Boiler pressure keeps increasing

[mk85]

-Vailant combi boiler – ecoTEC plus 824
-Boiler is 3 years old.
-The Cold Water-in valve has a flexi hose which is connected to the CH Flow pipe. There are 2 grey knobs on the flexi hose valves which both need to be opened a quarter turn to increase CH boiler pressure.

Last week I noticed the boiler pressure had dropped to 0.6bar. I increased the pressure to 1.2bars while the heating was off, by turning both the grey knobs.

A week later I noticed the pressure had increased to 2.8bars. I bled a radiator so that the pressure reduced to 1.2bars. 2 days later the pressure had increased to 2.5 bars.

(NOTE – Both the knobs on the flexi hose were in the closed position after refilling – and double checked on both occasions.)

Again I bled a radiator to reduce the pressure to 1bar this time. I also disconnected the flexi-hose from the CH Flow pipe end only.

I noticed a small drip from the flexi hose (1 drip every 10 seconds) AND a small drip from the CH Flow valve (1 drip every 3 seconds)

I took the grey knobs off and used a pair of pliers to make sure both the Cold Water-in and CH Flow valves were totally tight in the closed position.

But both drips have continued. What is the likely problem? and what would be the solution?

 

[oldbuffer]

Sounds as if both valves are letting a small amount of water past, even in the closed position. This would account for the rise in pressure before disconnecting the filling loop. Only real solution is to replace both valves. Get good quality ones, not cheap ones. It will require turning the incoming cold water off at your main stopcock and draining down the system (unless you can freeze the boiler flow).

You might wish to consider re-installing the filling loop between the cold inlet and the boiler return pipe, as the return is cooler than the flow, and the valve may last longer. If doing that, don't forget to blank off / remove the old connection to the flow.

 

[MANDATE]

I witnessed a valve a few months back that had been turned off (with filling loop disconected)fully to the stop, it leaked and pressure reducing. Obvious solution was a replacement valve.
Then found by turning clockwise a very small amount the leak stopped and pressure stable

 

[Bunnyman]

A known prob I'm afraid change valve 0020010295

 

[Bunnyman]

Just change the valve an stop fookin about