In the absence of any decent football to talk about, and following on from bog, shower and microwave problems on another thread, I thought I'd impart another recent DIY story @ Chez Sparkey that might help someone - this time with my CH system.
Been experiencing pressure drop on my Megaflow sealed system these past few months through the winter. Had to top it up regularly to maintain pressure at about 1 bar. Must be a small leak somewhere so checked all the rad valves, drain offs, boiler and cylinder unions, pipework in backs of cupboards and even looked for any small damp patches on the ceilings to indicate a problem under the bedroom floorboards. Nothing - dry as a bloody bone so my worst fears were probably the case.
My ground floor CH pipes are all laid in the floor screed and I've got engineered oak hardwood laid over the top of it throughout. Knew where the pipe runs were, but had no idea where the small leak might be - it could have been anywhere and didn't fancy ripping that lot up to find it.
Spoke to Fernox a few weeks back about their Polymer Emulsion system leak sealer. It seeks out small weeps and leaks and seals it from the inside permanently, so thought I'd give it a go. Two cans of pressurised Fernox F4 Express whacked into the system through the filling loop (no more than a 5 minute job), fired up the system to full heat and let it run.
Topped up the pressure to exactly 1 bar on the gauge when hot and waited. Let it cool off overnight as usual and fired up to full heat again the next day - the dial hadn't budged. I've checked the gauge every day since and three weeks later it hasn't shifted off that 1 bar marker on the dial - just brilliant.
That stuff is just bloody magic and has probably saved me hundreds if not thousands of pounds ripping up and re-laying my flooring. BTW, I'm not receiving any commission on this post

but if it helps anyone else with a similar problem, it'll have been worth it.