Find a Leak.

[ffsday]

My boiler, Worcester GreenStream 40CDi condensing combi, needs topping regularly, I'm told I have a leak, but where is the leak? One of three possibilities? In the cental heating loop? In the hot water piping? Within the boiler cabinet? If I isolate the ch loop by closing the valves at the base of the boiler and monitor the pressure gauge will that tell me if the ch loop is the problem?. Ditto for the hot water supply? Is it possible for components or piping within the boiler cabinet to be the cause of the pressure loss?
General question: Is it possible to isolate the ch system and still get hot water? And vise vesa?
I live in a top floor flat with others below me. I've been in the loft and can find no signs of water. I've had no complaints of leaks, damp patches or dripping water, from neighbours. I've checked all visible piping and rads. And I've put a balloon over the PVR pipe, nothing.
How does one find a leak? Pay Leakbusters £650?

 

[adlplumbing]

check all rad nuts with dry finger and see if has leak on that point and bled your rads as well

 

[wiss]

If you are loosing pressure its not the hot water exchanger as this would increase pressure, prv letting by???? check to see if discharge pipe is wet outside, if you are sure there are no leaks on the system then it must be the boiler. you can run the boiler for dhw with the heating circuit isolated providing the prv and pv are within the boiler which they should be and not advisable to switch on ch with the circuit isolated (unless boiler has bypass)

 

[macfudd]

Have you tried tightening all exposed compression joints slightly,it doesn`t need to be a very big leak to lose the pressure in a system,be careful if you do it yourself and use 2 spanners,1 to tighten and 1 to hold against.
It`s possible,just possible there is a pinhole in the diaphragm in the expansion vessel.I came across this once before and after I had exhausted all other possibilities I fitted a new expansion vessel and it did the trick.

I suggest you get a good plumber/heating engineer in to have a look.