It's a Worcester Greenstar 30Si, ten years old, regularly and recently serviced. The fault only occurs in very cold weather, like now:
First thing in the morning, the programmer's asking for heat, but the boiler's off. The radiators are cold, or slightly warm. If I run the hot tap, the water initially comes out scalding hot – much hotter than usual. After a minute or two, I turn off the tap, and the boiler fires up and runs normally … until later in the day, when the problem repeats.
What would be causing this?
First thing in the morning, the programmer's asking for heat, but the boiler's off. The radiators are cold, or slightly warm. If I run the hot tap, the water initially comes out scalding hot – much hotter than usual. After a minute or two, I turn off the tap, and the boiler fires up and runs normally … until later in the day, when the problem repeats.
What would be causing this?
