We have a Vaillant Combi boiler which has been perfect since it was installed around 5 years ago. Recently the tenant has told us that he wasn’t getting hot water (central heating is OK). The pressure was also very high. The engineer found the expansion vessel was full and the pressure relief valve hadn’t kicked in so both have been changed. The tenant is still not getting hot water unless the flame (reset button) is pressed. He has informed me that he is getting the error code F62. The pressure is not steady at between 1.5 and 1.9 bars although we have disconnected the inlet to check whether the heat exchanger was leaking. Would be grateful for your diagnosis please. Many thanks.
This really depends on the particular boiler model you own. For the Home Combi Boilers, Ecotec Plus and Ecotec Pro series the F.62 fault code refers to a fault with the Gas valve switch-off control. This occurs when the Gas valve does not switch off by its controller when it is supposed to. Meaning that the electronics controller (PCB) is defective. It may also mean that the gas valve may be leaking. This is a serious condition and I would recommend you get a qualified boiler engineer in to fix the issue.