Vokera Excel Boiler Problem

[Wasp]

Hi All,

I have an old Vokera Excel boiler which was working fine until about a week ago.

Now, if the boiler is switched 'on' but is not providing central heating or hot water eg. in standby, it makes a banging/scraping/shuddering noise.

When you switch the central heating on (on the boiler) or run a hot water tap or the shower, the noise stops and the boiler quite happily produces hot water.

The noise also stops when the boiler is switched off (as it is now).

I don't do DIY but I'm suspecting this might be something to do with water pressure? Help!

Wasp

NB: Pressure is currently at 2.5 bar on the guage.

 

[twgas]

Hi All,

Now, if the boiler is switched 'on' but is not providing central heating or hot water eg. in standby, it makes a banging/scraping/shuddering noise.

When you switch the central heating on (on the boiler) or run a hot water tap or the shower, the noise stops and the boiler quite happily produces hot water.

The noise also stops when the boiler is switched off (as it is now).

What exactly do you switch off for this, is it the fused spur?

 

[Wasp]

Umm, I 'm not sure what a fused spur is?

(checks wiki)

Oh, no, it dosen't have a socket on the wall as such, we switch it off on the boiler control panel on the boiler?

It has a circular rotating switch/tab which has '0', a sun symbol, then a radiator symbol.

I've just been looking at http://www.vokera.co.uk/trade-professionals/manuals-literature/. It's one of the Excels under 'Discontinued'. Not sure which one!

 

[twgas]

Does it make the noise when control set to summer (the sun)?

 

[Wasp]

Does it make the noise when control set to summer (the sun)?

Yes, it does (just tried it now).

Thanks.

 

[twgas]

Does the boiler light up occasionally when in standby mode? Try turning the selector to "0" and running a hot tap for a couple of minutes, then turn tap off and boiler to summer and observe boiler.

 

[Wasp]

Hi Mick,

Thanks for your time this morning! No, the boiler dosen't light up. The boiler is 'off' when at '0', it dosen't produce any hot water nor does it have any activity. The other two modes are 'on' so to speak, and produce hot water and sadly these new noises.

Wasp

 

[twgas]

I think you misunderstood what I was trying to ask.
When the boiler is set to "sun" does it fire occasionally?
The

Try turning the selector to "0" and running a hot tap for a couple of minutes, then turn tap off and boiler to summer and observe boiler.

bit was to cool the boiler down, then turn it on "sun" and sees if it fires.

 

[Wasp]

Sorry, yes, did what you said, it does fire on 'Summer'. Right now, this morning, no noticeable difference in the modes, both cause the boiler to fire up immediately. We don't use the 'summer' mode tbh.

 

[twgas]

Then I would say the HW flow sensing bits are seized in the on position (the boiler thinks the tap is running)

 

[nickso]

it will be the dhw microswitch. 10 minute job with the case off.