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My New Replacement Windows Have Engines?

replacement window balance systems

My New Replacement Windows Have Engines?

replacement window balance systems

When we share with Charleston, Savannah, Hilton Head and other Low Country area homeowners that their new replacement windows have engines, they look at us kind of funny.

The engine on a Sunrise replacement window is also called the balance system, and it assists in raising and lowering the window, and also plays a part in dropping in a sashed window for easy cleaning.

For todays' continuation of our trip through the eight critical areas when it comes to replacement windows, we want to talk about the different types of engines you'll find in new home windows.​

Types of Balance Systems for Replacement Windows

In new home windows today, there are basically three different types of engines (balance systems)...​

  • Spiral Balance
  • Constant Force Balance
  • Self Tensioning Block and Tackle Balance

As with any other engine, there are differences based on changes in engineering, different parts to accomplish the same goals, maintenance issues and how long they last...Let's take a look at each of the three, using these comparison points.

replacement window spiral balance system

Spiral Balance System

  • Oldest
  • ​5000 cycle life
  • Spring failures and loss of oil
replacement window constant force balance system

Constant Force Balance System

  • On most windows today
  • 12,000 cycles
  • All the same size
self tensioning block and tackle balance system

Block and Tackle Balance System

  • High end name brand products
  • 48,000 cycles
  • Different sizes

The Pros and Cons of Each Balance System for Replacement Windows

As you begin to look at the pros and cons of each replacement window balance system, similarities to the way you might evaluate different vehicle engines exist. Think evolution of technology, longevity (mileage) and overall cost.

The spiral balance system, being the oldest, represents the original automobile engines. They were the new, shiny objects that were revolutionary for their time. Unfortunately, their limited cycle life (a cycle being defined as raising and lowering the windows once a day), and failure rates (have you ever unlocked your window and it started opening on its own?!) meant it was time to evolve the technology.

Paralleling the growth in the automobile industry, as the window industry began its rapid growth, vinyl replacement windows became far and away the consumer choice for new home windows. As a result of the issues caused by failing spiral balance systems, engineers looked for a better way and the constant force balance was born.

The constant force balance looks similar to the inside of a tape measure. 95% plus of vinyl window manufacturers today use this balance system for the engine of their rep​lacement window products, and for good reason. These balance systems have been engineered to last over twice as long as their spiral balance counterparts. All of these are typically the same size, helping the manufacturer minimize costs through easier inventory control.

Unfortunately, this "same size" benefit can be a restraint also, as larger sized windows need more of these to make the window operate correctly, effectively limiting how much you can open your window. There are issues as well in terms of replacement. These balances are encapsulated in an area that has a smaller opening that the system itself, making it difficult to remove and replace them ​during any instances of failure.

The self tensioning, block and tackle system is used by many of the most well know window manufacturing names, like Andersen and Pella. Why, because it's the best. This ain't your grandads old block and tackle system.

Block and tackle is a system that dates back to early days, when a window used a weight and kite string to operate. Of course, when that kite string inevitably dry-rotted you had a big problem.

Todays block and tackle is designed with a heavy duty, stainless steel spring that mimics a chain fall. In the "old days" when you took out an engine from a car it took muscle power; four or five guys ​pulling a rope thrown over a rafter attached to the engine.  A chain fall uses a pulley system spreads weight and pressure around so that even a 12 year old could pull out an engine.

Instead of kite string, the self tensioning block and tackle system uses a Kevlar impregnated, polyester cord. This is the same cord that you'll find in parachutes.​

Even though the self tensioning block and tackle balance system is engineered to last four times as long as the constant force, due to all the parts involved, as well as inventory costs associated with having to carry different sizes leads to a much higher cost.

Our replacement window partner, Sunrise Windows, has chosen to spend the extra money and use this process as the balance system for our Low Country replacement window customers. Call us today and let us show you, up close, how this engine is the best one for your "new car."

Still Researching? We Get It...
Before buying new replacement windows for your home, download and read our ebook "How To Buy Vinyl Replacement Windows" Including a checklist to use when talking to a contractor about replacement windows.

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