The big switch off

Well it is finally wam enough for me to do the big switch off. Which I did last week turning the controls from heating and water to just hot water.

What I have found is that when the hot water is on the upstairs radiators are coming on as well. My first thought was that it was the three way valve but I ruled this out as the radiators downstairs are remaining cold. Any ideas anyone?

system is an open vented with a new condensing boiler. Four radiators upstairs and four down. The circulating pump is coming on. The system seems to be making more noise than usual as well. You can hear the water going round the pipes.

Apologies if their is not enough info.

Your first thought was almost certainly right, the valve will be not closing completely and allowing a small amount of flow through...not enough to heat all the rads.

Thanks for that have you any idea on an approximate price to get a valve replaced and is it an easy DIY job. I have turned all the radiators off upstairs which is an inerim solution.

One positive leaving the radiator on in the bathoom means I have a heated towel rail. Not all bad!

Chances are turning all your upstairs rads off will force it downstairs. To check the 3 way valve turn off heating and hot water at the clock for a few hours and let them cool completely, then fire up hot water....the pipe should get hot from the valve to the cylinder and the opposite pipe to rads should stay cool (check 12" from valve). If it gets hot then the valve is passing, very occasionally this can be the spring not pulling the valve shut but it is almost always the actual valve itself. Tell us which valve it is and we can tell you the best way to go, fairly simple to swap like for like but it is a wet job.