Customer complains of Intermittent heating on Y plan with Stat satisfied.
New boiler fitted last year (no permanent live required or fitted previously) on an existing Y plan system. Existing timer was a Randall 103 (no hot water off position as its a timer not a programmer). The customer wanted a digital replacement so I fitted a digital timer (only one switch live out feeding cyl stat and room stat and no H/W off connection) so I couldn't fit a programmer without significant disruption and additional wiring which the customer didn't want. All seemed well, then a few months later he asked me to fit a digital stat Honeywell (DT90E) in place of the old mechanical stat. I think their was an additional wire connected to the stat which didn't appear to be needed on the new one, so I isolated it just in case. Is it possible that the original wiring took the heating satisfied connection as a hot water off live feed?
I have been studying wiring diagrams I don't see how this fault is occurring. If the room stat is satisfied there is no power to the white and the 3 port valve should be in the H/W only position requiring power from the cyl stat to power the pump and boiler. If there is power to the grey and white. It should close off the H/W, but once the room stat is satisfied, the power on the white would stop and the valve should spring return shouldn't it?
Any help or advice would be much appreciated.
Thanks in advance.
New boiler fitted last year (no permanent live required or fitted previously) on an existing Y plan system. Existing timer was a Randall 103 (no hot water off position as its a timer not a programmer). The customer wanted a digital replacement so I fitted a digital timer (only one switch live out feeding cyl stat and room stat and no H/W off connection) so I couldn't fit a programmer without significant disruption and additional wiring which the customer didn't want. All seemed well, then a few months later he asked me to fit a digital stat Honeywell (DT90E) in place of the old mechanical stat. I think their was an additional wire connected to the stat which didn't appear to be needed on the new one, so I isolated it just in case. Is it possible that the original wiring took the heating satisfied connection as a hot water off live feed?
I have been studying wiring diagrams I don't see how this fault is occurring. If the room stat is satisfied there is no power to the white and the 3 port valve should be in the H/W only position requiring power from the cyl stat to power the pump and boiler. If there is power to the grey and white. It should close off the H/W, but once the room stat is satisfied, the power on the white would stop and the valve should spring return shouldn't it?
Any help or advice would be much appreciated.
Thanks in advance.
