I get this as my current house has sloping ceiling in the upstairs rooms but the loft is ridiculously small because of it.
I had to have a boiler replaced in a B2L flat Dec 2016, the plumber was horrified when I said I'd remove the redundant cylinder and a few bits of pipe which amounted to about 4metres, allegedly he had already allowed for £50 scrap in the quote. When I took some other stuff for scrap I asked about cylinders several months and they said around £50 depending on what it is. The value of iron and steel is almost nothing, £2 for a dishwasher but swapped it for a 1/2metre length of RSJ instead to make some brackets. Some places won't take storage heaters if they are the 'brick' type as the cost of losing the disintegrating concrete outweighs the scrap metal value. I have now learnt the importance of separating different metals, armoured cable is worth a lot more if the steel armour is presented pre stripped. I took 3cwt of cast iron soil pipe and fittings, the only reason they allowed me to leave it there was for the lead used to seal the joints.
I should have said something really or asked what they were going to give me before they actually started taking it so it's my own fault, I was even told there should be at least £40 in the cylinder beforehand.
Still I was glad to be rid of it all anyway. If only there was money in cast iron, the whole house currently has it for all the guttering/downpipe which I will be replacing eventually.
It's definitely useful to know that separating the metals beforehand is a good method, that said I won't be taking on another house renovation anytime soon to benefit haha.