Very hard to get a grub screw out when the internal hex has rounded what I do is I use an outit a left handed screw remover which I cut off the lead on and tap it in then sharply turn anti clockwise it grabs the I remove the grub screw and replace it. Bob
To be honest I’ve seen all sorts of devices each with its own merits but the weirdest one was 4 old telly magnets sawn in half strapped over the main incoming pipe and believe it or not no scale anywhere in the boiler or system. Bob
No insulation needed unless it gets really cold then the fuel can go waxy.
the round thing is a fire valve the button is for resetting. the wire is a capillary tube for wax to expand in the event of a fire. Bob
Get an electric soldering iron and hold it onto the sleeve of the handle for a little while then try to pull it off but use gloves as it will be hot I’ve done this on stiff handles so as not to cause discolouration on the chrome plating when reassembling use silicon grease to get it off next...
I wouldn’t use a carbon tap too brittle always use high speed steel the plug tap is the one to use as it’s straight through and will do a decent job I carry several sets of taps and have found I use them more and more as standards of production have unfortunately fallen in the last few years. Bob
It’s an air addmitence valve it lets the soil pipe breathe you could make it longer and take it through the roof that would get rid of the problem. Bob