Worcestor 350 boiling dry ?

[edie209]

Hi All first post here.

We have a Worcestor 350 Boiler the one with two pumps. Recently it was cutting out when running hot water too long the button on top (lockout reset button) had to be reset to enable it again, so we had the thermostat replaced along with the Expansion vessel and the pressure relief valve. Everything worked well for a couple of weeks then the relay RL1 started buzzing and we we had to replace the pcb once that was replaced the other pcb developed a fault immediately so we replaced that too.

Now the system starts and ignites but if we don't run hot water it sounds like its boiling dry?? (sounds like a kettle with no water in it) and trips the lockout reset button.

What I need is some advice as to what I should be looking at as I don't want to call out the boiler man again as he charged me nearly £50n just to agree with what I thought initially

 

[picasso]

Why does it ignite when your not running the hot water ? is it just igniting with no demand ?

 

[edie209]

Hi Thanks for the reply.

You know I hadn't thought about that, your right it should only ignite on demand, so that must be the root of the problem. What tells the boiler to ignite and boil the water? could that be the fault?

 

[picasso]

With the information you have given I would have thought the dhw flow switched could be stuck on.

 

[edie209]

Thanks again for the reply, now this is where I start to fail in the knowledge stacks what is the dhw flow switch

I have added a picture of my boiler is it the green connector on the pipe to the to mid left?

Untitled

• edie209
• 3 Aug 2013
• 1

 

[bellairaphon]

Never worked on this model but believe the black object in the picture below the expansion vessel is your dhw flows witch. Have you checked you don't have any dripping hw taps.

Nathan

 

[picasso]

View media item 64602

 

[edie209]

thanks for that both of you. Another question can I remove and clean the switch or do I have to buy a new one and replace.

 

[bellairaphon]

How often does it come on by itself?

 

[edie209]

Everytime since the new pcbs were fitted

 

[bellairaphon]

Is there a link in the heating on the board that hasn't been removed?

 

[edie209]

I'm not quite sure what you mean. Is there something I should have removed from the pcb before I fitted it?

 

[bellairaphon]

If you have a roomstat and or timeclock there will be a link on the pcb that should of been removed.

 

[boabcelt]

Beware that when the ignition board ( small one on the left) is changed, it's possible to plug the dhw pump onto the wrong terminal on the pcb. The ch pump will run on hot water demand, and the dhw pump will run on ch demand. This can cause overheat problems.

 

[edie209]

Hi thanks for your replies, I have spent all day trying to suss out what I have done wrong but I don't think I have, so I have uploaded before and after photos (luckily I always take photos before fore I start something like this) just incase someone can see my glaring mistake.

Before

rh side old

• edie209
• 4 Aug 2013
• 1

After

lh side new

• edie209
• 4 Aug 2013
• 1

Before

rh side old

• edie209
• 4 Aug 2013
• 1

After

rh side new

• edie209
• 4 Aug 2013
• 1