Pressure problems

Please help me, I have a Glow-Worm 30ci boiler - it is 2 years old, for a year or so the pressure has dropped whenever the boiler is off it doesn\\\'t take very long, i put the pressure to 1 bar - start it up and have to bleed the radiator several times until the boiler holds its own because the pressure rises, when that is done everything is fine throughout the day.The overflow is not dripping.Just recently when the hot water tap is on for a little time the pressure drops again.have read the articles and still not sure what to do, please help me I cannot afford a plumber at the moment.

I have the same problem. I also have a Glow-worm 30ci and my bolier is also 2 years old and it's constantly losing pressure when I open the hot water.

I have a 30si (Heating only) the problem of system pressure dropping slowly is probably due to the PRV (Pressure relief valve) this is designed to release pressure should it rise above 3 bar however they seem to be , I have had 1 unit give up within the warranty period and this was replaced under guarantee (also 2 pumps), the replacement went up the creek about a month ago, I phoned Glow-worm and asked how much it would cost to have a service call, as I do not have a service plan, and as far as I'm concerned 2 years is as new and shouldn't be going wrong!! The lady told me £195 but that would cover all parts. Well I should hope so to, needless to say I didn't take her up on her offer, and took myself off to my local boiler part specialist, got one but that lasted 10 days, (they replaced it F.O.C, but was told that they were selling no end of them, and it appears there is a problem with them and they are lasting between 1-2 years (our boilers were the latest new models of 2 year ago)
The PRV is simple to fit, turn the boiler off and isolate the system pipes, all valves below the boiler, I don't know how many there are if you have hot water, but I have 2, red handled ones one each side, Yellow gas in the middle. Remove the boiler front panel and drop down the control panel, the PRV is just behind on the left, connected to a 15mm drain pipe which is where all your water is going, so to be sure if you can put a container under it you will see it. The PRV is secured by a clip but before removing it depressurize the boiler using the black lever on the front of it, remove the pipe, mind the fibre washer, undo the clip and the remove the valve, water will come out from within the boiler, so have a bucket to hand.
Reversal is obvious, refill the system with 1 bar of pressure all should then be ok again, the only other thing it might be is the expansion tank that is accessible from above the boiler, it has a car/bicycle valve on it and should be pressurized to 0.5 bar with the boiler open to the air, so if you want to check it, do so while the PRV is out.
The PRV part number is S1006700 officially known as a Heating Safety valve 3B and it cost me a breath-taking £13.89.
Hope this is helpful