On Wed, 22 Sep 2004 14:55:19 +0100, Set Square wrote:
In an earlier contribution to this discussion,
AK wrote:
I am going to balance my radiators this weekend, I just want to check
some facts that hopefully some of you can help me with.
I need to open up all the control and LSVs and find out what the flow
is and find the index radiator. As I understand it the control valve
should be where the flow is in and the LSV on the outflow. Two of my
radiators appear to the the other way round - is it a simple matter
of just swapping over the knob from the control valve and putting it
on the LSV?
Yes, provided the two valve bodies are the same, and one of them isn't a
thermostatic valve!
Do I leave the index radiator fully open and work back to the boiler
or do I start from the radiator closest to the boiler?
Neither. Firstly, go round and measure and record the temperature drop
across *every* radiator. You will need a non-contact IR thermometer to be
able to do this is a reasonable time. Then turn down the LSVs on the rads
with the *lowest* drops - regardless of their position relative to the
boiler. This will restrict the flow - and increase the drop - of these, so
starting to even things up. Aim to get all the drops more or less the same -
without worrying too much about the *actual* value at this stage. It is an
iterative process - because decreasing the flow on one rad will increase it
on the others - so you'll have to go round the lot several times - allowing
a bit of time for any adjustments to take effect. The LSV on the rad with
the largest drop should remain fully open at all times.
From what I understand I might have to adjust the speed of the pump.
I have no idea how to do that! I have a Potterton Puma 100 boiler
and I can't even see a pump let alone adjust the speed! I understand
that some boilers have automatic pumps - is that right? Does my
boiler have one?
Is it correct that the drop needs to be 20 deg F?
Once all the drops are the same, you can adjust the pump speed - if
necessary - to achieve the desired value. For a conventional
(non-condensing) boiler, the norm is 11 degC (20 degF). If the drop is
significantly less than this, slow the pump down a bit - and vice versa. A
bit of fine tuning on the rads may be needed after this. [Don't be *too*
much of a perfectionist - it isn't an exact science!]
[I've no idea about your specific boiler/pump. Some boilers have a pump
inside the casing. Some systems use external pumps - often in the airing
cupboard. Once you find the pump, you should find a speed control lever or
knob on the side somewhere].
One other point worth noting: When you're rushing round measuring one rad
after another, you need the flow temperature to stay as constant as
possible - otherwise you won't be comparing apples with apples. This means
running the system flat out - with the room stat turned up to max. This time
of year, you'll probably need to open a few doors and windows while you do
it in order to dump the heat.
I think Set Sqaure has covered most of the points.
It makes no difference which valve you choose as the locksheild (for
balancing) and which you choose as the user valve. However generaly one
valve or other will be the more convinient for a user valve.
Obviously if one of the valves is a TRV then the other is a lockshield.
Not most valves have just about no effect until the last 1/2 a turn to
closed. Beaware that older valves can have a certain amount of backlash in
them so adjust them down to the settings if you need to open one up then
open it up a lot then down to what you what.
Finally setting the closest 1/3 of all the radiators to the boiler (as the
pipes run not as the tape measures) to about 1/2 turn open rather than
fully open [1] might save you one whole cycle of measurements. [2]
[1] All non-quarter turn valves are fully opened if they are open full on
less about 1/4 turn. This is too prevent them jamming in the open
position.
[2] This would be the finish of the subject for the mediocre professionals.
--
Ed Sirett - Property maintainer and registered gas fitter.
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