Heating only works with hot water

[Gtrust]

Hi, I have an Icos ideal boiler that I'm having problems with. I cannot get the boiler to fire for central heating. The clock is set to continuous heat and the rf thermostat is turned up (the rf unit acknowledges, I hear an audible click and then the valve on the CH system opens but boiler doesn't fire).

The boiler displays the O with no fault codes when I'm calling for central heating. However the CH does work when rf and clock are set to on and the hot water fires. I can force it to do this by running the tap as I have that set to continuous, but as soon as its reheated the water in the tanks it shuts off again.

It seems to me that the rf is functioning as the valve opens, the clock is functioning otherwise it wouldn't allow the rf to open the valve, and the boiler is operating normally for hot water. I have no idea what could be wrong?

 

[gas112]

Valve not opening far enough to activate the microswitch inside

 

[Gtrust]

Thanks, the lever on the side seems to move the full distance and the heating works fine when the hit water is on suggesting there is no restricted flow.

 

[gas112]

yep its not hitting microswitch to give power to boiler

 

[MANDATE]

If it's a 3 port mid position valve its either not going beyond mid point due to faulty micro switch no 1 or if it is going to the CH position then micro switch no 2 will be most likely at fault. It's this switch no 2 that allows power out of the valves orange wire to fire boiler.
I would suggest changing the whole actuator head.

 

[Gtrust]

Untitled

• Gtrust
• 12 Mar 2013
• 1

This is what I have. I assume the system needs draining down to change that, probably a bit beyond my DIY skills.

I am hearing a click when the valve has finished shutting or opening, does that still suggest the micro controller isn't working?

 

[Gtrust]

I can see and hear that the micro switch is being fully depressed. I've also done it manually but still no heating. Next step is wiring to the boiler. How do I bridge it to make it think I'm calling for heat just to make sure it's not that wiring.

 

[bolshy]

You need a voltage tester or multimeter, not a wiring link......

 

[Gtrust]

I'm going to pick one up today but I need a temporary fix regardless. Is it possibel to wire the boiler direct to power so its just on constantly?

 

[Gtrust]

I'm going to replace the micro switch, do you know what I need? is it this

http://www.maplin.co.uk/low-cost-standard-microswitches-6453

 

[MANDATE]

micro switches come in various shapes, sizes and types.
When I stripped down a actuator head due to the same problem, I found the two micro switches side by side and they were the soldered in type terminals.
Not bolt on type that I expected.
Much easier to change the head.
I did manage to remove the side of the problem switch to get to the dirty contacts which were cleaned and re assembled, but of course I had already re placed the head.

 

[Gtrust]

Problem solved. The multimeter revealed no power to the micro switch, the 'expert' I had in at the weekend may have inadvertently wired the switch neutral neutral. I connected grey to a permanent live and all is well again.

Thanks for the help and suggestions. It was indeed the micro switch but a wiring fault rather than faulty switch.

 

[MANDATE]

Just to let you know the 'grey' wire of the valve should be fed from 2 sources
non of which are permanent live.
When HW is satisfied the path to the boiler through the cylinder stat is broken.
The stat is like a two way switch, so it now diverts the power to the 'grey' wire which is required to move the valve forward from mid position.
Of course if HW is not switched on the cylinder stat cannot play an active role and the 'grey' wire could not be made 'live'.
To overcome this the HW switch on the programmer is also a two way switch.
When HW is off, the switch is toggled across and a wire is taken from the HW OFF terminal to join the grey wire of the valve.
If the 'grey' was permanently live, the valve could not be held in the mid position. The grey would just take over from the white when micro switch no 1 is triggered.
For mid position the grey must not be live.

 

[gas112]

Looks like a 2 port in picture not a 3 port mandate

 

[MANDATE]

Looks like a 2 port in picture not a 3 port mandate

Yes! I do agree. I'll make an appointment at SPECSAVERS