Pressure increasing in CH loop

[RichD1]

I've just noticed that the pressure gauge on my Vaillant combi is almost into the red sector!!

I normally run it so that it is the lower 1/4 of the gauge and I have not touched it or filled us the fill loop for over a year now.

I've just drained off about 3/4 litre thro' a bleed valve and that has reduced it down to about half way.

What would cause the pressure in the CH loop to increase?

I've got no expansion vessels fitted apart from what is in the boiler.

Richard

 

[23vc]

Filling loop not shutting off properly, is it an external one outside the boiler? if so probably easier to fix.

 

[RichD1]

I've actually got two. One from the previous boiler when they didn't come as standard and one in the Vaillant.

I'll check them out for closure. Thanks.

Richard

 

[Aquaheat]

@RichD1 Any joy with the filling loops? It would be very strange that the loop has developed a leak if it has not been used unless it has been knocked.

If you disconnect the loop/s then you can be 100% sure.

If this is all good then you will most likely be looking at a pin holed DHW plate heat exchanger. This can occur over time and is usually due to water quality. You can check this by isolating the mains cold water going into the boiler. If this stops the pressure rise then it points to this fault.

Jon

 

[petit_pablo]

Deleted - im all confused lol

 

[oilboffin]

Take off the loops and if the pressure still goes up plate heat exchanger could have gone.Bob

 

[Aquaheat]

Take off the loops and if the pressure still goes up plate heat exchanger could have gone.Bob

Thats what he said ^^^^^^

Jon

 

[RichD1]

All loop taps appear to be fully off. Gauge has not risen since I bled the rad to remove some water. Will keep an eye on it over the next few days to see if it increases again.

Thanks for all the help Guys.

Richard