combi fires up - without demand

[Ted808]

Went to a main combi, not serviced or looked at for years- can't be that old 5-7yr but shoddy install. Expv flat as per. Got the beast going but it fired once or twice without demand. Dirt in the system right? Sticking flow switch or ....?
any thoughts?

 

[ShaunCorbs]

Isolate cold water does it still fire ?

 

[aggis]

Check the gland on Dhw flow switch, if leaking it can possibly short out the micro switch, making the boiler fire until stat cuts it off.

 

[AMGasServices]

Does the heating work ?

 

[townfanjon]

Storage combi ???

 

[Ted808]

thanks for all the replies- haven't had a call back so it looks like it sorted itself out....I'll store away these nuggets of information.
Thanks again.