Please help; upstairs has 1 rad on landing (hot), next is the toilet
(hot),small bedroom barely luke warm , 2nd bedroom barely luke warm ,finally
main bedroom stone cold.
when bleeding main bedroom rad a constant flow of water comes out with no
hissing. However in the small and 2nd bedroom the water comes out with
hissing also not a constant stream.I have been bleeding said rads but it
make any difference to the rads heat.I seem to have emptied bucket loads of
water from the system - is this right?-do i just keep on doing what i'm
doing untill the air goes?
Any ideas, suggestions gratefully received
It sounds as if you might be getting some air in as you bleed. I assume that
it is a vented system with a small feed/expansion tank in the attic - rather
than a sealed system with a filling loop and expansion vessel?
Make sure that there is some water in the feed/expansion tank - at least a
couple of inches to cover the outlet, but not too much - and that the ball
valve isn't stuck. [If this tank becomes empty, you'll suck air rather water
into the system when you open a bleed valve].
If there is a tap or gate valve on the feed pipe from the feed/expansion
tank into the system make sure it is open.
You could have an air lock in one pipe to each rad, which doesn't clear when
you bleed it because the replacement water comes via the other pipe. In
order to eliminate this possibility, bleed each rad twice - once through
each pipe. In other words, turn off one valve and bleed until you get a
steady stream of water - then close that valve and open the other one and
repeat the process. Finally open the other valve and, if the system has been
balanced, make sure you leave the lockshield valve in the same partially
open position as when you started. [When you close the lockshields, count
how many complete and partial turns it takes to close them, so that you can
subsequently open them again by the same amount].
If, when all the rads are fully bled, some still don't get hot, you may have
to re-balance the system by turning down the lockshields on the hottest rads
to increase the resistance of these - which will provide a bit more urge for
the water to flow through the cooler rads. It will always take the easiest
route round the system!
The need for radiators to be bled, is usually shown up by the fact that
the lower section will become hot, whilst the upper section stays cold
where air is trapped. They idea is to simply let the air out and and
stop when water appears.
When the heating is actually running (boiler firing) you should be able
to feel the hot water appear in the pipe as it makes its way to the
radiator. Each radiator has two valves, one for turning it on and off,
the other (which is identical, apart from lacking a handle) is for
balancing the flow.
Your problem could be that either of the above valves are turned off,
or you have an airlock (a bubble of air in the pipework). To solve the
latter problem.... Make sure both valves are open on the problem
radiators, turn off all the other radiators in other rooms, then run
the heating. This should ensure airlocks are cleared. If this works,
try bleeding the radiators again.
There are a number of possible problems (and attendent solutions) here. To
determine which is likely, we need to know whether this behaviour has always
existed, has existed since some work was done to the system, has suddenly
occurred, or has built up over time.
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