If its on 0 bar then you have lost pressure for some reason i.e. leak or faulty pressure relief valve or maybe even a pressure gauge fault. Try repressurizing system using filling loop(with c/heating off) fill to 1.5 bar then go round and bleed air out of top of radiators then go back and fill again to 1.5 bar and so on until all the air is out. Check your pressure relief pipe if water is coming out then you need a new pressure relief valve (the pipe is on the xternal wall other side of boiler).
daz71, November 2008
