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By Steve Jordan
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An "X-ray" view of a spring
balance shows the coiled steel spring that
provides the counterbalancing force.
Photo Courtesy of Steve Jordan
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Cords, weights, and pulleys have been holding sash open for well over 150 years and are still at work in thousands of old-house windows. All the while, manufacturers have tried to match their effectiveness with systems promoted as smaller, simpler, or cheaper, but only one came close: the sash-spring counterbalance. Often installed as original equipment, spring balances are worth knowing about because these clever devices are not only historically appropriate for retrofitting old windows, but they're also practical for solving some common, modern old-house problems.
The Source of Springs
In the 1890s, as the Industrial Revolution was reaching its peak, technological achievement became both the essence of the American spirit and good business. Everyone wanted to patent a better mousetrap, and there was a steady stream of novel inventions seeking to improve every industry, including building construction. The need to
conveniently control double-hung sash had spawned many gizmos, from cams and ratchets to tension bars and spring pins, but the spring balance, which first appeared in the 1880s, was something different.
Also called a tape or clockspring balance, the spring balance is a metal tape, permanently greased and wound on a wheel. This wheel in turn is mounted on a coiled, high-carbon steel spring inside a metal case, similar in construction to a small carpenter's measuring tape. Just as cast iron or lead weights were matched, pound for pound, to each sash, spring balances were manufactured and sold in various sizes that would offset the weight of a particular sash. However, instead of running cotton rope from sash to weights over a pulley, the spring balance connected to the sash by a metal tape that stretched up the channel into the spring case that took the place of a pulley. Visually, there was little difference.
At the turn of the 20th century, Frank Kidder's pioneering guide Building Construction (1913) listed several reasons for choosing spring counterbalances. The primary advantage was that the spring balance required less space than weight-and-pulley systems, which had to leave several inches of room for weight pockets on either side of the window. This was especially important on bay windows (or the increasingly popular banks of windows) where the mullion space between sashes was limited. Spring balances were also invaluable for plank-frame houses, where the absence of wall framing made weight pockets impossible, and in solid brick walls, where spring balances alleviated the need to build openings any wider than necessary for the window proper. By 1894, the Sensible Sash Balance of Groton, New York, was one of several spring balances being advertised. A decade later Kidder mentioned two sources for spring balances: Pullman Manufacturing Company and Caldwell Manufacturing Company, both of Rochester, New York. Though Caldwell balances are no longer sold, Pullman spring balances have been on the market since 1886 and are still manufactured today.
Today's construction industry usually considers the spring balance, like the weight-and-pulley system, a hardware dinosaur, a window curiosity. In building restoration, however, the compactness and availability of the spring balance makes it eminently practical for upgrading historic windows that have obsolete balance systems or no balance systems at all. Because the tape case is self-contained, a spring balance can even help improve the environmental efficiency of a window by blocking cold air that sometimes finds its way through the openings in a sash- cord pulley.
Springs in Action
Installing spring balances is simple, provided you follow the correct steps. First, you must determine the weight of each sash. Carefully remove one or both of the window stops (see below), then gently secure any existing balance-system ropes or tapes. Afterwards, carefully angle the sash out of the window. If the sash is held by ropes, pull the ropes from the stile pockets, noting that they might be held in place with a tack or screw. If the sash is held by spring-balance tapes, remove the tape from the stile pocket or disconnect it from the securing bracket.
Place the sash on a bathroom scale and note the weight; reading to the nearest pound is good enough. Next, order a pair of spring balances that correspond to the weight of the window sash. For example, if your sash weighs 14 pounds, each of the two new balances must be sized to 7 pounds. Under spec'ing the balances can result in a sash that is hard to lift and won't stay open; if they're over spec'd, the sash won't stay shut.
If you are replacing an existing spring balance, remove the screws securing the balance, gently cut the paint seal around the faceplate with a sharp razor knife, then pry out the balance using a screwdriver or awl. The new spring balance faceplate will probably not match the original, so place the new balance in the old hole and transfer the outline of the new faceplate with a pencil. Next, mortise out shallow recesses for the half-circle ends of the plate by carefully boring with a spade wood bit within the pencil line. Finish up other areas with a chisel, then insert the balance in the hole and attach it with the screws. The balance faceplate should not stand proud of the sash channel, and it should allow the sash window to slide over the balance.
If you are installing a spring balance in place of a rope pulley, remove the old pulley and enlarge the pocket to accept the new balance using a sharp wood chisel. Mortise for the faceplate as already described. If no pocket exists, create a new pocket using an appropriately sized spade bit and wood chisel, being careful to avoid hitting any pipes or wires that might hide behind the window frame.
The tape should connect to the sash about halfway down the stile and never so high that the tape hook rises above the balance when the window is fully open. To install the tape hook, mortise an appropriate hole in the side of the sash stile 1/2? or so deep with a wood chisel. Bevel the mortise at the top where the tape enters to prevent it from creasing or bulging.
To connect a tape to the sash, first pull an ample amount of tape out of the balance to prevent crimping. This works best with two people, but if you are alone carefully wedge a screwdriver in the balance or gently grip the tape with locking pliers to brake the spring tension. Then place the bail on the end of the tape in the hook and gently bend the flange down so it secures the tape and clears the spring balance. Release the tapes, ensuring that they lie flat against the channel, and reinsert the sash in the window. Before reattaching the sash stops, slide the sash up and down to confirm that it glides smoothly without jamming, then reinstall the stops with screws or small finishing nails.
Removing Stops
When sash stops are covered with multiple coats of paint or secured with numerous or oversized nails they can be difficult to remove, but some simple methods and tools can help. First, remove any curtain or shade hardware attached to the top of the stop. Next gently score the paint at the junction of the stop and the jamb or casing with a sharp razor knife. Do not force the knife because it is easy to run off track and cut the window casing. Instead, make several light passes. Once the paint is scored, pull the razor knife down the score to break the paint seal. If the stops are secured with screws, first remove any paint from the screw slots and then remove the screws.
Everyone uses pry bars to remove window stops, but some are better than others. The best pry bars for window works are very thin with a long taper to the sharp end, and two work better than one. Equally valuable are one or more minibars (1/2" or so wide) and a pair of wide-blade putty knives. Using the thin, sharp end, insert the bar between the stop and jamb about 12" up from the stool. Using putty knives can shield the wood from pry marks. Gently try to pull the stop out about 1/8" to 1/4". Next, slip the other bar behind the first and move up and down the stop, pulling it away from the jamb slowly. If the stop seems stuck at the top and bottom, it may be because the original carpenter got a great fit by cutting the stop slightly long, then bowing it in the middle as he installed it. Or he may have mitered or mortised the ends into the window frame. If this is the case, after you have removed all fasteners you too will have to bow the stop the in the middle to pull it out. If you break your sash stop, all is not lost. Most styles are still available at lumber companies.
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