Driving Miss Window

replacement window balances engineDid you know that your windows have an engine? They’re called balance systems. Today we’ll go under the hood to take a peek at the different types of replacement window balances and their effects on performance.

Of all the eight critical areas when it comes to choosing new replacement windows for your home, this is the one that probably gets the least amount of attention. That’s unfortunate, because these “engines” can have an effect on the long-term operability of your windows.

What Do Replacement Window Balances Do

Single and double hung replacement windows, as well as sliding windows, have sashes that move; for hung windows, up and down, and side to side for sliding windows.

replacement window balances systemThat sash movement is important, as it allows you to save money on power bills in the spring and fall by allowing some fresh air in, as well as provide a way out of your home in the event that need to get out of a room quickly.

Replacement window balance systems control not only how well the sashes move, but also whether they move at all, and how much they move.

Just like the engine on your car, the balance system is not visible by just looking at the window. They reside within the tracks that the sash slides on, like you’ll see here.

How Do Replacement Window Balances Work

replacement window balances shoesIn conjunction with a “shoe” (pictured here), the balance system controls the movement up and down, or side to side, of the sash. Different types of replacement window balances can affect the ease of movement, as well as how far the sash can move.

Choosing the Right Replacement Window Balance System

When it comes to making the right balance system choice for your new home windows, there are three main things to pay attention to: ease of operation, ease of repair and/or replacement, and engineered life expectancy.

The three most commonly used replacement window balance systems are the spiral balance, the coil balance and the self tensioning block and tackle balance.

Spiral Balance

Spiral balances were initially very popular in wood and metal windows and migrated to some of the earliest replacement, thermal pane, window systems.

  • replacment window spiral balanceOperation—As you can see, this system works off of a spiraling piece of metal that slides in and out of a cylindrical tube. Inside there is an oiled spring. If you ever opened a window and heard a loud springing noise, or the window opened on its own, you’ve experienced how this system operates.
  • Repair/Replace—At the end of its engineered life, this system can be repaired using a special tool. The cost for repair is around $50 per window.
  • Life Expectancy—As the oldest (technologically) of all the replacement window balance systems, you can expect that this particular system has the shortest life expectancy of all. This is measured as an expression of the number of cycles a system is engineered to last (a “cycle” is raising and lowering a sash one time). Replacement window spiral balances are engineered to last about 5000 cycles.

Constant Force Coil Balance

The coil balance system is the engine for well over 90% of the vinyl replacement windows on the marketplace today.

  • Operation—When asked, most people look at a coil balance and say that it looks like what replacment window coil balancethey’d think the inside of a tape measure would look like. Like a tape measure it uncoils as the sash is pushed up or to the side, and recoils to the return position. Each one of these is the same size, so, in larger window units, multiple coils must be used as in the image below. One of the potential effects of that is a limitation to how far the sash can move.
  • Repair/Replace—Unlike the spiral balance, and the self-tensioning block and tackle, coil balances reside inside of the shoe (as illustrated here), instead of being attached to the window itself. This becomes an issue if a coil balance needs to be replaced. As you can see, the shoe is wider than the gap, and must be removed by heating up the vinyl, removing  the shoe with the old balances, then reheating the vinyl and sliding the new shoe and balances back in. The other possibility is that the sliding track must be cut to allow removal and replacement. Either of these choices are cause for concern for most homeowners.
  • Life Expectancy—Due to its widespread use, you’d anticipate that the coil balance system has been engineered to last longer than its spiral cousin, and you’d be correct. At 12,000 engineered cycles the replacement window coil balance lasts over twice as long as the spiral system.

Self-Tensioning Block and Tackle

This balance system design is the method of choice for all of the best known, name brand window systems on the market today.

  • replacement window self tensioning block and tackle balanceOperation—Unlike your grandfather’s original block and tackle system which basically used a combination of iron weights and kite string, todays system combines a heavy duty, stainless steel spring, an pulley system similar to a “chain fall” that’s used to pull engines out of automobiles and parachute cord to move the windows sashes.
  • Repair/Replace—As this particular system attaches to the interior assembly of the window, and clips into the shoe, in the rare occurrences where one needs to be replaced, it’s the most easily interchangeable balance system of all.
  • Life Expectancy—At 48,000 cycles, the self-tensioning block and tackle balance system is designed to allow you to raise and lower your window sash once a day for the next 130 years.

Which Replacement Window Balance System Is The Right One

Certainly, as we, and other manufacturers, try to answer this question, we have to think through several things.

  • Cost—Individual component cost figures into overall product cost, right? One of the reasons that the coil balance finds such widespread use is that it is not only relatively inexpensive, but, because all coil balances are the same size, it helps a manufacturer with inventory considerations.
  • Warranty—No matter how good a warranty sounds, one of the key long term concerns for the manufacturer is hardware operation, as these are the parts that get the most use. If you give yourself an out with hardware by using the words “…against manufacturer defect” you give yourself some wiggle room with the level of quality necessary in your balance system.
  • Homeowner—Understanding and maximizing user experience should be the ultimate driving force in this decision making process.

For us, this has always been a pretty straightforward choice. Even though the self-tensioning block and tackle is the most expensive of the three, and even with the inventory considerations because of the different sizes based on the size of the window, cost hasn’t been a driving factor concerning balance systems here at Sunrise.

For us, it’s always been about user experience…because of the construction of the self-tensioning block and tackle you can be assured of smooth,easy operation, no matter which side of the window that you are standing on.

The other part of user experience is about longevity. Based on cycle testing, I think you can see why we warrant our replacement window balances on a lifetime basis “…against breaking, cracking , or otherwise failing.”

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