Hi, I need to replace a 3 port valve that's sticking on my Y plan system. Pump has isolation valves and 3 port valve is above all radiators with the exception of one towel radiator (pipework to rads goes down from valve). Would I be able to isolate the valve (and towel radiator) and replace the 3 port valve without draining the system? With the pump isolated I wouldn't have thought much water could run uphill to the 3 port valve could it? I assume the heating coil inside the HW cylinder is sealed and isn't vented. Thanks
No not pressurised as far as I know. Fed by the header tanks so presumably if pump is isolated Sorry should've said it's a vented system so no, not pressurised.
Easy job, bung the F&E cold feed and open vent, Crack a nut on the three port and catch the water in a bowl. Have a bucket and old towel to hand. You will get about a pint to a pint and a half of water before it locks up. You can now comfortably remove the valve. Needless to say the system should be idle, you will need to isolate it at the fused spur anyway to re wire the actuator. Normally takes about half an hour. http://www.ebay.co.uk/sch/sis.html?_nkw=Radiator+Valve+Change+Kit+Bung+Kit+REGIN+REGR05
Thanks Dave. I think that makes sense but if the F&E is connected before pump wouldn't isolating the pump lock it off?
No because you have the open vent as well as the cold feed on the F&E tank so you will alwas have an open end. If you bung both then the water will lock up and you can do what you like.