I noticed something when trying to refill and bleed the radiators on
our combi sealed system. All the rads have thermostatic valves on
them. All the normal valves on the other end of the rads are fully
open.

When trying to bleed them, I noticed that with all the thermostatic
valves set to max, none of the rads seemed to get hot. I had to shut
the thermostatic valves on all of them, and go round opening them one
at a time to check the rad was getting hot and bleed it.

I can see why this would happen, but is this correct, and what should
I do about it? I wonder if closing some of the tap valves on the
radiators partially would improve things. I have seen mention of
balancing radiators - is this what this refers to?

In an earlier contribution to this discussion,
John Carlyle-Clarke wrote:

I noticed something when trying to refill and bleed the radiators on
our combi sealed system. All the rads have thermostatic valves on
them. All the normal valves on the other end of the rads are fully
open.

When trying to bleed them, I noticed that with all the thermostatic
valves set to max, none of the rads seemed to get hot. I had to shut
the thermostatic valves on all of them, and go round opening them one
at a time to check the rad was getting hot and bleed it.

I can see why this would happen, but is this correct, and what should
I do about it? I wonder if closing some of the tap valves on the
radiators partially would improve things. I have seen mention of
balancing radiators - is this what this refers to?

Even with TRV, you need to balance the system - by adjusting the lock-shield
valves - if you want all the rads to heat up evenly. Otherwise, some will
get hot first and, only when their TRVs have closed, will the others get
hot.

Do the balancing with the TRVs fully open, and with any room stats turned to
max - so that the system runs continuously during the balancing operation.
Measure the temperature drop across each radiator (an IR non-contact
thermometer is useful for this) and progessively turn down the lockshields
on the rads with the *lowest* drops until they are all more or less the
same. This is an iterative process, so you'll need to go round all the rads
several times.

When you're happy with the balance, return room stats and TRVs to their
normal settings.
--
Cheers,
Set Square
______
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In article ,
John Carlyle-Clarke wrote:
I have seen mention of balancing radiators - is this what this refers
to?

Yup. See FAQ for details on how to do.

--
*It ain't the size, it's... er... no, it IS ..the size.

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in
:

In article ,
John Carlyle-Clarke wrote:
I have seen mention of balancing radiators - is this what this
refers to?

Yup. See FAQ for details on how to do.



Will do! I think that was where I had "seen mention", but since I
didn't know what it was for, I didn't read it in detail.

Thanks again to all who responded.

"Set Square" wrote in message
...
In an earlier contribution to this discussion,
John Carlyle-Clarke wrote:

I noticed something when trying to refill and bleed the radiators on
our combi sealed system. All the rads have thermostatic valves on
them. All the normal valves on the other end of the rads are fully
open.

When trying to bleed them, I noticed that with all the thermostatic
valves set to max, none of the rads seemed to get hot. I had to shut
the thermostatic valves on all of them, and go round opening them one
at a time to check the rad was getting hot and bleed it.

I can see why this would happen, but is this correct, and what should
I do about it? I wonder if closing some of the tap valves on the
radiators partially would improve things. I have seen mention of
balancing radiators - is this what this refers to?

Even with TRV, you need to balance the system - by adjusting the
lock-shield
valves - if you want all the rads to heat up evenly. Otherwise, some will
get hot first and, only when their TRVs have closed, will the others get
hot.

Do the balancing with the TRVs fully open, and with any room stats turned
to
max - so that the system runs continuously during the balancing operation.
Measure the temperature drop across each radiator (an IR non-contact
thermometer is useful for this) and progessively turn down the lockshields
on the rads with the *lowest* drops until they are all more or less the
same. This is an iterative process, so you'll need to go round all the
rads
several times.

When you're happy with the balance, return room stats and TRVs to their
normal settings.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.



I was going to balance my raditors but couldn't be bothered in the end as
they all heat up within a few minutes anyway.

Is there really any point in balancing a combi powered sealed system?
Surely the fact that the boiler output generally far exceeds that required
by the CH system suggests so. When I spec'd up my system the calculation
gave a requirement of something like 11kw - the boiler I bought to give a
good shower flow is 28kw. Maybe microbore systems are a factor as it may be
more difficult to pump the water down the further reaches of the system?

In an earlier contribution to this discussion,
Brett Jackson wrote:

"Set Square" wrote in message
...
In an earlier contribution to this discussion,
John Carlyle-Clarke wrote:

I noticed something when trying to refill and bleed the radiators on
our combi sealed system. All the rads have thermostatic valves on
them. All the normal valves on the other end of the rads are fully
open.

When trying to bleed them, I noticed that with all the thermostatic
valves set to max, none of the rads seemed to get hot. I had to
shut the thermostatic valves on all of them, and go round opening
them one at a time to check the rad was getting hot and bleed it.

I can see why this would happen, but is this correct, and what
should I do about it? I wonder if closing some of the tap valves
on the radiators partially would improve things. I have seen
mention of balancing radiators - is this what this refers to?

Even with TRV, you need to balance the system - by adjusting the
lock-shield valves - if you want all the rads to heat up evenly.
Otherwise, some will get hot first and, only when their TRVs have
closed, will the others get hot.

Do the balancing with the TRVs fully open, and with any room stats
turned to max - so that the system runs continuously during the
balancing operation. Measure the temperature drop across each
radiator (an IR non-contact thermometer is useful for this) and
progessively turn down the lockshields on the rads with the *lowest*
drops until they are all more or less the same. This is an iterative
process, so you'll need to go round all the rads several times.

When you're happy with the balance, return room stats and TRVs to
their normal settings.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.



I was going to balance my raditors but couldn't be bothered in the
end as they all heat up within a few minutes anyway.

Is there really any point in balancing a combi powered sealed system?
Surely the fact that the boiler output generally far exceeds that
required by the CH system suggests so. When I spec'd up my system
the calculation gave a requirement of something like 11kw - the
boiler I bought to give a good shower flow is 28kw. Maybe microbore
systems are a factor as it may be more difficult to pump the water
down the further reaches of the system?

With *any* system with a lot of radiators in parallel, the water will take
the line of least resistance. If one or two radiators are more or less
resistance free, and can take most of the pump's output, other larger
radiators on a higher resistance path may never get very hot. The boiler's
(over-) capacity doesn't really come into it - this will never be harnessed
unless an adequate flow can be got to *all* rads - the boiler will simply
modulate down, or cycle on its internal stat.

[A motoring analogy would be a 4x4 car with a very powerful engine, with 1
or 2 of its wheels spinning in the mud. Until you control the wheelspin you
can't harness the power].

Balancing - which means restricting the flow to the rads with the least
resistance - will mean that an adequate flow of hot water arrives at *all*
radiators, enabling the boiler output to be used properly.
--
Cheers,
Set Square
______
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