boiler pressure

[bc123456bc]

Since we moved into our new house 6 month ago we have had a problem with the boiler loosing pressure. It had to be topped up every couple of weeks. The pressure would drop off to under .5 bar and we would top it up to 2 bar and immediatly would drop down to 1 bar and run at that for a couple of weeks until the next top up.
With the recent hot weather the heating wasn't used for 2 weeks and when it was used after this break the pressure gauge began rising and was up to 4 bar within 10 mins!! I thought the release valve should blow off at about 3 bar but there is nothing coming out the overflow pipe. The heating is now off until its sorted. Any ideas ??
Thanks.
Bob

 

[SortedPlumbing]

Wot kind of boiler you have?

Are you sure it aint letting some water out of blow off pipe outside?

Possible faults
is that your expansion vessel needs recharged,

you may a have a small leak in your CH system somewhere also,

and if your pressure gauge is reading 4 and not letting water outside then that too could also be faulty.