Biasi M96.28SM/B dhw lock out All aspects of plumbing questions and answers, help, tips and information

[Techno]

With the CH on there is hot water, with the CH off DHW is cold and the Lockout red light comes on. The gas does not ignite. The problem is that it is an intermittent fault sometimes there is DHW sometimes not. But always there if the CH is on. Thanks