Hi guys hope you can help. I have a microbore CH system in my house, been having a few problems with a rad or two downstairs not getting as hot as the others in the house. Went through bleeding then balancing all the rads re instructions found on the web. All seemed OK after balancing felt pretty good about fixing this BUT just about to sit down for a cuppa and HW came on timer and noticed all my rads downstairs cooled right off, upstairs still v Hot. Noticed this was happening last week before balancing and I was hoping this may get fixed as well, but seems not. It never used to do this, any suggestions ? I have a valve in the airing cupboard labelled \\\"balance valve to primarys\\\" pipes seem to relate to hw/ch feed, could this need adjusting ?