Ideal ICOS HE18 C and flashing burner light

[bengrauwiler]

Hi, I have a fault with an Ideal Icos HE18. It works fine when there is a demand for central heating. When I call for hot water or hot water and central heating simultaneously the boiler displays C and the burner LED blinks constantly. When you first send the demands to boiler it does fire for a short period before defaulting to the blinking LED. The boiler also never returns to standby ‘O’ mode. It always displays a C even when there is no demand from the Hive thermostat. I don’t believe it is a fault with the mid position valve as this has been replaced and required identically to the previous valve. The issue before having been we had hot water but no heating “stuck valve”.

The system is a Y Plan, with pump and mid position valve (Honeywell) located in the airing cupboard within the house, boiler is located in the garage outside. The programmer/thermostat is a dual channel Hive.

I’ve checked the wiring repeatedly and I’m convinced that it is correct. The hive is operating the controls correctly as it should do. You ask it for heating, the pump kicks in, you can hear the syncro on the three port and the boiler fires. Turn it off and it all goes off. Same process for hot water, but the boiler itself just doesn’t want to fire and it does the same when it has a demand for both.

Any help much appreciated. Before any one points it out, I have contacted an experienced gas engineer and he was scratching his head too.

 

[bengrauwiler]

The pump and flow & or return is noisy near the boiler when set to HW only or both CH & HW it is quiet when on CH only, could air trapped in the hot water circuit be causing the boiler to over heat? There are no air vents on the hot water circuit. There is a drain off on the one of the pipes above the boiler, not sure if it’s flow or return, would attaching hose to this and allow the water/air to escape this way cause the system to empty quicker than it can refill? Obviously don’t want to allow the pump to run dry.