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James W
 
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Default Putting a double glazed pane in an old frame

I have a deep window frame above my front door. It currently has a
single glazed pane in it. I was wondering whether anyone has had any
experience getting a correct sized double glazed pane made up and
fitting it into the existing frame.

Are glazing companies willing to make a double glazed pane for this?
And would it be cheap enough to be worthwhile. Also, would the double
glazed pane fit OK into the existing pane? It is deep enough to
accomodate the pane from what I can tell.

Thanks in advance

Jim
  #2   Report Post  
Coherers
 
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Default Putting a double glazed pane in an old frame

You can get sealed units made up, however there are issues with respect to
getting the units to last. Apparently they will fail ( mist up) if not
fitted to allow for proper ventilation around the edges. And they require
deeper rebates.

Check out the following web site - they seem very knowledgeable on the
forum:

www.thewindowman.co.uk

There is an "e-book" for download there, giving the ins and outs of fitting
sealed units in old frames:

http://www.thewindowman.co.uk/Ebook_...s_drainage.pdf

Been meaning to try replacing one myself, but not got around to it yet...

"coherers"


"James W" wrote in message
om...
I have a deep window frame above my front door. It currently has a
single glazed pane in it. I was wondering whether anyone has had any
experience getting a correct sized double glazed pane made up and
fitting it into the existing frame.

Are glazing companies willing to make a double glazed pane for this?
And would it be cheap enough to be worthwhile. Also, would the double
glazed pane fit OK into the existing pane? It is deep enough to
accomodate the pane from what I can tell.

Thanks in advance

Jim



  #3   Report Post  
Grunff
 
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Default Putting a double glazed pane in an old frame

James W wrote:
I have a deep window frame above my front door. It currently has a
single glazed pane in it. I was wondering whether anyone has had any
experience getting a correct sized double glazed pane made up and
fitting it into the existing frame.

Are glazing companies willing to make a double glazed pane for this?
And would it be cheap enough to be worthwhile. Also, would the double
glazed pane fit OK into the existing pane? It is deep enough to
accomodate the pane from what I can tell.


You need to be able to accommodate a unit at least 12mm thick. Most good
DG companies will supply you with a sealed unit, and they are
surprisingly cheap. I recently bought 8 of them (1.5x1.2m average) at
about £50 each.

The key point is that it must not end up sitting in a puddle of water in
the frame. This is easily avoided through careful sealing.

--
Grunff
  #4   Report Post  
Mary Fisher
 
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Default Putting a double glazed pane in an old frame


"James W" wrote in message
om...
I have a deep window frame above my front door. It currently has a
single glazed pane in it. I was wondering whether anyone has had any
experience getting a correct sized double glazed pane made up and
fitting it into the existing frame.

Are glazing companies willing to make a double glazed pane for this?
And would it be cheap enough to be worthwhile. Also, would the double
glazed pane fit OK into the existing pane? It is deep enough to
accomodate the pane from what I can tell.


We've double glazed our whole house by getting the glass company to make
factory sealed units to exactly the size we specified. That's thirty five (I
think) units. Spouse fitted them over a couple of years so the cost - which
was VERY low - wasn't felt at all.

They've been perfect in every way. There has been absoutely no misting. They
were easy to fit (he does know what he's doing but with a little care and
intelligence anyone could do it - it's safer than single pane glazing). The
key is accurate measuring. For the largest panes - up to 4' square - it
needed two people because the units are heavy (on two ladders for 1st floor
lights); for others one person inside and one outside was a help but not
absolutely necessary. He did our 1st floor bedroom the week after being
discharged from hospital after a hip replacement.

What I like best is that we retain the timber frames and don't have the
reduced light which is inevitable with plastic frames. The relative cost was
unbelievably low and we were in control at all times. The only disruption
was one pane being out at any one time - at our convenience.

Go for it.

Mary

Thanks in advance

Jim



  #5   Report Post  
Andy Hall
 
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Default Putting a double glazed pane in an old frame

On Sun, 18 Jan 2004 20:04:12 -0000, "Mary Fisher"
wrote:


"James W" wrote in message
. com...
I have a deep window frame above my front door. It currently has a
single glazed pane in it. I was wondering whether anyone has had any
experience getting a correct sized double glazed pane made up and
fitting it into the existing frame.

Are glazing companies willing to make a double glazed pane for this?
And would it be cheap enough to be worthwhile. Also, would the double
glazed pane fit OK into the existing pane? It is deep enough to
accomodate the pane from what I can tell.


We've double glazed our whole house by getting the glass company to make
factory sealed units to exactly the size we specified. That's thirty five (I
think) units. Spouse fitted them over a couple of years so the cost - which
was VERY low - wasn't felt at all.

They've been perfect in every way. There has been absoutely no misting. They
were easy to fit (he does know what he's doing but with a little care and
intelligence anyone could do it - it's safer than single pane glazing). The
key is accurate measuring. For the largest panes - up to 4' square - it
needed two people because the units are heavy (on two ladders for 1st floor
lights); for others one person inside and one outside was a help but not
absolutely necessary. He did our 1st floor bedroom the week after being
discharged from hospital after a hip replacement.

What I like best is that we retain the timber frames and don't have the
reduced light which is inevitable with plastic frames. The relative cost was
unbelievably low and we were in control at all times. The only disruption
was one pane being out at any one time - at our convenience.

Go for it.

Mary


Are you talking about sash frames and windows here, Mary? How did you
fit in the units and did you have to add to the sash weights if they
were sashes?



..andy

To email, substitute .nospam with .gl


  #6   Report Post  
Mary Fisher
 
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Default Putting a double glazed pane in an old frame


"Andy Hall" wrote in message
...
On Sun, 18 Jan 2004 20:04:12 -0000, "Mary Fisher"
wrote:


"James W" wrote in message
. com...
I have a deep window frame above my front door. It currently has a
single glazed pane in it. I was wondering whether anyone has had any
experience getting a correct sized double glazed pane made up and
fitting it into the existing frame.

Are glazing companies willing to make a double glazed pane for this?
And would it be cheap enough to be worthwhile. Also, would the double
glazed pane fit OK into the existing pane? It is deep enough to
accomodate the pane from what I can tell.


We've double glazed our whole house by getting the glass company to make
factory sealed units to exactly the size we specified. That's thirty five

(I
think) units. Spouse fitted them over a couple of years so the cost -

which
was VERY low - wasn't felt at all.

They've been perfect in every way. There has been absoutely no misting.

They
were easy to fit (he does know what he's doing but with a little care and
intelligence anyone could do it - it's safer than single pane glazing).

The
key is accurate measuring. For the largest panes - up to 4' square - it
needed two people because the units are heavy (on two ladders for 1st

floor
lights); for others one person inside and one outside was a help but not
absolutely necessary. He did our 1st floor bedroom the week after being
discharged from hospital after a hip replacement.

What I like best is that we retain the timber frames and don't have the
reduced light which is inevitable with plastic frames. The relative cost

was
unbelievably low and we were in control at all times. The only disruption
was one pane being out at any one time - at our convenience.

Go for it.

Mary


Are you talking about sash frames and windows here, Mary? How did you
fit in the units and did you have to add to the sash weights if they
were sashes?


No, sorry, I should have specified.I suppose it they had been sashes I'd
have said so.

But I don't suppose he'd have been daunted by sashes and he has a collection
of lead which he occasionally casts into moulds for various purposes.
Working out the required added weight for the counterbalances would have
been the cerebral part of the exercise.

Mary





.andy

To email, substitute .nospam with .gl



  #7   Report Post  
Steve Walker
 
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Default Putting a double glazed pane in an old frame

On 18 Jan 2004 10:43:50 -0800, James W wrote:

I have a deep window frame above my front door. It currently has a
single glazed pane in it. I was wondering whether anyone has had any
experience getting a correct sized double glazed pane made up and
fitting it into the existing frame.

Are glazing companies willing to make a double glazed pane for this?
And would it be cheap enough to be worthwhile. Also, would the double
glazed pane fit OK into the existing pane? It is deep enough to
accomodate the pane from what I can tell.

Thanks in advance

Jim


Just in case you find that there is not enough depth for a double glazing
unit, it is possible to have a stepped unit made - ie the two panes of
glass are different sizes and the metal spacer is the size of the smaller
pane, allowing the unit to fit a rebate meant only for single glazing, held
in pace only by the larger pane.

Steve W
  #8   Report Post  
jacob
 
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Default Putting a double glazed pane in an old frame

Waste of money. If it's broken and needs replacing double glazing
still a waste of money - don't bother.

cheers

Jacob
  #9   Report Post  
Dave Plowman
 
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Default Putting a double glazed pane in an old frame

In article ,
James W wrote:
I have a deep window frame above my front door. It currently has a
single glazed pane in it. I was wondering whether anyone has had any
experience getting a correct sized double glazed pane made up and
fitting it into the existing frame.


Yup - did this recently.

Are glazing companies willing to make a double glazed pane for this?
And would it be cheap enough to be worthwhile. Also, would the double
glazed pane fit OK into the existing pane? It is deep enough to
accomodate the pane from what I can tell.


Yes - any decent glazier will order up a double glazed panel in any size.
But it can't just be fitted with putty - it needs to be fully sealed
against rain and must be in a flexible seal so when the frame moves
slightly it doesn't get subject to twisting, etc. The glazier will supply
materials and details.

If it's in a rebate it will probably have to be enlarged. If it's got
planted on beading, then this can be changed or moved.

--
*If a parsley farmer is sued, can they garnish his wages?

Dave Plowman London SW 12
RIP Acorn
  #10   Report Post  
jacob
 
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Default Putting a double glazed pane in an old frame

Heat loss through windows rule of thumb is about 10%.
Double glazing halves this and so saves 5% of heating component of
fuel bills.
Typically about £500 p.a. hence saving £25 p.a. Really not worth the
bother.
Higher proportion of heat lost through windows if the house is highly
insulated but the small saving is the same i.e. larger % of smaller
bill - still not worth it.
Add in rapid obsolescence of DG units makes it very costly - they all
mist up eventually.
Better to increase loft insulation, reduce draughts, thicker curtains
etc etc. Cheaper to install new gas condensing CH boiler will save
much more.
Double glazing expensive con.

cheers

Jacob


  #11   Report Post  
Mary Fisher
 
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Default Putting a double glazed pane in an old frame


"jacob" wrote in message
m...
Heat loss through windows rule of thumb is about 10%.
Double glazing halves this and so saves 5% of heating component of
fuel bills.
Typically about £500 p.a. hence saving £25 p.a. Really not worth the
bother.


There are other considerations than cost, even if your figures were
universally accurate.

Add in rapid obsolescence of DG units makes it very costly - they all
mist up eventually.


Not in my experience. It probably depends on the quality of the original
units.

Better to increase loft insulation, reduce draughts,


thicker curtains


During the day?

Double glazing increases the comfort of a house, you can sit (as we do)
close to uncurtained windows on the coldest of days and still be
comfortable.

Down draughts from single glazed windows can be shown by holding a candle
flame near to them. The candle will flicker and gutter, it won't with an
efficiently double glazed window.

etc etc. Cheaper to install new gas condensing CH boiler will save
much more.
Double glazing expensive con.


That depends on who does it. If you do it yourself (this IS a DIY ng) it is
not expensive and you have control of the whole process.

Yes, efficient insulation and draughtproofing are very important in the
whole scheme of things but you won't dissuade me about the desirability of
dg.

You seem to either believe what you have no experience of or have had an
unfortunate experience. It's not everyone's experience.

Mary


  #12   Report Post  
jacob
 
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Default Putting a double glazed pane in an old frame

In 'The Which Book of Plumbing & Central Heating' the heat loss quoted
for single glazed wooden windows is 5 W/sq.metre/deg C and for DG
wooden or plastic windows is 2.9 ditto. This means DG saves 42% heat
loss. Similar figures are quoted elsewhere, say approx 50% as a rule,
of average 10% heat loss of whole house i.e. about 5% overall.
If you work it out on paper every other way of reducing heat loss from
simple draught measures up to replacing old boiler with modern high
efficiency boiler, will cost less than whole house DG but save more or
at least be more cost efficient.
In other words DG is the last thing you should bother with - only
after putting into place ALL the other measures especially loft
insulation - and even then is not worth it unless you have money to
burn.
You can work it out for yourself.

cheers

Jacob
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Dave Plowman
 
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Default Putting a double glazed pane in an old frame

In article ,
jacob wrote:
In other words DG is the last thing you should bother with - only after
putting into place ALL the other measures especially loft insulation -
and even then is not worth it unless you have money to burn. You can
work it out for yourself.


Whilst this may be true, double glazing seems to reduce draughts, so the
overall temperature can often be reduced with no loss of comfort.

--
* What do they call a coffee break at the Lipton Tea Company? *

Dave Plowman London SW 12
RIP Acorn
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Simon Gardner
 
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Default Putting a double glazed pane in an old frame

In article ,
"Mary Fisher" wrote:

Double glazing increases the comfort of a house, you can sit (as we do)
close to uncurtained windows on the coldest of days and still be
comfortable.


Actually, one of the things I like about windows is you can sit next to
them if you want to be a bit cooler but everyone else doesn't.

OTOH Jacob's calculations are on heat loss and not including getting rid of
unwanted heat gain. So how much would I save, Jacob, on my summer air/con
power bills if I double glazed (which I won't). Figure on air/con being
'on' for a total of about 5 months a year [June - September plus bits and
pieces in other months.


  #15   Report Post  
Simon Gardner
 
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Default Putting a double glazed pane in an old frame

In article ,
(jacob) wrote:

Waste of money. If it's broken and needs replacing double glazing
still a waste of money - don't bother.


From the New Statesman 6 January 2003

It's all a lot of hot air
=========================

Resist double glazing salesmen, advises JEFF HOWELL.
They can't save us from global warming

Are you, in these midwinter bothered by double glazing
salesmen? They are annoying *******s at the best of times.
But they have become especially irritating since 1 April
2002, when they could start claiming that, as well as
fighting global warming and stopping old people dying from
hypothermia, they had the British government on their side.

April Fool's Day was an appropriate date to launch the
mishmash of convoluted reasoning that forms the new Part L1
of the Building Regulations for England and Wales, and which
decrees that henceforth all new windows shall be
double-glazed. The new rules include much genuflecting to
the Kyoto Protocol, which committed western governments
(though not the US, obviously) to reducing waste heat. Or
"carbon emissions", as we are now supposed to call it.

Other European countries have decided to crack down on
carbon emissions from power stations, factories and motor
vehicles, but the British government has decided that our
primary source of carbon emissions is poor people heating
their homes with one-bar electric fires, and that if they
would all just replace their windows with new double
glazing, then that should do the trick.

They reached this conclusion after much unselfish
committee-stage work by the British glass industry, which
helpfully suggested that a thermal insulation value of two
watts per square metre per degree centigrade would be about
right. And now that the new building regulations have been
unveiled, it must be gratifying for the glass-makers to find
that the only way to achieve this new insulation value is by
using sealed double-glazed units made with their own special
low-emissivity ("low-e") glass. And I am sure it is nothing
more than a coincidence that April saw the price of low-e
glass rise by 5 per cent, followed by a further 10 per cent
hike in September.

Low-e glass is very clever stuff. It has a metallic coating
that reflects approximately 25 per cent of escaping heat
back into the room. The downside is that the metallic
coating also reflects approximately 25 per cent of incoming
light back outside, so that the new windows appear much
darker than ordinary glass.

It is a testament to the enduring scientific ignorance of
the British public that they are consistently surprised by
this. After all, heat and light are but a few wavelengths
apart on the electromagnetic spectrum, and if you reflect
one, then you are sure as hell likely to reflect the other.
But the salesman didn't mention it, so the punters are
puzzled. It's all done with mirrors, you see.

When we say "double glazing", what we really mean is
"replacement windows". Most replacement windows are sold
over the phone by commission-paid salesmen, and are made
from PVC-U, or uPVC as it used to be called. The "U" stands
for "unplasticised", to distinguish it from plasticised PVC,
which is what raincoats are made out of. But though PVC-U is
not as bendy as raincoat material, it is still a bit bendy,
which is why the window frames are so chunky looking. They
have to be, to stop the things from flopping around when you
open them.

So the darkness inside homes fitted with replacement PVC-U
windows is also a function of at least one-quarter of the
window area being taken up with the framing material itself.
Beautiful 1930s houses with delicate timber fenestration are
having their windows replaced with PVC-U.

They look as though their front elevations have been redrawn
using a blunt pencil.

And despite their chunkiness, PVC-U window frames still have
to be reinforced internally with steel or aluminium alloy
bars. Which creates a bit of a problem when it comes to
reaching the aforementioned thermal insulation value. For,
contrary to popular perception, PVC is not a particularly
good insulator. Considerably less effective than wood, for
example. And when you poke a bit of metal down inside it, it
becomes even more likely to conduct heat out of the house;
which is why owners of new double glazing are often
surprised to find condensation forming on the plastic frames
of their new windows.

But the chief complaint of double glazed homeowners is not
about insulation, it is about internal misting. Sealed
glazed units are bound to mist up sooner or later, due to
the irrevocable forces of nature. The sealing material that
joins the two panes of glass has to be flexible, otherwise
the glass would break, and physics dictates that a flexible
seal will also be vapour-permeable. Sealed glazed units cope
with the constant seepage of moist air by incorporating a
desiccant within the perforated alloy spacer bars that run
around the perimeter. Eventually, the desiccant will become
saturated, and the double glazing will mist up. This is also
something that the salesmen never mention.

The timescale before the glazing mists up depends on the
quality of the installation. Dryglazed vented units in
German windows may last 30 years. Cheap back-street British
units stuck in with putty have been known to fail after
three months.

Double glazing won't save you any money in the long run. If
you take into account making the product, installing it,
disposing of the old windows . . . well, it's like nuclear
power; it's a net consumer of money and energy. There used
to be an advert on the telly, with dear old Ted Moult
saying: "You only fit double glazing once, so fit the best -
fit Everest." So how come Everest is now leafleting all its
customers, telling them they might wish to "upgrade" to the
new standards?

Jeff Howell is a bricklayer, and building columnist for the
Sunday Telegraph




  #16   Report Post  
The Natural Philosopher
 
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Default Putting a double glazed pane in an old frame

Simon Gardner wrote:

In article ,
"Mary Fisher" wrote:


Double glazing increases the comfort of a house, you can sit (as we do)
close to uncurtained windows on the coldest of days and still be
comfortable.


Actually, one of the things I like about windows is you can sit next to
them if you want to be a bit cooler but everyone else doesn't.



You can sit next to my SG windows wit the same result actually. Being
small in area and hermetically sealed, they are onot that cold.

DG is a bit of a con. Far more heat is lose through uninsulated walls and draughts.




OTOH Jacob's calculations are on heat loss and not including getting rid of
unwanted heat gain. So how much would I save, Jacob, on my summer air/con
power bills if I double glazed (which I won't). Figure on air/con being
'on' for a total of about 5 months a year [June - September plus bits and
pieces in other months.





  #17   Report Post  
jacob
 
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Default Putting a double glazed pane in an old frame

OTOH Jacob's calculations are on heat loss and not including getting rid of
unwanted heat gain. So how much would I save, Jacob, on my summer air/con
power bills if I double glazed (which I won't). Figure on air/con being
'on' for a total of about 5 months a year [June - September plus bits and
pieces in other months.


Dunno - you'll have to work it out for yourself!
Can't say I've ever suffered from unwanted heat gain in Britain. I'd
open the windows and generate a bit of through draught.
The french have the answer to summer heat - high ceilings, large
windows opening inwards with slatted shutters closed on the outside -
bliss, who needs air conditioning?

cheers

Jacob
  #18   Report Post  
Mary Fisher
 
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Default Putting a double glazed pane in an old frame


"jacob" wrote in message
om...
Dunno - you'll have to work it out for yourself!
Can't say I've ever suffered from unwanted heat gain in Britain. I'd
open the windows and generate a bit of through draught.
The french have the answer to summer heat - high ceilings, large
windows opening inwards with slatted shutters closed on the outside -
bliss, who needs air conditioning?


So why don't you live in france ?

Mary

cheers

Jacob



  #19   Report Post  
jacob
 
Posts: n/a
Default Putting a double glazed pane in an old frame

OTOH Jacob's calculations are on heat loss and not including getting rid of
unwanted heat gain. So how much would I save, Jacob, on my summer air/con
power bills if I double glazed (which I won't). Figure on air/con being
'on' for a total of about 5 months a year [June - September plus bits and
pieces in other months.


Come to think - summer heat gain would be based on difference between
reasonable room temp say 65F and high summer air temp say 85F - 20deg
F difference. Not a lot compared to winter frost, say - 5F; heat loss
based on temp difference of 70 deg F. Hence DG contribution summer
saving less than a 3rd of winter saving on any particular day with
these temperatures. It would depend on the frequency of high/low temps
and the efficiency of cooling compared to heating. I'd guess cooling
less efficient than heating but I don't know.
Opening windows a cheaper and more pleasant option.

cheers Jacob
  #21   Report Post  
jacob
 
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Default Putting a double glazed pane in an old frame

"Mary Fisher" wrote in message ...
"jacob" wrote in message
om...
Dunno - you'll have to work it out for yourself!
Can't say I've ever suffered from unwanted heat gain in Britain. I'd
open the windows and generate a bit of through draught.
The french have the answer to summer heat - high ceilings, large
windows opening inwards with slatted shutters closed on the outside -
bliss, who needs air conditioning?


So why don't you live in france ?

Mary


Good point. Employment the main prob I suppose. We go there a lot for
hols (cycle touring). People with holiday homes often seem pinned down
whereas we can go to any part of France. Best thing is to know people
with 2nd homes and go and visit them, rather than having ones own.

cheers

Jacob
  #22   Report Post  
Mary Fisher
 
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Default Putting a double glazed pane in an old frame


"jacob" wrote in message
om...
"Mary Fisher" wrote in message

...
"jacob" wrote in message
om...
Dunno - you'll have to work it out for yourself!
Can't say I've ever suffered from unwanted heat gain in Britain. I'd
open the windows and generate a bit of through draught.
The french have the answer to summer heat - high ceilings, large
windows opening inwards with slatted shutters closed on the outside -
bliss, who needs air conditioning?


So why don't you live in france ?

Mary


Good point. Employment the main prob I suppose. We go there a lot for
hols (cycle touring). People with holiday homes often seem pinned down
whereas we can go to any part of France. Best thing is to know people
with 2nd homes and go and visit them, rather than having ones own.


Or you could shell a bit out and make your windows oopen inwards and fix
slatted shutters on the outside then you'll have your own bliss.

I wonder how many deaths of French people that saved during last year's
torrid conditions ...


  #23   Report Post  
Niall
 
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Default Putting a double glazed pane in an old frame

On Sun, 18 Jan 2004 20:04:12 -0000, "Mary Fisher"
wrote:



We've double glazed our whole house by getting the glass company to make
factory sealed units to exactly the size we specified. That's thirty five (I
think) units. Spouse fitted them over a couple of years so the cost - which
was VERY low - wasn't felt at all.


We replace with these when a window gets broken. No problems with them
at all. (Wooden frames about 20 years old.)
An added advantage is when getting telesales calls from DG companies,
the determined ones who ask you whether you have replacement windows
quickly shut up and go away when you tell them you have fitted sealed
units to existing sound windows as they realise you are not going to
fall for their speil.

--
Niall
  #24   Report Post  
jacob
 
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Just spotted this in the grauniad

cheers

Jacob

Scientists' survival tip: go with the flow

Tim Radford, science editor
Thursday August 7, 2003
The Guardian

British scientists have just issued a hot tip for survival when the
fan has broken down and the thermometer is up. It saves energy and
exploits everyday household technology.

Just open a window, says Gary Hunt, who leads research at Imperial
College London into the fluid mechanics of natural ventilation. It
helps to have a sash window in the right place and at the right
height.

"Many of us have forgotten how to correctly use the sash windows so
carefully installed by the Edwardians and Victorians to maximise
airflow," he said. "If used correctly it is possible to significantly
improve comfort in the office or at home without using air
conditioning units that place high demands on energy and increase
carbon dioxide emissions."

He used a small laboratory model to simulate the average home as a
hothouse and keep track of cool airflow through rooms and buildings.
It is best to have your sash window open equally top and bottom. That
way cooler air flows into the room through the lower opening and
flushes the warm air out through the top.

If the windows are too small, or badly placed, however, hot air is
trapped at ceiling level and extends down to make the inhabitants
unpleasantly hot and muggy.

"Our research shows a good strategy is to leave sash windows in the
mid-position overnight - providing it is safe to do so," he says.

"The cool external air flushes the warm air of of the room and also
cools the walls, floor and ceiling. The cool walls absorb the heat the
following day and prevent the internal from temperatures rising as
high."
  #25   Report Post  
jacob
 
Posts: n/a
Default Putting a double glazed pane in an old frame

Also just noticed this below from Simon Gardner - brilliant, just what
I've been saying all along. Must remember to sort long threads by date
or you can miss interesting bits. Also must take out sub to New
Statesman - used to years ago but lost the habit..

cheers

Jacob

(Simon Gardner) wrote in message ...
In article ,
(jacob) wrote:

Waste of money. If it's broken and needs replacing double glazing
still a waste of money - don't bother.


From the New Statesman 6 January 2003

It's all a lot of hot air
=========================

Resist double glazing salesmen, advises JEFF HOWELL.
They can't save us from global warming

Are you, in these midwinter bothered by double glazing
salesmen? They are annoying *******s at the best of times.
But they have become especially irritating since 1 April
2002, when they could start claiming that, as well as
fighting global warming and stopping old people dying from
hypothermia, they had the British government on their side.

April Fool's Day was an appropriate date to launch the
mishmash of convoluted reasoning that forms the new Part L1
of the Building Regulations for England and Wales, and which
decrees that henceforth all new windows shall be
double-glazed. The new rules include much genuflecting to
the Kyoto Protocol, which committed western governments
(though not the US, obviously) to reducing waste heat. Or
"carbon emissions", as we are now supposed to call it.

Other European countries have decided to crack down on
carbon emissions from power stations, factories and motor
vehicles, but the British government has decided that our
primary source of carbon emissions is poor people heating
their homes with one-bar electric fires, and that if they
would all just replace their windows with new double
glazing, then that should do the trick.

They reached this conclusion after much unselfish
committee-stage work by the British glass industry, which
helpfully suggested that a thermal insulation value of two
watts per square metre per degree centigrade would be about
right. And now that the new building regulations have been
unveiled, it must be gratifying for the glass-makers to find
that the only way to achieve this new insulation value is by
using sealed double-glazed units made with their own special
low-emissivity ("low-e") glass. And I am sure it is nothing
more than a coincidence that April saw the price of low-e
glass rise by 5 per cent, followed by a further 10 per cent
hike in September.

Low-e glass is very clever stuff. It has a metallic coating
that reflects approximately 25 per cent of escaping heat
back into the room. The downside is that the metallic
coating also reflects approximately 25 per cent of incoming
light back outside, so that the new windows appear much
darker than ordinary glass.

It is a testament to the enduring scientific ignorance of
the British public that they are consistently surprised by
this. After all, heat and light are but a few wavelengths
apart on the electromagnetic spectrum, and if you reflect
one, then you are sure as hell likely to reflect the other.
But the salesman didn't mention it, so the punters are
puzzled. It's all done with mirrors, you see.

When we say "double glazing", what we really mean is
"replacement windows". Most replacement windows are sold
over the phone by commission-paid salesmen, and are made
from PVC-U, or uPVC as it used to be called. The "U" stands
for "unplasticised", to distinguish it from plasticised PVC,
which is what raincoats are made out of. But though PVC-U is
not as bendy as raincoat material, it is still a bit bendy,
which is why the window frames are so chunky looking. They
have to be, to stop the things from flopping around when you
open them.

So the darkness inside homes fitted with replacement PVC-U
windows is also a function of at least one-quarter of the
window area being taken up with the framing material itself.
Beautiful 1930s houses with delicate timber fenestration are
having their windows replaced with PVC-U.

They look as though their front elevations have been redrawn
using a blunt pencil.

And despite their chunkiness, PVC-U window frames still have
to be reinforced internally with steel or aluminium alloy
bars. Which creates a bit of a problem when it comes to
reaching the aforementioned thermal insulation value. For,
contrary to popular perception, PVC is not a particularly
good insulator. Considerably less effective than wood, for
example. And when you poke a bit of metal down inside it, it
becomes even more likely to conduct heat out of the house;
which is why owners of new double glazing are often
surprised to find condensation forming on the plastic frames
of their new windows.

But the chief complaint of double glazed homeowners is not
about insulation, it is about internal misting. Sealed
glazed units are bound to mist up sooner or later, due to
the irrevocable forces of nature. The sealing material that
joins the two panes of glass has to be flexible, otherwise
the glass would break, and physics dictates that a flexible
seal will also be vapour-permeable. Sealed glazed units cope
with the constant seepage of moist air by incorporating a
desiccant within the perforated alloy spacer bars that run
around the perimeter. Eventually, the desiccant will become
saturated, and the double glazing will mist up. This is also
something that the salesmen never mention.

The timescale before the glazing mists up depends on the
quality of the installation. Dryglazed vented units in
German windows may last 30 years. Cheap back-street British
units stuck in with putty have been known to fail after
three months.

Double glazing won't save you any money in the long run. If
you take into account making the product, installing it,
disposing of the old windows . . . well, it's like nuclear
power; it's a net consumer of money and energy. There used
to be an advert on the telly, with dear old Ted Moult
saying: "You only fit double glazing once, so fit the best -
fit Everest." So how come Everest is now leafleting all its
customers, telling them they might wish to "upgrade" to the
new standards?

Jeff Howell is a bricklayer, and building columnist for the
Sunday Telegraph



  #29   Report Post  
jacob
 
Posts: n/a
Default Putting a double glazed pane in an old frame

"The cool external air flushes the warm air of of the room and also
cools the walls, floor and ceiling. The cool walls absorb the heat the
following day and prevent the internal from temperatures rising as
high."


This is completely pointless, however, when the external air is not cool -
as it wasn't last August, or the August before that or the August before
that.


Another afterthought - if Simon doesn't think opening windows has any
benefit in hot weather does this mean that he has spent the last 3
very hot Augusts with windows closed?
If so he would have been extremely uncomfortable. This could account
for his enthusiasm for air conditioning, which most of us can do
without, having discovered the benefits of opening windows in hot
weather.
Conversely I wonder if he opens all his windows in winter and turns up
the central heating?

cheers

Jacob
  #30   Report Post  
Simon Gardner
 
Posts: n/a
Default Putting a double glazed pane in an old frame

In article ,
(jacob) wrote:

"The cool external air flushes the warm air of of the room and also
cools the walls, floor and ceiling. The cool walls absorb the heat the
following day and prevent the internal from temperatures rising as
high."

This is completely pointless, however, when the external air is not cool -
as it wasn't last August, or the August before that or the August before
that.


Another afterthought - if Simon doesn't think opening windows has any
benefit in hot weather does this mean that he has spent the last 3
very hot Augusts with windows closed?


Yup. I've got aircon. The inside of the house never goes above 21.


If so he would have been extremely uncomfortable.


No. I've got aircon. I've been exceedingly comfortable, thanks, as long as
I don't go outside.

This could account
for his enthusiasm for air conditioning, which most of us can do
without,


You are an idiot.

having discovered the benefits of opening windows in hot
weather.


It doesn't work in August. It only works earlier in the year and later. It
doesn't work in August on account of that big yellow thing in the sky and
the fact that daytime temps are over 31 and night time temps over 24.

Conversely I wonder if he opens all his windows in winter and turns up
the central heating?


Why do you think this is "conversely". Its just as stupid as opening them
in August. In winter it would be too cold and in August too hot.

Why is this concept too hard for you to understand?




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