Hot water diverting back to the boiler

[finnigan82]

When I put the central heating on the hot water gets drawn through the pump but is then being diverted straight back to the boiler instead of the rads

What is this, and how likely is it that it is faulty?



That sits in between the hot water to the rads and hot water to the hot water tank, then connects to the boiler return pipe

Here's the whole picture:

 

[finnigan82]

 

[finnigan82]

Found out what it is! It's an auto bypass valve, and it's doing it's job

There's a blockage somewhere along the central heating so it's backing up the pressure and causing that bypass valve to open.

Now to find the blockage. Would a powerflush blast that out?

 

[oz-plumber]

Have you considered a faulty by-pass valve or seeing if you can adjust the by-pass valve?
I would replace the by-pass valve prior to spending money on a powerflush.
The by-pass valves is only a spring compressing a washer, adjusted by screwing the handle.
Worth taking a punt on replacing the valve first