New boiler setup - hot and cold water cycles repeatedly

[JT_Singh]

Hello - I recently got a new Worcester Greenstar 30i 30kW Combi Boiler 7733600005 installed in my property. Previously I had a 37KW combi boiler but that was 10 years old. But my plumber said that 30KW combi boiler should be more than enoguh.

The day this was installed, I also had my water supply pipe changed from 15mm to 25mm PE to increase the water flow.

Since the day these two things were done, my hot water cycles continuously between extremely hot and freezing cold in all the tap mixers. I am not sure what's gone wrong as the plumber who fixed it confirms that this has nothing to do with the boiler.
Any pointes / advise based on your experience will help.

 

[king of pipes]

Your boiler has a manufacturers warranty providing it has been installed correctly and registered with Worcester and Gas Safe then I would advise a service call from Worcester

 

[Scott_D]

Any pictures of the boiler and pipes underneath?
Have you got any taps that are not mixer taps?

 

[JT_Singh]

Any pictures of the boiler and pipes underneath?
Have you got any taps that are not mixer taps?

I have one tap which is just cold water next to the main supply pipe. This new boiler is being done as a part of the ongoing house extension. So currently everything is in progress. Have attached a few pics for you to have a look.

 

[Scott_D]

Sounds like either hot and cold water are mixing somewhere or there could be a fault with the boiler.
Best to get the installer back.

 

[oz-plumber]

There is either a cross connection between the hot and cold water - it could be a mixer or...

It could be a boiler fault, - temperature sensor, incorrect commissioning, faulty boiler thermostat.
There seems to be a bit of gunk in the condensate trap - for a new boiler this seems odd,

You need the problem fixed, either call installer back or get the manufacturer to send out repair personell

 

[Paul.S]

Hello - I recently got a new Worcester Greenstar 30i 30kW Combi Boiler 7733600005 installed in my property. Previously I had a 37KW combi boiler but that was 10 years old. But my plumber said that 30KW combi boiler should be more than enoguh.

The day this was installed, I also had my water supply pipe changed from 15mm to 25mm PE to increase the water flow.

Since the day these two things were done, my hot water cycles continuously between extremely hot and freezing cold in all the tap mixers. I am not sure what's gone wrong as the plumber who fixed it confirms that this has nothing to do with the boiler.
Any pointes / advise based on your experience will help.

Fit non return valves on mixer feeds