Ideal Boilers (caradon ideal)


Classic Combi and Classic NF


Problem Solution
Boiler cycling on/off Wax thermostatic capsule on flow pipe can stick, preventing heating from coming on
Pressure problems

Flexible pipe to vessel can block causing pressure swings up and down

Overheating in water mode

The internal bypass may be blocked, there is no pump over-run on this model, so after demand the residual heat goes through the bypass by gravity


Isar Range (M30/100 and HE Models)


Problem Solution
HF. (there is a dot after the HF) Detection probe error, or lead has shorted to earth
Display symbol meanings

0= No demand at rest

t=Preheat from cold

d=hot water demand, or preheat on later models

C=central heating demand

3 dashes in display

Appliance has overheated, may have been an L9/H9 overheat prior to this. Check operation of pump, make system is filled and vented, may be a restriction in plate heat exchanger causing overheat

PCB Fuse blowing,

House RCD tripping

Overheat thermostat/wires can short to earth,check wiring harnesses inside combustion chamber for heat damage. Check for water ingress on or around diverter valve

Water leaks

Washers on plate heat exchanger go brittle and can leak intermittently

Check S trap is not blocked

Auto air vents can leak, check for signs of green/staining on auto air vent

Heat exchanger can leak condensate from seams after a short period in operation, also check for CO/CO2 readings inside the combustion box around the base of the heat exchanger when in operation

H5 fault Check the internal jumpers on the PCB are fitted correctly and not misaligned
Blank user display

After checking power to main PCB, suspect main PCB has gone

Check user controls housing and purple wire as smallest bit of moisture can cause poor connection

Droning/Kettling Noise

Check S Trap and sump are clear, check condensate pipework for blockages

Gas valves can also make a loud 'jubbering' noise if faulty


Faulty hot water sensor

Pumps/Diverter Valves

There are three different pumps and diverter valves on these models, make sure if you need a replacement that you order the correct ones.

Diverter valves include; red top, grey top, black top

Pumps include; Myson CP61, Myson CP61W(also fits WILO), Grundfos 15/60


Mini Combi Range C24,28,32


Problem Solution
Flow Fault Small differential hole in primary flow switch housing can block right at the back, carefully remove small brass'pip' with a screwdriver (this does screw out), and use a small ball ended allen key to clean out the hole
Boiler on no demand

Water flow switch can stick, make sure the boiler is not in frost potection mode




Problem Solution
Explosive Ignition Weak Spark from generator, check electrode gap,

Water flow switch can stick, oring from the flow regulator can make switch stick on by jamming in switch

Blowing fuses, tripping RCD

Low water pressure switch can leak internally and cause electrical issues/blowing fuses/tripping RCD