Ok, I know what its about, how it works, what usually goes wrong, how much they cost and how to fix it, however, I'm stumped with the problem I'm having. Y-plan system, had a new Potterton boiler fitted 12 months ago, new control panel, new valves on all the rads and a new 3-way motorised valve, worked perfectly for 12 months luvvly jubbly, then 2 weeks ago noticed radiators getting hot when calling for hot water, ahhh it'll be the 3-way valve I thought, but no its working as it should, closes for HW, resistance felt when moving the manual overide lever, moves all the way when calling for CH and sits halfway when calling for CH & HW. So I removed the motor and checked the valve using mole grips on the nib, it moves left and right no probs, ok then I thought so using a couple of elastic bands on the mole grips to keep the tension on and thereby closing PortB ( CH) I fired up the heating, sure enough as the hot water was pushed through the valve both A+B outlets on the valve got hot together with no discernible difference in temperature! Could the rubber ball inside have disintegrated in 12 months or come loose or could it be a problem in the boiler I know theres a thing called drain back from the tank but as I have said both outlets get hot immediately ?
Hi Check it the wiring center, you will easily identify the 5 wires from the diverted valve. orange only live = h/w, no valve action, grey and white next the check 240v on grey = call for heating is satisfied ,, so.. 240v on white drives valve to mid position, with power on grey ( hot water satisfied) = valve fully open to c/h With no power on grey (calling for h/w) = valve to mid position, Hope that clear, If it’s different, check out the programmer or stats,