Arrived on site to continue diagnosing intermittent no hot water. After speaking with tech support for the 2nd time they believe the flow sensor has failed but they could not really give any concrete reasons for the issue we are experiencing. The boiler circulator pump seems to be not working intermittently but when the boiler is reset it’ll start working again. We have a flow sensor ordered and should be available for pickup tomorrow morning. We will be in touch to get it scheduled. Thank you for your patience.