Instruction manual

52
P/N HN-IOM-1 82-0331 Copyright 2009 Mestek, Inc.
Finned copper tube gas boilers & water heaters – Control manual
Situation Suggested procedure
Nothing happens when the power
switch is turned on.
Check 120VAC power on the service connector, J1. Verify power is connected per wiring diagrams. ❑
e Power switch light (ON -Position) should illuminate if power is wired correctly. If the light does not ❑
illuminate on the power switch, ensure that J7 is connected to the main board and the power switch.
If the Ignition Control is active, but the front panel display is inactive check: ❑
Cable and cable polarity from the control board to the display. 1.
J14 on the control board. 120VAC is routed from here to the transformer. e transformer returns 2.
24VAC to power the control.
Check for 120vac on the primary of the transformer and 24vac on the secondary. If one of the 24vac 3.
interlocks has been shorted to ground or the 24vac output is low, the transformer may be damaged or
a 24vac circuit may be miswired.
e HeatNet control is equipped with reseable fuses on the power input circuit. Wiring power incor- ❑
rectly to the unit will cause these fuses to open. Once the incorrect wiring is corrected, the fuses should
reset themselves in less than 5 minutes.
The display shows combustion air
damper failure.
If you are not using the combustion air damper then it needs to be disabled in the AUX FUNCTIONS ❑
menu.
e prove switch for the combustion air damper is not closing. Check to make sure the dampers are being ❑
controlled by the output relay you specied when programming for the damper. Also check to make sure
the prove switch is working properly.
If you are using SPARE 1 and you continue to get the error message aer the steps above, check the sensor ❑
TYPE specied in the SENSORS menu for sensor 5. If it is set to NONE, the controller will not recognize
the closed circuit. Set the Sensor type to ON/OFF.
The display is displaying random
characters or the control keeps
resetting.
ere may exist a grounding problem with the controller or one of the boilers, pumps, contactors or other ❑
devices connected to it.
If all grounding is correct, there may be an issue with radiated or induced electrical noise (interference). ❑
is may be caused by arcing across a contactor’s contacts when starting a pump motor or a large electrical
load. It may also be caused by the ignition transformer being improperly grounded or the spark gap being
out of adjustment.
Aempt to identify the noise source: ❑
What is the boiler/controller trying to do at the time of the failure? a.
Is the boiler on the same circuit as the noise source? (e boiler should have isolated power.) b.
Are shielded sensor wires used? (Ensure the shields are grounded only at the boiler control end.) c.
Are any sensors or sensor wires located near a transmiing antenna? (Move sensor)d.
There are no heating boilers on.
Check the seings for WWS SETPOINT and WARM WEATHER SHUTDOWN. ❑
If the outdoor air temperature is above the WWS SETPOINT and WARM WEATHER SHUT-a.
DOWN is set to YES, the circulator pump relay will be locked out and the heating boilers will not
re.
If the water temperature is within the heating band around the setpoint, boilers will not come on.b.
e water temperature must fall below the lower band limit to begin ring boilers.c.
Troubleshooting (continued)
9
Troubleshooting suggestionsTable 12