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Andy Hall
 
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Default FAQ Question re. central heating

On Mon, 11 Aug 2003 17:04:21 +0100, "Jonathan"
wrote:

Hi All,

Just reading the FAQ on central heating at
http://www.cucumber.demon.co.uk/diy_test/Q2.12.html

It says "After installation and commissioning, a new central heating system
should be balanced." And says: The "...aim of balancing is to achieve the
correct temperature drop across the boiler flow & return pipes (11C)."

I assume that in layman's terms this means, "... so that the water that goes
back to the boiler is cold enough to need re-heating, yet warm enough to
have delivered sufficient heat to the last radiator in the chain? Is that
right?

Sorry if this is a stupid question...

Jonathan



It's that and also to achieve the correct flow through each radiator.
When a system is designed, the radiators are sized to compensate for
the heat loss through the surfaces and to changes of air. The
radiator output is specified for a certain temperature drop across the
radiator and this will imply a certain flow rate (dependent on the
size of the radiator).

The plumbing is normally also designed to provide enough flow rate to
all radiators, but because of different pipe lengths and sizes there
will naturally be incorrect flow rates on some radiators.

In modern systems, the radiators are not in a "chain" as such but
connected from the boiler flow pipe to the return. If you compare
with an electrical circuit, this is a parallel connection not a series
one.

If you consider a small radiator quite close to the boiler and a large
one much further away, naturally speaking the flow would tend to go
through the nearer one because it is the line of least resistance.

Balancing basically entails reducing the flow through these lower
resistance radiators so that more water flows through the larger or
higher resistance ones. This is an iterative process to some extent
because adjusting each radiator, affects the others to a degree.

The methods in the FAQ are how to do it properly with a thermometer,
so that you get the correct flows everywhere. It is time consuming,
but worth doing.





..andy

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Jonathan
 
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Default FAQ Question re. central heating

Thanks for that - much clearer now. I can see that this is going to be my
next obsession, now that I've got over my last one about oiling Ikea wooden
kitchen worktops...

Jonathan



"Andy Hall" wrote in message
...
On Mon, 11 Aug 2003 17:04:21 +0100, "Jonathan"
wrote:

Hi All,

Just reading the FAQ on central heating at
http://www.cucumber.demon.co.uk/diy_test/Q2.12.html

It says "After installation and commissioning, a new central heating

system
should be balanced." And says: The "...aim of balancing is to achieve

the
correct temperature drop across the boiler flow & return pipes (11C)."

I assume that in layman's terms this means, "... so that the water that

goes
back to the boiler is cold enough to need re-heating, yet warm enough to
have delivered sufficient heat to the last radiator in the chain? Is that
right?

Sorry if this is a stupid question...

Jonathan



It's that and also to achieve the correct flow through each radiator.
When a system is designed, the radiators are sized to compensate for
the heat loss through the surfaces and to changes of air. The
radiator output is specified for a certain temperature drop across the
radiator and this will imply a certain flow rate (dependent on the
size of the radiator).

The plumbing is normally also designed to provide enough flow rate to
all radiators, but because of different pipe lengths and sizes there
will naturally be incorrect flow rates on some radiators.

In modern systems, the radiators are not in a "chain" as such but
connected from the boiler flow pipe to the return. If you compare
with an electrical circuit, this is a parallel connection not a series
one.

If you consider a small radiator quite close to the boiler and a large
one much further away, naturally speaking the flow would tend to go
through the nearer one because it is the line of least resistance.

Balancing basically entails reducing the flow through these lower
resistance radiators so that more water flows through the larger or
higher resistance ones. This is an iterative process to some extent
because adjusting each radiator, affects the others to a degree.

The methods in the FAQ are how to do it properly with a thermometer,
so that you get the correct flows everywhere. It is time consuming,
but worth doing.





.andy

To email, substitute .nospam with .gl



  #3   Report Post  
Andrew McKay
 
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Default FAQ Question re. central heating

On Mon, 11 Aug 2003 17:04:21 +0100, "Jonathan"
wrote:

It says "After installation and commissioning, a new central heating system
should be balanced." And says: The "...aim of balancing is to achieve the
correct temperature drop across the boiler flow & return pipes (11C)."


Balancing involves making sure that the radiators on the system each
get a share of the water flowing thru the CH waterways. Water always
flows best thru the path of least resistance.

What you effectively do is close down the return valve of the
radiators (the valve which is fixed, which the user doesn't crank the
handle of), thus restricting the flow to each radiator. That
restriction ensures that there is enough pressure in the system to
force water to the other radiators. Getting those return valves set up
correctly is a bit of an art. When I've done this in the past I've
started by closing down the return valve completely, then unwinding by
2 complete turns.

Andrew

Do you need a handyman service? Check out our
web site at http://www.handymac.co.uk
  #4   Report Post  
IMM
 
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Default FAQ Question re. central heating


"Jonathan" wrote in message
...
Hi All,

Just reading the FAQ on central heating at
http://www.cucumber.demon.co.uk/diy_test/Q2.12.html

It says "After installation and commissioning, a new central heating

system
should be balanced." And says: The "...aim of balancing is to achieve the
correct temperature drop across the boiler flow & return pipes (11C)."

I assume that in layman's terms this means, "... so that the water that

goes
back to the boiler is cold enough to need re-heating, yet warm enough to
have delivered sufficient heat to the last radiator in the chain? Is that
right?

Sorry if this is a stupid question...

Jonathan

Install a micro-bore system with manifolds. They are self balancing if the
rads are sized reasonably correct. Then install an auto variable speed
Grundfos Alpha pump.

Best is a heat bank with the CH manifolds taken off the bottom of the
cylinder. The boiler will be self balancing and so will the rads. A win,
win situation all around in DHW response, commissioning and simplicity.



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Ed Sirett
 
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Default FAQ Question re. central heating

IMM wrote:
=


"Jonathan" wrote in message
...
Hi All,

Just reading the FAQ on central heating at
http://www.cucumber.demon.co.uk/diy_test/Q2.12.html

It says "After installation and commissioning, a new central heating

system
should be balanced." And says: The "...aim of balancing is to achiev=

e the
correct temperature drop across the boiler flow & return pipes (11=B0=

C)."

I assume that in layman's terms this means, "... so that the water th=

at
goes
back to the boiler is cold enough to need re-heating, yet warm enough=

to
have delivered sufficient heat to the last radiator in the chain? Is =

that
right?

Sorry if this is a stupid question...

Jonathan
=


Install a micro-bore system with manifolds. They are self balancing if=

the
rads are sized reasonably correct. Then install an auto variable speed=


Grundfos Alpha pump.
=


Haven't we been here before? =

ISTR that we had a discussion about this and noted that microbore
systems might be a bit less unbalanced at the outset but that was about
all. =



-- =

Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html


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IMM
 
Posts: n/a
Default FAQ Question re. central heating


"Ed Sirett" wrote in message
...
IMM wrote:

"Jonathan" wrote in message
...
Hi All,

Just reading the FAQ on central heating at
http://www.cucumber.demon.co.uk/diy_test/Q2.12.html

It says "After installation and commissioning, a new central heating

system
should be balanced." And says: The "...aim of balancing is to achieve

the
correct temperature drop across the boiler flow & return pipes (11C)."

I assume that in layman's terms this means, "... so that the water that

goes
back to the boiler is cold enough to need re-heating, yet warm enough to
have delivered sufficient heat to the last radiator in the chain? Is

that
right?

Sorry if this is a stupid question...

Jonathan

Install a micro-bore system with manifolds. They are self balancing if

the
rads are sized reasonably correct. Then install an auto variable speed
Grundfos Alpha pump.

Haven't we been here before?
ISTR that we had a discussion about this and noted that microbore
systems might be a bit less unbalanced at the outset but that was about
all.

No. sized right balanced all the way. Have a an Alpha and TRVs all around
the anomalies will be trimmed out. Great for inexperienced DIYers.



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Andy Hall
 
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Default FAQ Question re. central heating

On Tue, 12 Aug 2003 22:38:43 +0100, "IMM" wrote:




Install a micro-bore system with manifolds. They are self balancing if

the
rads are sized reasonably correct. Then install an auto variable speed
Grundfos Alpha pump.

Haven't we been here before?
ISTR that we had a discussion about this and noted that microbore
systems might be a bit less unbalanced at the outset but that was about
all.

No. sized right balanced all the way. Have a an Alpha and TRVs all around
the anomalies will be trimmed out. Great for inexperienced DIYers.


It seems as though we have. Inaccurate information and put downs......





---


..andy

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  #8   Report Post  
IMM
 
Posts: n/a
Default FAQ Question re. central heating


"Andy Hall" wrote in message
...
On Tue, 12 Aug 2003 22:38:43 +0100, "IMM" wrote:


Install a micro-bore system with manifolds. They are self balancing if

the
rads are sized reasonably correct. Then install an auto variable speed
Grundfos Alpha pump.

Haven't we been here before?
ISTR that we had a discussion about this and noted that microbore
systems might be a bit less unbalanced at the outset but that was about
all.

No. sized right balanced all the way. Have a an Alpha and TRVs all

around
the anomalies will be trimmed out. Great for inexperienced DIYers.


It seems as though we have. Inaccurate information and put downs......


There was lots of inaccurate information by know-it-alls.


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  #9   Report Post  
Andy Hall
 
Posts: n/a
Default FAQ Question re. central heating

On Tue, 12 Aug 2003 23:06:03 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Tue, 12 Aug 2003 22:38:43 +0100, "IMM" wrote:


Install a micro-bore system with manifolds. They are self balancing if
the
rads are sized reasonably correct. Then install an auto variable speed
Grundfos Alpha pump.

Haven't we been here before?
ISTR that we had a discussion about this and noted that microbore
systems might be a bit less unbalanced at the outset but that was about
all.

No. sized right balanced all the way. Have a an Alpha and TRVs all

around
the anomalies will be trimmed out. Great for inexperienced DIYers.


It seems as though we have. Inaccurate information and put downs......


There was lots of inaccurate information by know-it-alls.


Quite.


---


..andy

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Jonathan
 
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Default FAQ Question re. central heating

Thanks for the info Phil! And thanks everyone for compiling these FAQs! Out
of date or not, they're wonderful references.

JJ



"Phil Addison" wrote in message
...
On Mon, 11 Aug 2003 17:04:21 +0100, "Jonathan"
wrote:

Just reading the FAQ on central heating at
http://www.cucumber.demon.co.uk/diy_test/Q2.12.html


Actually, you have found an out of date copy of the FAQ. The current
version of the Balancing FAQ is at
http://www.diyfaq.org.uk/plumbing/rad-balance.html

It says "After installation and commissioning, a new central heating

system
should be balanced." And says: The "...aim of balancing is to achieve

the
correct temperature drop across the boiler flow & return pipes (11C)."

I assume that in layman's terms this means, "... so that the water that

goes
back to the boiler is cold enough to need re-heating, yet warm enough to
have delivered sufficient heat to the last radiator in the chain? Is

that
right?

Sorry if this is a stupid question...


No, it's not, given that you were reading an obsolete version that has
been updated to correct the very confusion that you refer to.

Ask again if the current version leaves you with questions. Also, there
have been numerous posts on balancing radiators in the past so a google
search could be worthwhile.

--
Phil Addison
The uk.d-i-y FAQ is at http://www.diyfaq.org.uk/
Remove NOSPAM from address to reply





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IMM
 
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Default FAQ Question re. central heating


"IMM" wrote in message
...

"Jonathan" wrote in message
...
Hi All,

Just reading the FAQ on central heating at
http://www.cucumber.demon.co.uk/diy_test/Q2.12.html

It says "After installation and commissioning, a new central heating

system
should be balanced." And says: The "...aim of balancing is to achieve

the
correct temperature drop across the boiler flow & return pipes (11C)."

I assume that in layman's terms this means, "... so that the water that

goes
back to the boiler is cold enough to need re-heating, yet warm enough to
have delivered sufficient heat to the last radiator in the chain? Is

that
right?

Sorry if this is a stupid question...

Jonathan

Install a micro-bore system with manifolds. They are self balancing if

the
rads are sized reasonably correct. Then install an auto variable speed
Grundfos Alpha pump.

Best is a heat bank with the CH manifolds taken off the bottom of the
cylinder. The boiler will be self balancing and so will the rads. A win,
win situation all around in DHW response, commissioning and simplicity.


Just to add:

Plumbing Mechanical Service Book 2, a NVQ plumbing book. This is not a DIY
book so please don't buy. It has a section on heating, and a sub section on
Mini-bore on page 170. It says:

"If the manifolds can be situated in such a way that the branch flow and
return to each radiator is approximately the same length, the frictional
resistance will also be approx the same, making the system self balancing".

And on page 171:

"In a well-designed system balancing should not be necessary as the aim is
to keep all pipe runs to heat emitters at, or near, as possible, the same
lengths."

And on page 172, there is a cut-away of a twin entry rad valve without
lockshield adjustment because in properly designed mini-bore systems, which
is easy to do, balancing is not required.




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Phil Addison
 
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Default FAQ Question re. central heating

On Tue, 12 Aug 2003 23:51:40 +0100, "IMM" wrote:

Just to add:

Plumbing Mechanical Service Book 2, a NVQ plumbing book. This is not a DIY
book so please don't buy. It has a section on heating, and a sub section on
Mini-bore on page 170. It says:

"If the manifolds can be situated in such a way that the branch flow and
return to each radiator is approximately the same length, the frictional
resistance will also be approx the same, making the system self balancing".


That is plain wrong. Making all the pipes the same length will indeed
make the each rad feed have the same resistance. But that is NOT what is
required. Different sized rads require different flow rates otherwise
the small rads will steal flow that is needed by the large ones.
Balancing is the process that adds the extra resistance to the small
rads to achieve this.

It is not at all unusual for so called professional authors to get these
things totally wrong. Hopefully, it is only the writer of that book that
is ignorant rather than the institute he wrote it for. I recommend that
students of NVQ do not buy it either.

And on page 171:

"In a well-designed system balancing should not be necessary as the aim is
to keep all pipe runs to heat emitters at, or near, as possible, the same
lengths."


Same error carried over. very bad show. Plus in the vast majority of
installations there is now way the runs can all be the same length.
Unless the architect bases the whole property design on achieving
equidistanced and equisized radiators. Can't see it getting on Grand
Designs though.

And on page 172, there is a cut-away of a twin entry rad valve without
lockshield adjustment because in properly designed mini-bore systems, which
is easy to do, balancing is not required.


Sigh....

--
Phil Addison
The uk.d-i-y FAQ is at http://www.diyfaq.org.uk/
Remove NOSPAM from address to reply
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IMM
 
Posts: n/a
Default FAQ Question re. central heating

"Phil Addison" wrote in message
...
On Tue, 12 Aug 2003 23:51:40 +0100, "IMM" wrote:

Just to add:

Plumbing Mechanical Service Book 2,
a NVQ plumbing book. This is not a DIY
book so please don't buy. It has a section
on heating, and a sub section on
Mini-bore on page 170. It says:

"If the manifolds can be situated in such
a way that the branch flow and
return to each radiator is approximately
the same length, the frictional
resistance will also be approx the same,
making the system self balancing".


That is plain wrong.


It is plain right!

Making all the pipes the same length will indeed
make the each rad feed have the same resistance. But that is NOT what is
required. Different sized rads require different flow rates otherwise
the small rads will steal flow that is needed by the large ones.
Balancing is the process that adds the extra resistance to the small
rads to achieve this.


Each rad will not have the same pipe sizes. A small rad may only have 8mm
and a larger rad 12mm. The pipe sizes will create resistance in themselves.
Manufacturers did not make lockshieldless valves for nothing.

Sigh....


Yes sigh



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geoff
 
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Default FAQ Question re. central heating

In message , IMM
writes

Plumbing Mechanical Service Book 2, a NVQ plumbing book. This is not a DIY
book so please don't buy. It has a section on heating, and a sub section on
Mini-bore on page 170. It says:

"If the manifolds can be situated in such a way that the branch flow and
return to each radiator is approximately the same length, the frictional
resistance will also be approx the same, making the system self balancing".

And on page 171:

"In a well-designed system balancing should not be necessary as the aim is
to keep all pipe runs to heat emitters at, or near, as possible, the same
lengths."

And on page 172, there is a cut-away of a twin entry rad valve without
lockshield adjustment because in properly designed mini-bore systems, which
is easy to do, balancing is not required.


And I thought that NVQ was for people too thick to take "O" levels

--
geoff
  #15   Report Post  
Andy Hall
 
Posts: n/a
Default FAQ Question re. central heating

On Tue, 12 Aug 2003 23:51:40 +0100, "IMM" wrote:



Install a micro-bore system with manifolds. They are self balancing if

the
rads are sized reasonably correct. Then install an auto variable speed
Grundfos Alpha pump.

Best is a heat bank with the CH manifolds taken off the bottom of the
cylinder. The boiler will be self balancing and so will the rads. A win,
win situation all around in DHW response, commissioning and simplicity.


Just to add:

Plumbing Mechanical Service Book 2, a NVQ plumbing book. This is not a DIY
book so please don't buy.


The recommendation not to buy is a reasonable one, but not because it
is an NVQ book but because the information is obviously wrong. If it
is as incorrect in other areas as it is in this it could well be
dangerous.


It has a section on heating, and a sub section on
Mini-bore on page 170. It says:

"If the manifolds can be situated in such a way that the branch flow and
return to each radiator is approximately the same length, the frictional
resistance will also be approx the same, making the system self balancing".


That is incorrect, even if it could be done anyway. For this to work,
the radiators would also have to be identically sized.

For example, a living room might require a 3kW radiator, while a small
bedroom only 750W. This immediately implies that the living room
radiator requires four times the flow of water as the bedroom one.
If they are connected through equal lengths of pipe from the same
manifold, then the flow rates would be equal. That is not what is
required, and the system is not self balancing.




And on page 171:

"In a well-designed system balancing should not be necessary as the aim is
to keep all pipe runs to heat emitters at, or near, as possible, the same
lengths."


That is also clearly wrong because again it would only work for
radiators of the same size.



And on page 172, there is a cut-away of a twin entry rad valve without
lockshield adjustment because in properly designed mini-bore systems, which
is easy to do, balancing is not required.


It is easy to do, but that is not the way to do it. These twin entry
valves are not commonly found at heating suppliers or on their web
sites, presumably because they are not popular. If this is the basis
of their use, I can see why.


I have a system connected mainly with 8mm pipe to manifolds. There
were a couple of radiators in a living room which were over the limit
for the size of pipe. During my refurbishment to allow lower
temperature operation, these were replaced with larger capacity
radiators and replumbed in 15mm.

It is certainly true that microbore tube helps a bit with the
balancing in the sense that the sensitivity of the lockshield valve is
reduced, making it easier to adjust.

This is fairly obvious behaviour and analogous to an electrical
circuit with a fixed and variable resistor in series. The
adjustability of the current through the load is reduced as compared
with having a variable resistor only.

There are advantages of microbore, that is true, but self balancing is
not one of them.







---


..andy

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IMM
 
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Default FAQ Question re. central heating


"Phil Addison" wrote in message
...
On Wed, 13 Aug 2003 00:36:41 +0100, "IMM" wrote:

"Phil Addison" wrote in message
...
On Tue, 12 Aug 2003 23:51:40 +0100, "IMM" wrote:

Just to add:

Plumbing Mechanical Service Book 2,
a NVQ plumbing book. This is not a DIY
book so please don't buy. It has a section
on heating, and a sub section on
Mini-bore on page 170. It says:

"If the manifolds can be situated in such
a way that the branch flow and
return to each radiator is approximately
the same length, the frictional
resistance will also be approx the same,
making the system self balancing".

That is plain wrong.


It is plain right!

Making all the pipes the same length will indeed
make the each rad feed have the same resistance. But that is NOT what

is
required. Different sized rads require different flow rates otherwise
the small rads will steal flow that is needed by the large ones.
Balancing is the process that adds the extra resistance to the small
rads to achieve this.


Each rad will not have the same pipe sizes. A small rad may only have

8mm
and a larger rad 12mm. The pipe sizes will create resistance in

themselves.
Manufacturers did not make lockshieldless valves for nothing.


Why on earth fiddle with different
sized pipes to (attempt to) balance
the rads. Just use one size and balance
with the LSV. calculating what
length of what resistance would be
needed to correctly balance is quite
beyond a c/h fitter, wheras turning a LSV is not.


You are supposed to size up the pipe sizes correctly. Sizing up for each
rad on a manifold system is very easy. Attempting to do it on a 22/15mm
small bore system is far more complex.

I bought a new house a few years ago in which the all the rad circuits
were plumbed in 10mm insulated microbore. The lounge radiator was a very
large double, about 2.5 kw IIRC, and at the far end of the lounge
fromthe manifold. It would not get hot enough to warm the room. I checed
the design and found 15mm would be required to feed the load over that
long distance. The plumber, then his boss, all tried to tell me it was
all-right really, because the flow side of the radiators was really hot.
It was only when I got the builder boss in on acold and demonstrtaed
the room was not up to temperature that the reluctantly agreed to change
the microbore feed to 15mm.

But guess what? When I got back from work, I found that because it was
only the return side that was cool they only changed the return feed to
15mm, some 4m in length, and there was hardly any improvement. It took a
long conference with the lot of them to get the feed changed as well.

After that the rad got fully hot and the lounge temperature was fine.


That was because they were plumbers. They obviously didn't have much of a
clue.



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  #17   Report Post  
IMM
 
Posts: n/a
Default FAQ Question re. central heating


"Andy Hall" wrote in message
...
On Tue, 12 Aug 2003 23:51:40 +0100, "IMM" wrote:



Install a micro-bore system with manifolds. They are self balancing if

the
rads are sized reasonably correct. Then install an auto variable speed
Grundfos Alpha pump.

Best is a heat bank with the CH manifolds taken off the bottom of the
cylinder. The boiler will be self balancing and so will the rads. A

win,
win situation all around in DHW response, commissioning and simplicity.


Just to add:

Plumbing Mechanical Service Book 2, a NVQ plumbing book. This is not a

DIY
book so please don't buy.


The recommendation not to buy is a reasonable one, but not because it
is an NVQ book but because the information is obviously wrong.


Don't ramble. You haven't a clue, so don't attempt to think anout it. Just
accept that is the way.

snip drivel


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Andy Hall
 
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Default FAQ Question re. central heating

On Wed, 13 Aug 2003 11:03:27 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Tue, 12 Aug 2003 23:51:40 +0100, "IMM" wrote:



Install a micro-bore system with manifolds. They are self balancing if
the
rads are sized reasonably correct. Then install an auto variable speed
Grundfos Alpha pump.

Best is a heat bank with the CH manifolds taken off the bottom of the
cylinder. The boiler will be self balancing and so will the rads. A

win,
win situation all around in DHW response, commissioning and simplicity.

Just to add:

Plumbing Mechanical Service Book 2, a NVQ plumbing book. This is not a

DIY
book so please don't buy.


The recommendation not to buy is a reasonable one, but not because it
is an NVQ book but because the information is obviously wrong.


Don't ramble. You haven't a clue, so don't attempt to think anout it. Just
accept that is the way.


It struck me that the author of that book probably does the same thing
as you - capturing unsubstantiable and incorrect information from web
sites and various other sources and assuming that because it is in
print or electronic format, it must be correct.

Naive in the extreme.




..andy

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IMM
 
Posts: n/a
Default FAQ Question re. central heating


"Andy Hall" wrote in message
...
On Wed, 13 Aug 2003 11:03:27 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Tue, 12 Aug 2003 23:51:40 +0100, "IMM" wrote:



Install a micro-bore system with manifolds. They are self balancing

if
the
rads are sized reasonably correct. Then install an auto variable

speed
Grundfos Alpha pump.

Best is a heat bank with the CH manifolds taken off the bottom of

the
cylinder. The boiler will be self balancing and so will the rads.

A
win,
win situation all around in DHW response, commissioning and

simplicity.

Just to add:

Plumbing Mechanical Service Book 2, a NVQ plumbing book. This is not a

DIY
book so please don't buy.

The recommendation not to buy is a reasonable one, but not because it
is an NVQ book but because the information is obviously wrong.


Don't ramble. You haven't a clue, so don't attempt to think anout it.

Just
accept that is the way.


It struck me that the author of that book probably does the same thing
as you - capturing unsubstantiable and incorrect information from web
sites and various other sources and assuming that because it is in
print or electronic format, it must be correct.

Naive in the extreme.


He happens to be correct. Strange in that a total amateur think differently.


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  #20   Report Post  
Andy Hall
 
Posts: n/a
Default FAQ Question re. central heating

On Wed, 13 Aug 2003 12:32:53 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Wed, 13 Aug 2003 11:03:27 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Tue, 12 Aug 2003 23:51:40 +0100, "IMM" wrote:



Install a micro-bore system with manifolds. They are self balancing

if
the
rads are sized reasonably correct. Then install an auto variable

speed
Grundfos Alpha pump.

Best is a heat bank with the CH manifolds taken off the bottom of

the
cylinder. The boiler will be self balancing and so will the rads.

A
win,
win situation all around in DHW response, commissioning and

simplicity.

Just to add:

Plumbing Mechanical Service Book 2, a NVQ plumbing book. This is not a
DIY
book so please don't buy.

The recommendation not to buy is a reasonable one, but not because it
is an NVQ book but because the information is obviously wrong.



It struck me that the author of that book probably does the same thing
as you - capturing unsubstantiable and incorrect information from web
sites and various other sources and assuming that because it is in
print or electronic format, it must be correct.

Naive in the extreme.


He happens to be correct. Strange in that a total amateur think differently.


Demonstrably not because this would not be in accordance with the
basic physical laws of fluid flow and heat transfer.

Are you sure you aren't the author?

This reminds me of a little anecdote - the Zanzibar Fable.

It's about two "professionals" who believe that they are absolutely
right and don't appreciate the ridculousness of their situation.



..andy

To email, substitute .nospam with .gl


  #21   Report Post  
IMM
 
Posts: n/a
Default FAQ Question re. central heating


"Andy Hall" wrote in message
news
On Wed, 13 Aug 2003 12:32:53 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Wed, 13 Aug 2003 11:03:27 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Tue, 12 Aug 2003 23:51:40 +0100, "IMM"

wrote:



Install a micro-bore system with manifolds. They are self

balancing
if
the
rads are sized reasonably correct. Then install an auto variable

speed
Grundfos Alpha pump.

Best is a heat bank with the CH manifolds taken off the bottom of

the
cylinder. The boiler will be self balancing and so will the

rads.
A
win,
win situation all around in DHW response, commissioning and

simplicity.

Just to add:

Plumbing Mechanical Service Book 2, a NVQ plumbing book. This is

not a
DIY
book so please don't buy.

The recommendation not to buy is a reasonable one, but not because

it
is an NVQ book but because the information is obviously wrong.



It struck me that the author of that book probably does the same thing
as you - capturing unsubstantiable and incorrect information from web
sites and various other sources and assuming that because it is in
print or electronic format, it must be correct.

Naive in the extreme.


He happens to be correct. Strange in that a total amateur think

differently.


Demonstrably not because this would not be in accordance with the
basic physical laws of fluid flow and heat transfer.

Are you sure you aren't the author?

This reminds me of a little anecdote - the Zanzibar Fable.

It's about two "professionals" who believe that they are absolutely
right and don't appreciate the ridculousness of their situation.


It was two "amateurs" here who thought they were right. And don't
appreciate the fools they are making of each other.


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IMM
 
Posts: n/a
Default FAQ Question re. central heating


"Phil Addison" wrote in message
...
On Wed, 13 Aug 2003 11:01:15 +0100, "IMM" wrote:


"Phil Addison" wrote in message
...
On Wed, 13 Aug 2003 00:36:41 +0100, "IMM" wrote:

"Phil Addison" wrote in message
...
On Tue, 12 Aug 2003 23:51:40 +0100, "IMM"

wrote:

Just to add:

Plumbing Mechanical Service Book 2,
a NVQ plumbing book. This is not a DIY
book so please don't buy. It has a section
on heating, and a sub section on
Mini-bore on page 170. It says:

"If the manifolds can be situated in such
a way that the branch flow and
return to each radiator is approximately
the same length, the frictional
resistance will also be approx the same,
making the system self balancing".

That is plain wrong.

It is plain right!

Making all the pipes the same length will indeed
make the each rad feed have the same resistance. But that is NOT

what
is
required. Different sized rads require different flow rates

otherwise
the small rads will steal flow that is needed by the large ones.
Balancing is the process that adds the extra resistance to the

small
rads to achieve this.

Each rad will not have the same pipe sizes. A small rad may only

have
8mm
and a larger rad 12mm. The pipe sizes will create resistance in

themselves.
Manufacturers did not make lockshieldless valves for nothing.

Why on earth fiddle with different
sized pipes to (attempt to) balance
the rads. Just use one size and balance
with the LSV. calculating what
length of what resistance would be
needed to correctly balance is quite
beyond a c/h fitter, wheras turning a LSV is not.


You are supposed to size up the pipe sizes correctly.


Obviously!! And I did not suggest otherwise.


You did. You said "Why on earth fiddle with different sized pipes".

If you had knowledge of
flow physics


If you knew anything about CH you would keep quiet.

you would know that
the 'correct' size is a bore that is
large enough to pass the required flow rate,
OR BIGGER.


No. The right size is the right size. not bigger or smaller.

Sizing up for each
rad on a manifold system is very easy.
Attempting to do it on a 22/15mm
small bore system is far more complex.


The calculations are identical,


The method is not. In a manifold system, you size uop the pipe from the
boiler to the manifolds. easy enough. Then from the manifold to the rads.
In a small bores it twists and turns with bores and tees.

Those that can't do the calculations,
and it appears that includes you,


snip you are a fool, I go no further


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  #23   Report Post  
IMM
 
Posts: n/a
Default FAQ Question re. central heating


"geoff" wrote in message
...
In message , IMM
writes

Plumbing Mechanical Service Book 2, a NVQ plumbing book. This is not a

DIY
book so please don't buy. It has a section on heating, and a sub section

on
Mini-bore on page 170. It says:

"If the manifolds can be situated in such a way that the branch flow and
return to each radiator is approximately the same length, the frictional
resistance will also be approx the same, making the system self

balancing".

And on page 171:

"In a well-designed system balancing should not be necessary as the aim

is
to keep all pipe runs to heat emitters at, or near, as possible, the same
lengths."

And on page 172, there is a cut-away of a twin entry rad valve without
lockshield adjustment because in properly designed mini-bore systems,

which
is easy to do, balancing is not required.


And I thought that NVQ was for people too thick to take "O" levels


Vocational me boy. Vocational. For people who where they are going.


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  #24   Report Post  
Andy Hall
 
Posts: n/a
Default FAQ Question re. central heating

On Thu, 14 Aug 2003 13:27:05 +0100, "IMM" wrote:


"geoff" wrote in message
...
In message , IMM
writes

Plumbing Mechanical Service Book 2, a NVQ plumbing book. This is not a

DIY
book so please don't buy. It has a section on heating, and a sub section

on
Mini-bore on page 170.


snip inaccurate information


And I thought that NVQ was for people too thick to take "O" levels


Vocational me boy. Vocational. For people who where they are going.


.... and here was me thinking that it meant Not Very Quick....

You live and learn.....


..andy

To email, substitute .nospam with .gl
  #25   Report Post  
IMM
 
Posts: n/a
Default FAQ Question re. central heating


"Andy Hall" wrote in message
...
On Thu, 14 Aug 2003 13:27:05 +0100, "IMM" wrote:


"geoff" wrote in message
...
In message , IMM


writes

Plumbing Mechanical Service Book 2, a NVQ plumbing book. This is not a

DIY
book so please don't buy. It has a section on heating, and a sub

section
on
Mini-bore on page 170.


snip inaccurate information


And I thought that NVQ was for people too thick to take "O" levels


Vocational me boy. Vocational. For people who know where they are going.


... and here was me thinking that it meant Not Very Quick....

You live and learn.....


You will have to do a lot more living and learning!


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