 6’ upstream of the gas valve of the boiler.
10.
Unit ignites and runs – check combustion at maximum and minimum modulation rates.
Loc 2 - 4
Gas Valve Circuit Fault (Safety)
– control has sensed a fault in the gas valve electrical circuit, check for a
loose connection in the gas valve wiring harness. Also see “Loc 5”.
Power Supply Electrical Interference –
see “Loc 6 & 7”
Loc 5
Limit Circuit Open (Safety)
– control has sensed a fault in the safety limit circuit; check the following:
1.
External Limit (Purple wire) – if an external limit device (i.e. LWCO) is connected to the purple
wire at the field wiring terminal, check to ensure it has not tripped, and that it is wired correctly.
2.
Internal Limit (Heat Exchanger Thermal Fuse) – the heat exchanger is equipped with a normally
closed thermal fuse [see Figure 19-1(a), item 48]; the fuse opens when the heat exchanger gets too
hot. If the fuse is open, the heat exchanger must be replaced.
3.
Bad Electrical Connection in Safety Limit Circuit – check J13 connections at the controller (purple
and yellow wires), and connections at the Thermal Fuse; the pins in the connector may be damaged
Power Supply Electrical Interference –
see “Loc 6 & 7”
Loc 6 & 7
Power Supply Electrical Interference –
check for poor line, neutral and ground connections in the wiring
leading to the boiler. Check the internal ground connections within the boiler. Eliminate sources of
electrical noise, i.e. welders, large pump inverters, etc. If power is being supplied by a generator, install
an appropriately sized UPS (Uninterruptible Power Supply). If source of problem cannot be located,
replace controller.
Limit Circuit Open (Safety)
– see “Loc 5”
Loc 8-9
Controller Malfunction
– contact NTI, check field wiring, replace controller.
Loc 10
Outlet Sensor Fault
– controller has sensed an invalid reading at the Clip-on Outlet sensor; check cable,
then replace sensor [see Figure 19-1(a), item 15].
Loc 11
Uncorrected Blocking Error
– a blocking error (Err) has lasted for 20 consecutive hours.
Loc 12
Incorrect Fan Speed
– measured fan speed is not reaching target fan speed within 60 seconds. Check
wiring to fan for loose connections. If fan is not turning on, inspect the inline Blower Fuse – replace if
necessary (see Figure 12-1).
Loc 13-24
Controller Malfunction
– contact NTI, check field wiring, replace controller.
Loc 25
Limit Circuit Open (Safety)
– see “Loc 5”.
Power Supply Electrical Interference –
see “Loc 6 & 7”
Outlet Sensor Detected Max Temp Reading
– verify proper water flow through the boiler, test Outlet
Sensor and Outlet Sensor cable for short circuit; see “Err 81”.
Loc 26
Flue Sensor Fault
– controller has sensed an invalid reading at the Flue sensor; check cable, then replace
sensor [see Figure 19-1(a), item 20].
