Trying to re-pressurise my Sime Super 90 Plus, I opened filling loop valve and let water in to 1 bar pressure. Once the valve was closed the pressure went on rising to around 3 bar. I have tried bleeding a rad, but this doesn't seem to be having any effect at all (have let out at least 5 litres). Could the valve still be letting water through? I understand that the filling loop should not be permanently connected in any case, could someone explain how to disconnect it so I can see if this makes any difference? Or should I just keep bleeding the rad until it goes down?

Also, is it dangerous to run the boiler at this pressure for any length of time?

Sarahlou, May 2007

Most filling loops have an isolation tap coming from the cold water supply pipe below the boiler. Some have a tap head like a normal sink tap other's have a small plastic handle like a washing machine tap. Others just have a screwdriver slot adjuster.
Whichever one you have try moving it to see if you can stop water passing.
Sometimes it only requires a small amount of movement to go from open to closed.
Even a small drip going through becomes pressurised eventually.

T.h.s, May 2007

Thanks T.h.s. - but could you explain how I adjust the valve??

I'm not planning to use the boiler much, just want to be sure I can have showers for the next couple of days without blowing the place up or having to call out an emergency plumber at extortionate bank holiday weekend rates...

Sarahlou, May 2007

If the filling loop is passing water it will be under pressure. You would have to turn off your incoming cold water main and open a cold tap to one of the sinks to take the pressure off the filling loop.
Then disconnect the filling loop from the heating pipe end and get someone to turn the cold main back on. You will see then if it's passing.
If it is you can try adjusting it until it stops. If it won't stop it will need a new one.
If you run it too high the pressure will escape through the relief valve which should be fitted through the wall near the boiler to the outside.
It's not a great idea to run it for long with too much pressure.
Hope this helps.

T.h.s, May 2007