Balance Systems for Sash Windows
For a vertical sliding sash to stay in an open position a counter-balance is required. Let’s take a look at the options that have been developed.
TRADITIONAL WEIGHT AND CORD
The traditional box sash window uses a steel weight, attached to a cord, passed over a pulley and fixed to the glazed sash frame. The weights are not visible as they are suspended within the window frame. Any increase in weight, such as changing the glass, requires the weights to be re-balanced with lead weights.
- The original and still the best system -when correctly set-up.
- The momentum of the weights allows the sash to glide.
- Time proven, simple system.
SPIRAL & SPRING BALANCE
Invented in America these balances were introduced in the 1930’s, but their popularity really took off after the war. Spring balances offered a cheaper way to manufacture vertical sliding sash windows; not a better way. There are several variations of these balances but they all utilise a spring to offset the weight of the sash. The windows do not glide like a weighted sash; the spring simply stops the sash from dropping. Originally the spring was encased in a metal sheath but for many years now has come with a plastic one.
- Available in a wide range of sizes to suit any window.
- Time proven design
TAPE BALANCE (ACME Balance, Pullman Coils )
Another American invention that became popular after the war, also offered as a budget way to manufacture vertical sliding sash windows. Similar to an everyday retractable tape measure in design, the end of the tape connects to the bottom of the sash. As the window opens the tape retracts into the balance.
Larger frames require 1 pair of balances per sash (2 pairs = 4 balances per window) but on smaller windows it’s common to find only 1 balance and a guide wheel (2 balances &2 guides per window).
This system was deleted for many years but has recently been reintroduced into the USA. Uncommon in the UK where the spring balance was far more popular, but used extensively in the USA & Australia.
TILT AND SLIDE (JAMB LINERS)
A variation of the spring balance. This system was designed to offer the extra functionality of tilting inwards for supposed easier cleaning. In practise very few people make use of this option and in our experience they are often a disappointing balance system. Much of the weight is carried on flimsy plastic lugs that don’t last.