first thanks to all that have replyed.i have made some enquires into this issue,or debate the way its going,,,,i have spoken to a very clever man called tony bickerton that has worked for vx,for has long as he can remember,and has done some resarch for me,some early v6 omegas,and later carltons,did not have heater bypass valves fitted,and were plumbed directly.mycar being a late 95,cd v6 varient does,and with aircon.and by doing away with so mentioned valve,and,teeing in vacc pipe,is a suitable way,or bodge as some say.of making heaters work.as for issue of other vacc pipe issues,all the vacc pipes seem to be taken fro the main vaccum pipe .i have followed these pipes to various locations aroundthe engine ,and driving 70 odd miles to work,at 4 in the morning, with heat,i con honestly say all is fine,i am not using any more fuel than i normally use,ie 30ish to gallon,car run well, with no lack of power.tony has done thi conversion on a few omegas in the past,1 to the delight of some people,and im gratefull for his info,i do not want to cause,big issues over this.all ive tried to put across is that it has worked,and im more than happy.so once again thanks,so please no nasty remarks