Ariston/Styx SX 20 - No full burner in heating mode

[Willis West]

I have been called out to an Ariston/Styx SX 20 boiler and the burner is firing full when the DHW is ran but when the central heating is put on from cold start then the burner remains at low level. The radiators are getting a wee bit of heat but nowhere near what they should be. Has anyone came across this before with this boiler?

Thanks

Mark

 

[Billy Bob Bob]

your gas pressures are out or the ch stat is failing or the systems chocked to death or the pumps on its last legs

 

[Willis West]

Thanks for the reply.if the gas pressures were not right then would it not fire in hot water mode as well?i will check the other things u mentioned

 

[Billy Bob Bob]

Thanks for the reply.if the gas pressures were not right then would it not fire in hot water mode as well?i will check the other things u mentioned

check min and max as per mi,s come back if you dont have mi,s