Problem with IDEAL ICOS HE24 boiler

Hi everybody, this is my first post.

I have a problem with my:

Boiler Ideal Icos HE24 (downstairs in the kitchen)
Grunfoss pump + big water tank + electronic controls steering module (upstairs in the cupboard)

Looks like central heating is from the boiler and hot water from the big tank (I think electric).

MY ISSUE:

Boiler status c burner led constantly flashing after a short while (5-10 min) the boiler fired up and the burner led switched to permanently on but after 60 seconds returned to flashing. It is happening constantly (over last 24h), pump is also working all the time. After switching of the boiler display shows "-" later "3" and later "c" and here we go again with 5min and 60 sec cycles.

Any advice and help is much appreciated.

Heating and hw will come from the boiler with electric back up.
Do the pipes get warm before and after pump.?
Is it a sealed system and is there water in it.?
Do you have 2 zone valves.?
Do all radiators have trvs?
Need lots more info, it sounds like heat not getting away from boiler and its overheating

Thanks for your interest, please see some answers below:

Do the pipes get warm before and after pump.? - YES
Is it a sealed system and is there water in it.? - YES
Do you have 2 zone valves.? - How do I find out?
Do all radiators have trvs? - thermostat valves YES but not in the bathroom.

bidonox said:

Do you have 2 zone valves.? - How do I find out?
Do all radiators have trvs? - thermostat valves YES but not in the bathroom.

Click to expand...

zone valves are usually in the airing cupboard silver or grey body with 2 pipes underneath. you may find 3 pipes if so then you have a diverter valve instead.

a single radiator is insufficient to get the heat away from the boiler and really you need at least 2 without trvs bathroom + another room which should have a room thermostat.

what size pipework comes off the boiler? as these boilers should have a minimum of 1 metre in 28mm on the flow /return to get rid of the heat . many installers undersize the pipes in 22mm