In an earlier contribution to this discussion,
Oldskoolskater wrote:

Hi all

Having looked at the FAQ for answers I have become confused and would
like clarification on the above matter.
Some rads are hot - Do I close up the lockshield valve more on these
rads?

Yes, but see below.

Some rads are warm - Do I open up the lockshield valve more on these
rads?

Ditto.

When the system is properly balanced, you should have more or less the same
temperature drop across each rad. Ideally, you need to measure the
temperature of the flow and return pipe on each rad - for which an IR
non-contact thermometer makes life a lot easier - and progressively close
the lockshields on the rads with the lowest differential (i.e. the hottest
rads) until they are all the same. The *actual* differential isn't critical,
but 11 degC (20 degF) is the norm unless you have a condensing boiler - so a
flow temp of 82 degC and a return temp of 71 degC would be good. If, when
you've got all the rads with the same drop, this drop is significantly more
than 11 degC (except in the case of a condensing boiler) you need to
increase the overall flow rate by turning the pump up a notch or two, if
it's adjustable.

The flow (inlet) temperatures should all be very close to boiler outlet
temperature. If any are significantly less than this, you need to
investigate the pipework.
--
Cheers,
Set Square
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