no heat in down stair radiators, turned of all rads gradually turned them on starting with down stairs first rad heated great but as all were turned on others became luke warm and now back to just upstairs heating.
Stupidly took of all valve caps to turn of so now unsure which is lv/cv.
any ideas please this is a microbore system
Close all upstair radiators and prove you have heat going to down stair radiators. If you have then open the upstairs radiator lock shield valves, one at a time, slightly untill you can feel heat passing through the pipe (have patience). When you can feel the heat stop and move on to the next rad. The mix up with the rad caps is not important.