Issue with automatic bypass?

[CountryFan]

I've had a look through some pages relating to automatic bypass valves, but a lot of them cover installing one and overheating, so mine might be a different issue.

I understand what the valve is for, however I'm wondering if it's stuck open? When I have the heating on or dhw the outlet pipe from the abv is red hot to touch, now I know this shouldn't be the case.

My hot water also seems quite hot to touch, so if this abv is broken, could it also send the pump overrun water back through the return of the cylinder?

Thanks

 

[Johntheo5]

It should only send water back via the cylinder to the boiler on pump overrun or very low flowrates if rad TRVs start throttling down.
What make is the ABV and what is its indexed setting at?

 

[CountryFan]

No idea on make, couldn't see one. It has a thin red cap, everything else was Myson, so maybe Myson? I think it's 0.2 the reading.

 

[Johntheo5]

Turn the red cap slowly clockwise to setting 0.25/0.3, see if the pipe cools down with system running normally and gets hot on pump over run if not just make very small adjustments until it does.

 

[CountryFan]

Ok, I'll try this when I get home, thanks

 

[CountryFan]

Just done an internet search and found this which looks similar or the same as mine

 

[CountryFan]

Turn the red cap slowly clockwise to setting 0.25/0.3, see if the pipe cools down with system running normally and gets hot on pump over run if not just make very small adjustments until it does.

Ok, so I follow your advice, however turning this doesn’t do anything other than make a slight ripple in the plastic housing, possibly from the white bit. So, I’m guessing it’s goosed or maybe that cap is only a cover? I can see a screw through the slit.

 

[Johntheo5]

You should feel a nice bit of resistace when making adjustments, it might also take a lot ot turns.

 

[CountryFan]

You should feel a nice bit of resistace when making adjustments, it might also take a lot ot turns.

Hi, so I went to adjust this several times and the cap came off in my hand to reveal a screw and what looks like a spring? Should I adjust this screw? Thanks

 

[Johntheo5]

Havn't a clue, post a photo.

 

[CountryFan]

Thanks. Will have to be later when I'm home from work.

 

[CountryFan]

Havn't a clue, post a photo.

I've just had a look and it's also similar to an Altecnic/Eres automatic bypass, which states to remove the cap to adjust, so I might try this.