HW/CH Noise

[Toughie]

We have recently had an unvented cylinder installed (Aug 25) and new system boiler Worcester Bosch Greenstar 4000.

All is working well, but in the early hours of the morning sometimes around 6am we hear what sounds like water rushing or filling up a tank. It lasts between 4-5 seconds and happens once or twice each time. Both the CH and HW are set to off at this time and nobody has been up drawing any water. The sound is loud enough to wake us up but I can’t seem to pinpoint what it is.

I went down to check the boiler which was off and pipes still cold. Checked the programmer which shows both CH and HW off.

We cannot pinpoint what this is but have heard it every morning for the last week.

Any idea what could be causing this before I call a heating engineer?

Any help is appreciated

 

[gas112]

Some boilers have an in built timer on the pcb that starts the pump up for a short period every 24 hours to make sure it doesnt stick
They also have an in built frost that that would kick in if temp drps below 5 degrees but still too warm for that and you would feel heat in the pipes

 

[Toughie]

Hi Gas112

Thank you for the response.

I was aware of this feature but thought it only operated if the boiler hadn’t been used for 24 hours.

We’ve had our CH on every day for last few weeks. Do you think the system isn’t picking this up?