My Vaillant Turbomax boiler is only responding to the call for instant domestic hot water, the heating is not working. The error code S.30 is being displayed, I have changed the room thermostat and still no joy, what else could it be?

Andy Davies, July 2007

Did the original poster ever find a solution? Our Vaillant gives S.30 (no demand) in the evenings, although the thermostat seems fine (green light comes on, boiler does not respond). It previously worked fine for a year with no wiring changes. I suspect a logic circuit and/or a sensor input we cannot see. Thanks, J.

J Hinton, February 2009

have you also got your timer set to call for heating? and is the room stat set high enough

gary.wright53@googlemail.com, August 2007

s30 is no call from external heating control

that tells me your room stat is faulty or wired wrong.

hi-spec plumbing, July 2007