9.0 Fault Finding; 10.0 Servicing - Hamworthy MILBORNE381 Series Design Installation, Commissioning And Operating Instructions

9.0 FAULT FINDING

The Milborne boiler is equipped with full self-diagnostic fault indication, with faults allocated a code, which is
displayed (flashes) on the screen - refer to section 8.6
The common fault codes are detailed in section 8.6. Fault codes not detailed in this manual should only be
investigated by an Engineer.
Should a fault code appear which cannot be reset, or a fault code repeatedly occurs, contact Hamworthy
Heating for assistance. Do not continue to operate or use the boiler as this may cause damage to the
controls.
9.1 Safety Features
9.1.1 Temperature Limit Thermostat The electronic control thermostat has several safety levels built in such
that controlled shutdown should occur before the limit thermostat is activated requiring manual reset. Should
these safety levels be overridden (say external pump overrun failure after shutdown, or operation of the module
on/off switch during operation), the temperature limit thermostat will trip initiating a boiler lockout, preventing the
boiler from firing. An error code will be indicated on the display (A17) which will require the control to be reset
(S1), once the boiler has cooled sufficiently. An investigation should be carried out to ascertain the reason for the
overheating. An obvious reason would be low or no flow through the heat exchanger.
9.1.2 Flame Sensing The flame is under constant supervision by the burner control. This is accomplished by
measuring the flame's ability to rectify an AC current. If the flame diminishes for whatever reason, the rectified
current drops until such that it is below the control threshold (2μA) and the boiler will shut down and will perform
up to 5 ignition attempts. If the boiler has failed to light it will go to lockout an error code will be indicated on the
display (A01) which will require the control to be reset (S1). If the boiler continues to lockout, an investigation must
be made to ascertain the cause—refer to section 9.3
9.2 Fault Finding Procedures
General error codes are detailed in section 8.5 to assist with general fault finding. If the boiler still cannot operate
satisfactorily after following the instructions, consult Hamworthy Heating for assistance.
9.3 Possilbe Causes of Boiler Lockout
1) Ignition failure due to faulty igniter.
2) Ignition failure due to faulty gas valve.
3) No or low gas supply pressure.
4) No ignition due to faulty controller.
5) Ignition failure due to faulty flame probe or sensing circuit.

10.0 SERVICING

A competent person registered for working on non domestic gas appliances should check and ensure that the
flue, its support and terminal, the ventilation to the boiler house, safety valve, condensate trap, drain, water
filter if fitted, pressure gauge etc., are in a serviceable and working condition, and still comply with the relevant
standards and codes of practice - see Section 4 & Appendices
10.1 Regular servicing is recommended, preferably by a Hamworthy appointed person, and at least annually, to
ensure trouble free operation.
For the Milborne boiler, Hamworthy would recommend an additional 6 monthly examination following commissioning,
acknowledging site conditions and running hours.
Although cleaning of flueways may not be necessary on a yearly basis inspection of the flueways must be undertaken
annually and it is important that all controls and safety features are checked for correct operation.
NOTE! Measuring flue gas CO and gas temperatures will give an indication of the state of the boiler flueways and
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waterways. Results should be compared with previously measured values to establish possible loss of efficiency.
Should remedial work be carried out on a module within a bank of boilers, then the non-firing module must be
electrically isolated so as to prevent accidental operation., in the event that the installation is required for
ongoing heating requirements.
10.2 The procedure detailed relates to a single module and must be carried out on all modules within a bank of boilers.
Before servicing the boiler, the following procedure must be carried out: -
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HAMWORTHY HEATING LTD MILBORNE 500001130/J