How does a Y Plan Central Heating 3 Port Mid Position Motorised Valve work?

2 November 2011

Find Mid Position Valves on EBAY… This interesting article is from DIYFAQ.ORG.UK with links to WIKI for further info. It shows a circuit diagram and explains the internal workings of the 3 Port Mid Position Central Heating Valve commonly used in Honeywell Sundial Y Plan (4073A) and similar Drayton Biflow systems. There’s also some useful info on faulty and stiff […]

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