I've recently moved in to a house with a pressurised heating system comprising an Ideal Classic gas boiler and a Megaflo cylinder.
The house was a repossession, and the system was drained down when I first moved in. I re-filled and bled the air out of the rads before starting the system up.
The system works fine for both heating and hot water, but the pressure in the system drops occasionally, and I need to top up the system from the mains (which only takes a few seconds).
The pressure drop is quite slow and/or occasional. Sometimes it will go for a week without changing, but sometimes I find that the pressure has dropped from the normal 1.5 bar down to 0.5 bar or even lower. There are no obvious leaks or strange noises.
My main concern is that there is a leak somewhere that will cause problems over time. However, the fact that the pressure drop doesn't seem constant implies that it's something else to me.
So, any ideas where to start? Is it worth trying something like Fernox leak sealant just in case there's a small leak somewhere? Any downsides to this stuff (apart from the wasted cost if it doesn't work)?
Caecilius