why would you want to do that in the first place put the hearth down first then it doesnt matter about the floor or the fire ( make sure you know where the line is going first
dont think its the above as you would still get the ignitor sounds more like the gas valve/solenoid is out that would account for no spark no gas if no power was getting to it altough i also would be inclined to say the ffd
could be sludge in the rads make sure both valves are open the return and obiously the flow try bleeding the pump aswell just loosen the nut in the middle ever so slightly and be careful the water is very hot
it could be a condensing boiler thats why youre seeing so much fumes there are extensions but depending on the boiler up to a maximum of 6 meteres - 1 metre for every 45 degree bend seek the help of the local gas company btw it wont be cheap to fit an extension
I had something similar it turned out the person who wired it up used 13 amp connector strips as opposed to 45 amp in the attic the wires were melted into each other smoking away i reckon it was about two or three more showers before it burst into flames
