On 21 Feb, 11:39, (Roger Morton) wrote:
In ,

JimK wrote:

Any tips for dealing with sash weights to cope with extra weight
involved ?

I replaced the original cylindrical cast-iron weights with square lead
ones. Even with the double glazing I was able to use a slightly smaller
square section than the old cast-iron ones, and got rid of my
'clashing' problems at the same time.

http://www.ironmongerydirect.co.uk/P...nery_Hardware/
Vertical_Sash_Window_Hardware/795/Lead_Sash_Weights

--
Roger Morton

Why bother - sliding sashes always leak air so what''s the point of
DG. And anyway the heat loss through windows is always small in
comparison to the losses elsewhere so put your money and effort into
insulation where it will make a difference.

Rob

On Feb 21, 12:31 pm, robgraham wrote:
On 21 Feb, 11:39, (Roger Morton) wrote:



In ,

JimK wrote:

Any tips for dealing with sash weights to cope with extra weight
involved ?

I replaced the original cylindrical cast-iron weights with square lead
ones. Even with the double glazing I was able to use a slightly smaller
square section than the old cast-iron ones, and got rid of my
'clashing' problems at the same time.

http://www.ironmongerydirect.co.uk/P...nery_Hardware/
Vertical_Sash_Window_Hardware/795/Lead_Sash_Weights

--
Roger Morton

Why bother - sliding sashes always leak air so what''s the point of
DG. And anyway the heat loss through windows is always small in
comparison to the losses elsewhere so put your money and effort into
insulation where it will make a difference.

Rob

air leaks can AIUI be addressed as part of the rebuild with brush
strips, neoprene etc as per any opening window...

why bother? well all this for starters:-

"A single glazed window is sometimes referred to as a “Thermal Hole”.
It is considered that single glazed windows lose around one third or
33% of its heat in the average house. Payback time currently for high
insulation double glazed units is estimated at around 5 years
depending on cost of units and cost of energy. Future energy costs are
a major concern and insulation today is one of the most important
factors.

A recent commissioned report claims that since de-regulation of prices
in 2002 and from 2002 to 2005 average energy prices have risen by
about 60% more than inflation.

Convection is one of the major heat loses relative to a window which
is single glazed when it is cold outside and reasonable warm
inside.The warm internal air contacting the cold glass becomes
heavier, and drops downwards at a speed of around two metres per
second depending on relative temperatures, causing a perpetual
expensive heat loss and generally felt as a draught around the legs
and feet.
It is considered that a one degree increase in temperature in a room
at comfort level will increase energy costs by 2%.

Radiant transfer in respect of glass occurs when the warm internal air
contacts the cold single glass in a window and radiates or transfers
heat outwards through the glass at a constant rate.

Low emissivity glass used in the construction of a double glazed unit
reflects the long wave radiation or heat back into the room and
therefore reduces the radiant heat going out through the glass.

A window construction should use low conductive material and
particularly a double glazed unit which forms the largest area
normally in a window. All the material in a window will conduct heat
or cold depending on the conductivity of each material and a double
glazed unit has a major contribution to the insulation factor."

cheers
JimK