Ideal ICOS Boiler

If boiler shows '0' then everything should be quiet and off :eek: '0' is boiler waiting for command from external heat control. No built in frost stat on this model.

3 port valve head simple to change. All electrical ;)
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Oh and by the way...

- the boiler is in a utility so presumably no frost stat?
- there is a Honeywell valve (replacement head code 4000 3916 - 001 not sure if the original is a V4043 or a V4073?)
- there is also a Drayton Zone valve actuator ZA6
- and a Grundfos 15/50 pump

(none of this means anything to me, I am simply reading part numbers off of the bits and typing them into google to get this info!)

Any help would be hugely appreciated, and might me I can get some sleep and have a hot shower in the morning instead of one or the other!

Thanks gas4you! I think our last two posts crossed. The current noise is coming from the Grundfos pump. I'm guessing that the tank is being filled (my wife just had a bath!).

I can now see that changing either the Honeywell valve or the Drayton valve look to be all electrical jobs :) . Any suggestion which I should try first?

Before posting on this forum, I contacted Ideal technical help desk (basic support) & after explaining the symptoms they were quick to diagnose a fault external to the boiler. They said the voltage input was incorrect?? And advised me to get an electrician (though they didn't fill me with not sure).

I don't suppose you can download the maintenance manual from the web? I haven't dabbled with boilers before, so am a bit weary.

thanks for all suggestions.
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2 port valve heads even simpler to change. You need to have the cover off your wiring centre and test each orange wire off the valves, if one is live regardless of whether there is a call for heat then this will be the faulty one.

Only attempt this if you are confident you can work safely testing live electrics :eek:
Thanks for all the suggestions gas4you. I since played with it a bit more and found that the switch on the Drayton 2 port valve head was in the "a" position (it's an older one with only A and B marked on the switch as opposed to W, M, H). I turned the power off, manually moved the switch to the unmarked mid position and switched the power back on, and hey presto it's fixed! :D

I guess it might still be dodgy, but for now it seems to work.

DominicR, don't know if your problem is the same but it's worth a try before going to any expense and before getting into and work you're not confident of.

I have the following irritating issue with my boiler:

Even with the thermostat set to minium (zero) and the timer off, the boiler springs to life, every 10 minutes or so!! And all through the night.

The boiler heats the radiators & hot water ok but it seems to have a mind of its own.

The first sign of trouble happened when the radiators remained on and wouldn't cool or go off, even though the thermostat and timer were off. An engineer attended and reset the boiler. Now the boiler just seems to come on/off randomly. I have tried pressing the reset button on the front but this didn't seem to do anything, I have also power cycled the unit. The boilers status is "c" and remains flashing "c".

I suspect the timer or thermostat is on the blink??

Any advice greatly appreciated.


I have had the same problem boiler coming on randomly when the outside temp drops . Technician came out and said I would have to put up with it till weather improved. When he had gone I found a stat on the garage wall turned it down and the boiler shut down, does anyone know what the calibration of the stat is, it is a white switch marked from 3 to 10 (3 being the lowest). when it is turned off (below the 3) boiler goes off but I can't find out what these figures relate to in Temperature. Also when it strikes up it makes a horrible whinning noise for about 4 minutes the engineer put a new fan on but said it wouldn't quiten down until they put a new heat exchanger on is this true? Not got too much confidence in him if he didn't know it had got a frost protection stat on it.

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