Balancing Options

Sash Balancing Options

Extant Ropes and Pulleys

Balancing your windows is important if you intend for them to operate. Proper balancing enables the sash to stay where you place it, throughout it's vertical travel. With balanced sash, you can throw away the sticks you've been using to prop open the window.

Obviously, one of the easiest ways to balance your windows is by utilizing the existing mechanisms available in the unit for that purpose. If your windows are like 95% of those we've run across, you have a balance system similar to the one on the left. 

It's beautiful in it's simplicity. Each sash is weighed (or the weight calculated) and the weight divided by two. Two "pig iron" ingots are provided that match those weights and attached to the sash by ropes or chains. The rope is passed over a pulley with the sash between the jamb sides and the weights in the balance cavity. With the proper length rope, the sash will travel the full length of the jamb and stay precisely where it is placed.

As with all other aspects of a repair/restore/preserve/improve project such as we're contemplating, there are pros and cons with every option. The advantages of the ropes and pulleys are that a) it's probably the easiest system to re-install after removing the sash and b) it's certainly the most original/historic. But, believe it or not, there are some downsides as well and it's debatable which are the most onerous. For one thing, many people who are undertaking a project of this scope do so with the intention of enhancing the thermal efficiency of the units and they feel the hollow balance cavity is a significant factor in heat loss and drafts (feel the wind blow through the pulley mortises?). That premise is itself is under debate amongst the professionals. 

If you feel it's important to insulate the balance cavities while reworking the windows, you will find that the original rope and pulley system is not conducive to that end. It can be done, albeit the solution is often too invasive for most home owners to attempt. It requires removing the interior casing and providing plastic tubing in which the weights can travel while the rest of the cavity is filled with insulation. Even after all that work there is a down side to to the weight in tube method - servicing the weights, ropes or chains. No one wants to have to remove the casing each time a rope or chain lets go.

Caldwell or Pullman Style Retractable Tape Balances

This style of balance has been used successfully for at least one hundred years. It is exactly like a tape measure in its function. We have found these still operational in a few window projects we've encountered. 

While they are a good product we must consider their pros and cons too. Pros: a) they are time tested and their functionality proven, b) they allow the balance cavity to be insulated and c) while they might not be original to your home, they were a true historic solution. The disadvantages are a) they are very expensive ($40 or more per set last time we checked), b) chances are good that existing pulley mortise will need to be enlarged and c) while they were in use in more ornate residential homes and commercial applications, they weren't commonly found in even moderately upscale homes, so they might be considered historically inappropriate for most users.

Constant Force Balances (CFBs)

These are our favorite balance method for several reasons. 

They too are of proven longevity. Since they are the balance of choice for many of the top of the line vinyl windows, there are literally millions in the field with a very low failure rate. With no moving parts beside the spring itself, they are rated at over 8000 cycles. CFBs are relatively inexpensive and easily mortised into the fabric (either into the sash with the tongue fastened to the jamb or vise-versa). The low profile and self-contained nature of the CFBs allow them to be hidden and the balance cavity filled. The only down side that we can see is that with them, the rope and pulley will be eliminated. It's a personal choice.