Morco FEB-24E UK User manual

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FEB-24E UK SUPERCOMPACT
COMBINATION BOILER
TECHNICAL & FAULTFINDING GUIDE
Morco Products Ltd
Riverview Road, Beverley, East Yorkshire, HU17 0LD
Telephone [phone] Fax [phone]

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Contents
1. Quick Guide to Trouble Shooting
2. Electrical Components
3. Central Heating Logic Programme
4. Explanation of Self Diagnostics
5. Self Diagnostic Flow Charts
ISSUE NUMBER 1.0

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1. Quick Guide to Trouble shooting
This section outlines the most common problems and helps to guide you through the rest
of the workshop manual. (Read this section first, before you make any adjustments. It
will save you time.)
CHECK HOT WATER SYSTEM FIRST, BEFORE THE CENTRAL HEATING CIRCUIT
HOT WATER SYSTEM
Here are some common problems:
GAS REGULATORS
Single appliance low capacity gas regulators plus 3/8” flexible low pressure pipe, will
reduce the efficiency dramatically. Ensure gas regulators and pipes are capable of
delivering 37mbar at the inlet under full load. A 2.5mbar drop is acceptable.
WATER FILTER
Check for contamination with foreign objects such as sawdust, plastic pipe swarf, etc. The
water filter is located inside the cold water inlet fitting under the boiler. Any blockage will
reduce flow and may prevent the boiler firing up.
HOT AND COLD WATER CONNECTIONS
Connections may be reversed at the boiler inlet/outlet fittings, resulting in the boiler failing
to commence ignition sequence. This is because the hydraulic valve operates in one
direction only.
THERMOSTATIC SHOWER MIXER VALVE
Faulty non return valves within the mixer tap may allow mains cold water to enter the
domestic hot water pipe work. The boiler will react to the situation according to the
amount of mains water entering the system. In severe cases a high percentage of mains
cold water will exit the hot water tap in place of hot water, as water will always take the
path of least resistance. This will result in no hot water flow, or a very restricted flow
through the boiler. This will result in no ignition occurring or the boiler will modulate at very
low gas pressure, followed by the boiler eventually shutting down as insufficient flow
passes through the boiler.

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QUICK PLUMBING CHECK
A simple solution if cross contamination of hot and cold water is suspected, is to
disconnect the hot water outlet pipe from the boiler (under the van), this procedure
eliminates faulty mixer valves and crossed pipes from the system and will allow the boiler
to operate without any water starvation or back pressure. If it works, you now know the
plumbing system is at fault and not the boiler.
WATER SUPPLY
The FEB24E Combination Boiler delivers up to 10 litres/minute of hot water. Many sites
depending on occupancy levels and season do not have a mains system capable of
supplying a constant pressure/flow rate to the boiler. Should the pressure/flow rate of the
incoming mains cold water fall below the minimum specified values, the boiler will shut
down due to the domestic hot water (DHW) thermistor detecting a temperature greater
than 70 deg C or the micro-switch deactivating under low flow. Pressure at the cold water
inlet can be checked using a gauge attached to the filling loop valve on the installation pipe
work. The pressures should be checked when the domestic hot water flow is at maximum
(10 litres/min). This can be adjusted at the faucet. If max flow cannot be achieved through
the faucet, there is either a blockage or the water supply is inadequate.
CENTRAL HEATING SYSTEM
Check the following first:-
ROOM THERMOSTAT – (if fitted)
Faulty connections or incorrectly wired room thermostats result in the central heating not
working. The fault is usually at the room thermostat, but can also occur at the connector
block on the boiler, due to the insulation not being removed from the conductor wire or a
loose feed wire (2 black) at the base of the connector.
LOW PRESSURE ON GAUGE
Incorrect or too low a pressure in the heating circuit will disable the boiler in both central
heating and hot water modes. FEB24E boilers are fitted with a pressure switch, should the
pressure within the heating circuit fall below 0.8 bar the switch will become open circuit
and the boiler will lock out. Fault code 2 will be displayed via the LED. This will prevent
damage to the boiler in the event of the heating system leaking, or in some cases due to
accidental drain down of the heating circuit.
Important- The accuracy of pressure gauges may vary and can provide a general
indication of pressure within the boiler only. Pressure will also vary according to
temperature. The normal operating pressure when cold should be 1.6bar.

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Important - Leaks on the heating circuit can occur anywhere on the system. It is important
to locate and rectify any leak however small it may be. One way of detecting minute leaks
is to pressurise the boiler to 2.0bar. Using toilet or tissue paper, wipe around any joints on
the system. If any moisture is present then the tissue will change colour becoming darker.
Check the following if low pressure is shown:
Radiator air vent screws and blanking plugs
Radiator valves all joints and unions
Filling loop double check valve
(This may not be visible without removing inspection panels)
Boiler connections including safety valve (check discharge pipe)
Automatic air vent bleed screw (located on top of pump)
Drain plugs and connections under the van. Any leaks are usually indicated by
dark patches on the concrete or gravel, or look for patches of dead grass.
Loss of pressure from expansion vessel (see section under expansion vessel)
If the leak is impossible to detect then the last resort is to introduce a proprietary leak
sealing chemical into the system such as Fernox LS 3.
TIME CLOCK
Check that the time clock is calling for heat, the white tappets should be in the outer
position at the arrow head.
IMPORTANT. The specification of time clocks on boilers after serial number 050512656
incorporates a three position selector switch located at the base of the clock. There are
three positions as follows:
1. Switch to the left overrides timed positions and heating is on constant.
2. Switch in the centre position heating is on or off according to tappet timed
positions on the clock
3. Switch to the right heating is off.
HEATING SLOW TO REACH TEMPERATURE
The main burner may ignite for short periods only and the radiators may be slow to heat.
This can be caused by a blocked filter on the central heating return pipe. (Right hand
pipe). Access to the filter requires draining down the boiler, and removing the pipe fitting
from the boiler. The filter can then be removed for cleaning and MUST be replaced to the
boiler.

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Another associated problem with sluggish radiator performance can be attributed to un-
circulated undiluted anti freeze in the boiler and pipe work. This problem is usually worse
in cold conditions. In order to cure the problem, try the following method.
1. Turn off one radiator valve on the largest radiator. Increase the pressure in the
system to 2.0bar. Now release 0.5 litre of fluid from the air vent cap on the radiator
into a container.
2. Close the vent and re-pressurise the heating circuit to 2.0bar and open the radiator
valve which was closed on the initial purge. Close the valve previously open (you
will need a screw driver and adjustable spanner to open and close the lock shield
valve). Release another 0.5 litre of fluid from the air vent cap. This procedure
should have cleared any concentrated anti freeze from the pipe work.
3. Re-pressure the boiler to 1.6bar and open both the radiator valves fully and run the
heating. Once the boiler has established full heat at the radiator, close one of the
valves on the working radiator. Other radiators should now slowly start to heat up.
Radiators which fail to heat up may require purging as above.
4. If time is not a problem, simply leave the heating on. After an hour or two the
problem will clear itself.
COLD RADIATORS
These usually appear in pairs, due to crossed pipe work, i.e. one radiator is fed with two
flow pipes with a second radiator fed with two returns, and consequently neither radiator is
capable of circulation and remains cold.
Always check that the valves are open. Some systems are not heat tested before
despatch, and it is possible that the valves may be closed very tightly. If in doubt check by
removing the plastic head and use a spanner to open the valve.
THINGS TO CHECK BEFORE MAKING ANY ADJUSTMENTS
1. Mains cold water supply valve fully open.
2. Gas installation correct. Regulator/pipe size correct/UPSO/OPSO working
correctly.
3. Gas supply valves open/isolation valve on boiler fully open.
4. Power supply to boiler socket present.
5. Air pressure switch test point cap fully located. (Black rubber cap on the right hand
side on the top of boiler)
6. Correct water pressure is in the heating circuit (1.6Bar when cold)

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AT THE BOILER, REMOVE THE FRONT COVER AND CHECK THE FOLLOWING:
The 2 white modulation solenoid wires are connected
The spark generator is attached to the gas valve correctly
Both the H.T leads from the spark generator are attached correctly
Look for wires and components not connected or plugged incorrectly, especially the
clip on central heating thermistor which should be attached to the heating flow pipe
and not the gas pipe!
IMPORTANT: Boilers with serial numbers 050410747 onwards will have the central
heating thermistor located on the left hand side of the main heat exchanger.
Important Things You Will Find in the Technical and Faultfinding Manual
Domestic Hot Water Ignition Sequence (Page 28)
This flow diagram represents the general operating system in the domestic hot water
mode and the sequence of events if temperatures exceed the specified limits which are
pre-determined by the PCB.
Central Heating Ignition Sequence (Page 29)
This flow diagram represents the general operating system in the central heating mode
and the sequence of events if temperatures exceed the specified limits.
Please note that following the initial 30 seconds of minimum output, modulation may not
occur for a further 5 minutes if the central heating logic programme is operating. This is
because the boiler will not fire on full power if it has detected it is serving a system with a
low load. This is the case in most caravan holiday homes. For more detailed information
please see the note on central heating logic programme. (Page 25)
Lighting Up Sequence Flow Diagram (page 27)
The lighting up sequence is common for both the central heating and domestic hot water
modes. Once the flame is established the relevant regulation on modulation takes place.
Explanation of Self-Diagnostics (Page 30)
Whenever a fault develops in the boiler that is likely to affect its safe operation it will lock
out and show a fault code via a flashing sequence on the red LED on the control panel.
Lock out faults will require a component to be replaced or service work to be carried out.
Identify the fault by reading the flashing LED sequence (self diagnostic fault code). Each

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fault code has a description as to the cause of the problem in the workshop manual – read
this carefully.
N.B. there will be a time delay of between a few seconds and 3 minutes between the boiler
locking out and showing the self diagnostic fault code. The workshop manual shows each
component of the boiler, a functional description and the operating voltages where
applicable. By reading this information and testing before replacing components the
correct diagnosis can be reached ensuring that the wrong part is not replaced
unnecessarily.
Fault Finding Flow Diagrams (Pages 39 – 46)
These diagrams help diagnose problems that are not related to the safe operation of the
boiler and hence are not subject to the “lock –out” mechanism and the corresponding self
diagnostic fault code. The diagrams are to be used as a guide only and in conjunction with
the more detailed information on each component found elsewhere in the workshop
manual.

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