my WB Highflow 400 stopped working today

[JimboStockport]

Hi All,

My combi boiler stopped working today. Woke up this morning with no HW or CH.

I had no work done on the system at all.

I had turned it off and back on as per the manual. But still there is no HW or CH. I felt the top of the boiler and it was hot ... and I also put my hand on the pump and it too was hot. However, all the connecting pipe are cold.

The boiler is a Worcester Bosch Highflow 400 RSF ... I think it is an old one as it only has one switch for HW, OFF and HW&CH ... and two dials for choosing temperature of HW and CH.

Any advice on how to diagnose the problem or get the system back woule be greatly appreciated.

thanks,
Jimbo.

 

[kevplumb]

check the pump is running it will still get hot if stuck

 

[JimboStockport]

I am not sure how to check if the pump is running ...
But I tried listening[putting a screw driver against it and my ear] to it and putting my hand on it ... it seems to be running, i.e. I feel a little vibration.

Could you tell me the best way to check if the pump is running or stuck?

Thanks.

 

[kevplumb]

undo the big screw on the front and you can see the shaft will be a bit of water drips out

 

[JimboStockport]

Yes. undone the screw and I can see and feel the shaft is rotating.

Ok, does that mean I can rule out faulty pump?

Jimbo.

 

[croydoncorgi]

Can you hear any activity inside the boiler when it's supposed to be running? Fan noise, rapid tick-tick-tick from the igniter.

Is it actually lighting, burning for (say) 30 seconds to 2 minutes, then cutting out?

Any warning light (red) lit? flashing? Once per sec? 5 times per sec?

Pressure on gauge?

If it's lighting then cutting out, with pump running, my first guess would be jammed diverter valve.

 

[JimboStockport]

When i turn on the boiler I can hear the clicking sound follows by a humming sound of the boiler, which I presume is the gas burning.

I left it on for about 2 hour this evening. It did NOT cut out at all.
The boiler felt hot and the pump felt hot. However, all the pipes were cold.

There are only 2 lights, the StandBy and the Demand lights. They are both ON. They are not flashing.

Thanks,
Jimbo.

 

[JimboStockport]

Oh by the way, the pressure on the guage is 1.5 bar.

 

[croydoncorgi]

Quiet hum could be just the pump. Louder hum would be flue fan, suggesting its lighting. But if the pipes stay cold (right up close to the boiler - it can't be.

Needs Seeing To!

 

[COG]

If its RSF then you have two overhat stats under the controll box ,the one on the left is for the slave tank (hot water) and the one on the right is for primary temp, if you look from under the dials you should see them . press the center of the button if you feel resistanse push against it and it should click in and on , if that cures it you then need to find out why it tripped (tats the tricky bit)