Balancing a heating system...
I get asked about this surprisingly often. There is much confusion about this
apparently mysterious thing heating engineers do called 'balancing'.
Many people don't realise a radiator has a valve on both
ends (the blank cap at the opposite end of the radiator to the normal on/off
valve also has a valve underneath it), and those who do, sometimes don't realise
it has two completely separate functions...
1) To allow the radiator to be isolated and removed from the heating system
without turning off and draining the whole system.
2) To partially close and restrict the flow of hot water through the
radiators closest to the pump in order to divert it to the more distant
When the lockshield valve (the plumber's name for the valve with the blank
cap) has been adjusted as in 2), the system is said to have been balanced. So
balancing is quite a simple concept really. When a perfectly balanced system is
turned on, all the radiators will warm up equally quickly, rather than some
sooner at the expense of others., but of course there is no such thing as a
perfectly balanced system in real life.
Balancing is actually a very hit-and-miss affair. A quick, rough, intuitive
balance (if any balancing at all) is all that's done when a heating engineer
commissions a new system, and this is usually perfectly adequate. He'll fully
close then open half a turn the lockshield valves on any radiators very close to
the pump, then perhaps half close those a bit further out, and leave fully open
all the more distant radiators. Upstairs radiators usually need to be closed
more than downstairs, to counteract the natural tendency for hot water to rise
and flow to the higher radiators at the expense of radiators below.
It's easy to end up fiddling about for hours balancing a system ever more
accurately, but it really doesn't matter that much. As long as all the radiators
heat up within 15 minutes or so no-one is likely to realise a system is poorly
balanced. In fact the settings are often lost once a few decorators have removed
the radiators to decorate behind, then replaced them and fully opened the
lockshield valves. Users rarely notice!