Combi boiler problem

[Happyharry]

Hi this is my first post so please be gentle.
I have a Worcester greenstar 28i junior combi fitted in my house, we were having a troublesome drip from the back right of boiler, we found a gas safe plumber who come round and had a good look, he told me the back right hand block was leaking and needed to be replaced, we accepted and he said he would come back when the part arrives.
So the plumber came and fitted the big part, we paid him and he left.
Our boiler is set to preheat, seems to fire up every 30 minutes, anyway the first day we thought it's very hot in the house, how can this be the heating has been off for months. We checked the heating was set to off and it was. Now we never had this problem before the fitted the new part.
We contacted him and after about a week he came back round to take a look, he took a look at this and that but nothing. Now I had Googled our problem and saw a great video on YouTube of the diverter valve going up and down, I showed the plumber and low and behold the valve goes all the way down but doesn't go completely up.
He turned the valve off to stop rads getting hot and said he would look into this, as the diverter valve all came attached to the new back right hand block.
So could I kindly ask you clever people could it be a faulty or stuck diverter valve and as the valve doesn't go all the way to the top could this what is sending hot water to the rads when the boiler fires up for preheat.
I would appreciate any help solving this, as we paid £400 and the leak is fixed but we have red hot rads when boiler fires up for preheat.
Many thanks

 

[ShaunCorbs]

Did he use the old diverter off the old block as tbh they normally work fine from new

 

[Happyharry]

Did he use the old diverter off the old block as tbh they normally work fine from new

No I think it was the old one.
Anything else that could cause this problem if it's not the diverter valve ?
Thank you

 

[ShaunCorbs]

No I think it was the old one.
Anything else that could cause this problem if it's not the diverter valve ?
Thank you

He replaced something that looked like that ? Correct

 

[Happyharry]

View attachment 94647


He replaced something that looked like that ? Correct

Yes correct, but when he come back to see if he could locate the issue, he took green cover off the diverter valve, the needle/valve went all the way down but did not go right to the top

 

[ShaunCorbs]

Yes correct, but when he come back to see if he could locate the issue, he took green cover off the diverter valve, the needle/valve went all the way down but did not go right to the top

Yes correct, but when he come back to see if he could locate the issue, he took green cover off the diverter valve, the needle/valve went all the way down but did not go right to the top

Everything should be new so should work best speak to the gas engineer who fitted it

 

[Happyharry]

Everything should be new so should work best speak to the gas engineer who fitted it

He has been out and had a look, and said the diverter valve is going all the way down but not getting to the top completely, he then turned a valve to stop the radiators from getting hot when preheat kicks in
Is there anything else that could cause this issue ?
Many thanks for your help

 

[ShaunCorbs]

He has been out and had a look, and said the diverter valve is going all the way down but not getting to the top completely, he then turned a valve to stop the radiators from getting hot when preheat kicks in
Is there anything else that could cause this issue ?
Many thanks for your help

Diverter motor might be faulty or cheap second hand parts tbh never had a problem with new parts other than doa eg dead

Tried the old turn it off and on again

Water spilled on the pcb?

 

[Happyharry]

Diverter motor might be faulty or cheap second hand parts tbh never had a problem with new parts other than doa eg dead

Tried the old turn it off and on again

Water spilled on the pcb?

Neighbour had the exact same boiler installed when the lady who was in my house before me had her boiler fitted.
So been round to neighbours and taken a photo of there diverter valve with no hot water or heating called for, I think by the 2 pictures you can clearly see it is not going right up to the top thus still allowing hot water to escape through the radiators

 

[Happyharry]

Just wanted to post an update.
When the plumber came to replace back block I saw him take it out of new packaging so it was new.
Suppliers couldn't believe the diverter valve could be faulty on a new part, so I recorded a video from them and once they saw it they gave the plumber a brand new diverter unit and he fitted and hey presto everything is working as it should do now.
Happy days 🎉💯👍

 

[Happyharry]

Just when I thought my nightmare was over I have another issue.
Downstairs shower room and kitchen tap red hot water all the time, run a bath upstairs starts coming out red hot and then goes cold then comes back red hot and continues until bath is run.
Any ideas you wonderful people ?

 

[Happyharry]

Would this be caused by airlock ?

 

[Happyharry]

Anybody help me out please ?

 

[ShaunCorbs]

Not an air lock

Does the burner light go out when the bath tap is on?

 

[Happyharry]

The burner light goes out, and noise from boiler like it is trying to fire up but doesn't and also notice pressure gauge needle moving up and down ie 1 to 2
It's also happening on kitchen taps now

 

[Happyharry]

Trying the hot tap now and just getting noise from boiler trying to start up but doesn't and no green ignition light

 

[ShaunCorbs]

Flow pipe hot to the rads eg first one on the left

 

[Happyharry]

Flow pipe hot to the rads eg first one on the left

Tried kitchen tap again fired up and then cut out after minute
6 pipes under boiler 1,2 and 5 hot

 

[ShaunCorbs]

Sounds like you need to call him back as pipes under the boiler 1 and 5 shouldn’t be getting hot when you run the taps

 

[Happyharry]

Sounds like you need to call him back as pipes under the boiler 1 and 5 shouldn’t be getting hot when you run the taps

There is 6 pipes under the boiler and one goes out the wall, the only pipe that actually gets to hot to touch is pipe 2, the 22mm pipe either side of the boiler are cold, I presume they are heating pipes