Ideal HE24 Boiler Central Heating Problem

[jimmymak]

Hi Guys
I am not a plumber I'm a sparky,

I have a Ideal HE24 Boiler with a Central heating problem, the central heating won't start the Domestic water is fine no problem what's so ever.
I have trawled the forum sites on the net looking for a fix for this fault and found it to be a common occurrence with this boiler but no definite answer to fix it.

My problem starts the same as many others do. The letter 'C' for “central heating” appears in the window but the light just flashes and fails to ignite the boiler. BUT the domestic water heats when called for with no problem.

I have been lucky to have had access to some new spares for this boiler so have eliminated a few faults which the manual suggests.

I started with all the common faults first Batteries, room thermostats, timers, by passed thermostat shorting out in boiler, Changed thermistors flow and return and overheat thermostat. Circulating Pump is Free, New diverter valve fitted, Tried brand new out of box PCB, Still no Joy.

Whats the next thought

 

[mickie]

ideal what ? i'd be able to help you if i knew what the inside of the boiler looked like

 

[jimmymak]

Ideal Isar he24

 

[armourer]

Im guessing its an Isar HE24 and my next guess would be to stop throwing parts at it and get a heating engineer in.

 

[mfgs]

One of the worst boilers ever made, get a gas engineer or one of ideals engineers out. It could be anything on this boiler.

 

[jimmymak]

Bye gum mikie lad that didn't tek long foh they to be defeated ya not a boxer lad ya can't throw towel in that easy, get told thinking cap on

 

[diamondgas]

jimmymak, what colour is the water when you bleed a radiator?

Swapping parts willy-nilly sorts jack! But costs a bit unless you know someone... But then if you know someone you wouldn't be here! lol

 

[jimmymak]

Diamondgas, what colour is the water when you bleed a radiator?

It's crystal clear

 

[diamondgas]

Did you change the whole diverter or just the head? It sounds like the valve is stuck in the hot water position! If not that then check the isolation valves are open and all your radiators are turned on! Sounds like heat isn't leaving the boiler yeh?

 

[jimmymak]

I changed the complete diverter although the old one was OK. Yep all is in order valves open etc.

The water does leave the boiler but this was not heated by the central heating mode.

When the boiler heats the domestic and no further call for hot water from the tap is required and if the central heating thermostat calls for heating the now body of hot water heated from the domestic call is released into the central heating system by means of the Diverter valve.

 

[jimmymak]

When changing over from domestic mode to central heating the boiler shuts down after domestic call taps not extracted the boiler then changes to CH Mode the boiler then seems to start to fire up but this is for a 2-3 second period then shuts down. hope this is of any help

 

[diamondgas]

I changed the complete diverter although the old one was OK. Yep all is in order valves open etc.

The water does leave the boiler but this was not heated by the central heating mode.

When the boiler heats the domestic and no further call for hot water from the tap is required and if the central heating thermostat calls for heating the now body of hot water heated from the domestic call is released into the central heating system by means of the Diverter valve.

And you're saying at this point the 'c' continues to flash and there's no attempt of ignition .... just to clarify yeh? Next step I'd be doing is linking out all external controls on the main plug under the boiler L1-L2 to eliminate external controls! If you know for definite the diverter spindle is moving out and the boiler isn't igniting I'd be inclined towards the user control stat

 

[jimmymak]

Next step I'd be doing is linking out all external controls on the main plug under the boiler L1-L2 to eliminate external controls!

Yep being a sparky this was my first thing to eliminate No joy

 

[jimmymak]

DIAMONDGAS ....and the boiler isn't igniting I'd be inclined towards the user control stat

I was thinking the same not many more things to go for

 

[diamondgas]

The symptoms you describe are classic sticking diverter which is why I'm harpin on about it .... Pull the head off the diverter .... Is it red or grey, by-the-way? ... Anyhoo's remove the valve head, spindle out is C/H position I believe ... Control stat on maximum and see what happens. From cold it should fire up instantly however the boiler does have an anti cycle on it so you may have o wait a couple of mins B4 is lights ... All said if it doesn't light then I'd be changing the user control ...

 

[diamondgas]

DIAMONDGAS ....and the boiler isn't igniting I'd be inclined towards the user control stat

I was thinking the same not many more things to go for

Sounds the most likely cause yeh?

 

[jimmymak]

Yep I appreciated, diamondgas, The symptoms you describe are classic sticking diverter which is why I'm harpin on about it.

but the old and new are working fine and yes it's the grey unit both diverters.

 

[armourer]

what about the diverter actuator?

Remove the actuator head and manually operate the diverter valve to check flow, with the pump running and CH calling for heat you should be able to hear the flow into the pipework.

 

[jimmymak]

Hi armourer
The pipe work does get hot it is circulating through the system, when the hot water in the reservoir of the boiler is empty unheated water is circulating through the pipes

 

[armourer]

Are you are sure the pump is running correctly (remove the bleed screw with a cloth underneath and put a small screwdriver inside to feel hear the impellors turning) as mentioned before try user control stat? Tricky one this.

If the pump is not running correctly you will still feel heat in the flow pipe (By the boiler) just not enough to take it away from the boiler and it will shut down on the temp stat.

 

[diamondgas]

Are you are sure the pump is running correctly (remove the bleed screw with a cloth underneath and put a small screwdriver inside to feel hear the impellors turning) as mentioned before try user control stat? Tricky one this.

If the pump is not running correctly you will still feel heat in the flow pipe (By the boiler) just not enough to take it away from the boiler and it will shut down on the temp stat.

If the pump wasn't working the OP would have no hot water armourer ...

 

[jimmymak]

The Hot water does extent to the radiators downstairs and the first floor if I keep repeating the domestic charge

 

[jimmymak]

Have a user control in the pipeline let you know the outcome next week

take care

 

[arran197]

If it was the pump, I think the Isar comes up with a fault code. I'm not sure how they work these Isar's, not really worked on them that much. But my little experience has told me they are shocking boilers!

 

[armourer]

If the pump wasn't working the OP would have no hot water armourer ...

I was thinking not working efficiently. eg. broken impeller blade so enough to get it through the plate heat ex but not away from the boiler