Glow worm micron 50FF switches on when it shouldn't

[dt99idr]

Moved into a new house with a Micron 50FF boiler.

Have noticed that every so often the boiler switches on for a few seconds. It does this when the programmer is showing off for both hotwater and heating demand.

The boiler appears to work fine in all other regards.

I'm not sure exactly how often it does this but the boiler never seems to be 'cold'.

Anyone else seen this issue? I'm wondering if it is the frost protection kicking in at the wrong temp but not sure how to prove this?

Thanks,

Ian

 

[Tibbot]

It has no in-built frost protection. Check zone valves are not faulty, passing live to boiler SL.

 

[dt99idr]

Thanks Tibbot,
I think you've set me on the right track. I believe I have a wiring fault. (goodness knows why the previous owners never picked up on it!)

From my reading of the 50FF Installation guide the boiler is a simple on/off affair with its mains power being switched on/off my by controller. i.e. if the controller is switched 'off' for both DHW and HTG the boiler should be un-powered and I shouldn't be able to get it to do anything with the LEDs.

If this is correct, it looks like the boiler is permanently powered (and I think the pump is too) so the boiler is continually lighting every few mins to keep the water in the By-pass hot.

If Tibbot or someone else can confirm I'm not being a complete muppet regarding the simple on/off nature of the micron 50FF I'd be very grateful.

Many thanks,

Ian

 

[swbjackson]

You're correct so there must be a fault in the wiring or controls somewhere. Time to get busy with the multimeter.

 

[45yearsagasman]

It will almost 100% be a zone valve fault as suggested earlier. What zone valves do you have?

 

[dt99idr]

zone valves are a honeywell for the DHW and a Danfoss for the HTG.
if I manually switch these to open I can hear the waterflow change (and in the case of the HTG the radiators get hot). So I think the valves are OK.

Can you manually switch the valves to off or just on?

Thanks,

Ian

 

[Tibbot]

No, it does not mean they're ok. That's not how you test zone valves for your particular fault. As suggested earlier, you'll need a multimeter.

 

[dt99idr]

Thanks guys, strongly looks like the head of my honeywell valve has gone.

Off to get a new one.

Thanks,

Ian

 

[dt99idr]

Thanks again.

The microswitch in the valve was jammed. With a few clicks it fixed its self.

Probably on it's way out, but I'll know what the problem is if it occurs again.

Thanks for all your help in sorting this one out.

Ian