do you mean the boiler cutout is operating, or what? ......I don't know what that means, It flashes red I then have to reset it
you might need to turn the pump speed up ....it is always at no3 (highest)
have you looked inside the pump, and is it clogged or worn? ..... no, i'm wary of stripping the pump down ic case I can't put it back togethor again (is it easy to do (it looks like this one
http://www.screwfix.com/p/wilo-4132507-smart-central-heating-pump-a-rated/53435 )
Have you bled all the rads, and the pump, with the pump not running? ..... Do you mean loosen the big brass screw on the front of the pump,Yes, that is what I do first, I then fire up the sytem and bleed again to get more air out
Has the circulating water gone black with loosened sludge? ..... it DID look dirtier and it I think it had bits in it (which I assumed was good), but I don't know how "thick" sludge is.
Are the flow pipe and the return pipe on the boiler both too hot to hold? What about the flow and return pipes on all the rads? ......yes
chemicals can be usually be run cold, but take longer. Have a look at the manufacturers website. ......... How do you get the pump to circulate, but the boiler not to fire up...........or do you just turn the boiler down very low
X800 is much faster than X400 and usually works in hours, not weeks.......I wrongly assumed the longer I left it in the better...sorry