Hi Im trying to replace a sundial y plan 3 position diverter valve but im a bit confused as i thought for a y plan you had to have a mid position valve. Ive bought a drayton 3 port diverter valve, will this do the same thing? The honeywell sundial valve is 3 wired so its def not a mid position valve. Im just confused by the fact it says y plan? can anyone clear this up for me? Thanks
your correct a y plan uses a 3 port mid position valve. Looks like you have a W plan 3 port priority valve honeywell code v40444c. The valve is in hot water position when not powered and moves to central heating when powered. They were used in budget systems to reduce the size of boiler because it only had to heat water or central heating not both at the same time.The big disadvantage was if you ran a bath the system would give priority to reheating the water and the radiators would cool down