When a sash opens, the weight counterbalances with a weight inside the window frame. This weight connects to the opened sash through a cord that runs over a pulley at the top of the window frame. This method is a simple cord, weight, and pulley mechanism.
Full Answer
How does a window balance system work?
The basic principle of a weight and pulley balance system is a simple one: A vertically sliding sash is attached to and suspended by lengths of cord or chain. Each cord or chain passes over a pulley mortised into the window jamb near the top of the opening.
Why do double hung windows need a weight and pulley balance system?
In conclusion, it is useful to remember the reasons which contribute toward making the weight and pulley balance system a permanent and reliable mechanical system for the operation of double-hung wood windows: The inherent longevity of the components and the materials from which they are made.
What size counterweight do I need for a 1 3/4 window?
Generally speaking, a window with 1 3/4" thick sash will use 1 3/4" round or square counterweights. If 1 3/4" weights were used on a window with 1 3/8" thick sash, the weights would collide during their vertical travel. So the maximum cross-section of sash weights is determined by the sash thickness.
What are the characteristics of a heavy window?
Width: Windows which are wide in proportion to their height will be heavy in proportion to their height. A counterweight for a short, wide window must be heavy in proportion to its length because the vertical space available for the travel of the weight is limited.
How does a window weight work?
0:323:15How Do Window Weights Work? - YouTubeYouTubeStart of suggested clipEnd of suggested clipSo basically there's a roller. Right here let these roll on and these are just a counterweight. SoMoreSo basically there's a roller. Right here let these roll on and these are just a counterweight. So when pull the window up the weight goes down and holds the sash up. And it makes it nice and easy.
How do you install window weights?
1:375:31How to Repair Damaged Window Sash Cords | Ask This Old HouseYouTubeStart of suggested clipEnd of suggested clipThere's the other one. All right okay what i'm going to use to replace your sash cord is this cottonMoreThere's the other one. All right okay what i'm going to use to replace your sash cord is this cotton. Line what i want to try to do is push it down the pulley hole.
How does a window pulley work?
The basic principle of a weight and pulley balance system is a simple one: A vertically sliding sash is attached to and suspended by lengths of cord or chain. Each cord or chain passes over a pulley mortised into the window jamb near the top of the opening.
What are old windows with weights called?
Windows operated by weight and chain, or sometimes called weight and pulley, have a chain (or cotton cord) that connects the sash to a weight that is concealed in the wall next to the window.
How do you fix old windows that won't stay up?
The balance is what makes the window stay open. So, remove the tilt latches on top of the bottom sash and tilt it until it is horizontal. Now, you'll want to tilt your lower sash outward so you can realign the bottom of your window with the balance shoe, which helps it stay up.
Are old window weights lead?
Traditional sash windows are balanced by sash weights which hang in the boxes at the side of the window. Traditionally the weights were made out of lead but in the Victorian era cast iron became a more popular choice as it was easier to get hold of and cheaper.
Why do windows have weights?
Window weights are common in double-hung windows. Window weights are lead weights that counterbalance the weight of a window sash - the movable part of the window - in older houses.
When did they start using window weights?
In the early 18th century a system of pulleys, ropes and weights gradually became standardised in the design of the overall window. This pulley system enabled the weight of the sashes to be balanced, making it easier to open.
Why do window regulators fail?
The window regulator can overheat from excessive use and stress over time, which can lead to a complete failure of the regulator. If a motor starts to overheat, the best practice would be to let it cool down before trying to use it again. Freezing temperatures can cause a window to disconnect from a window regulator.
How do you access weights on a sash window?
Grab the sash cord just outside the pulley and pull it out all the way. This will mark where the top of the pocket cover needs to be cut. On an intact cord, with the weight resting at the bottom of the pocket, grab the cord just outside the pulley.
Do all sash windows have weights?
Traditionally, all sliding sash windows were operated by cast iron weights. A sash box of 98mm is built into each side of the window, which houses the weights. This is then attached to a piece of sash cord, which travels over a pulley in the top corners of the window and attaches to the sash that will be sliding.
How do you insulate windows with sash weights?
0:031:34How to Insulate Window Weight Pockets | This Old House - YouTubeYouTubeStart of suggested clipEnd of suggested clipI've seen people go out and buy fiberglass bat insulation cut it in a strip that would roughly fitMoreI've seen people go out and buy fiberglass bat insulation cut it in a strip that would roughly fit into that weight pocket take a stick.
Why do windows have weights?
Window weights are common in double-hung windows. Window weights are lead weights that counterbalance the weight of a window sash - the movable part of the window - in older houses.
How do you replace spring balance sash weights?
1:417:10How to Replace a Window Sash Spring Balancer | This Old HouseYouTubeStart of suggested clipEnd of suggested clipI can simply remove this lower half of the side jam by flexing it or bending it out of the open.MoreI can simply remove this lower half of the side jam by flexing it or bending it out of the open. Okay now I need to lower the window. So I can pull it out of the open. With the bottom sash removed.
How do you install window inserts?
0:194:30Installing Your Indow Window Inserts - YouTubeYouTubeStart of suggested clipEnd of suggested clipWork your way up the sides gently pressing the insert into the frame. Then press the middle of theMoreWork your way up the sides gently pressing the insert into the frame. Then press the middle of the top edge into the window frame working your way out to the corners.
How do you tell if a window is installed correctly?
Difficulty Opening and Closing If a window was correctly installed, it should open and close fully and smoothly without any sticking. If your window sticks so much you have to force it to move or it doesn't reach the frame when you try to close it, you have a problem.
What are Window Weights?
Window weights are often made of lead and are weights that counterbalance the weight of the window sash to allow the window to move up and down smoothly. Depending on the age of your window, the system it uses will function differently. For example, in new hung windows, a modern counterbalance system is used. Old houses with old windows will utilize either a weight and pulley system inside the sash or a tape sash.
How much weight do you need for a window sash?
A good rule of thumb is that the weight of a typical window sash is 22 pounds and thus will need two counterweights weighing 11 pounds.
What is the difference between a double hung window and a single hung window?
The primary difference between a double hung window weight and a single hung window weight is that the double hung will have twice as many. This counteraction on both of the windows allows both of the window panels to slide. It involves more moving parts and will weigh slightly more due to one additional sliding weight. A single hung window only has one panel that moves and therefore only one window weight in each jamb.
What is a sash in a window?
A sash is attached to lengths of cord or a chain in the pulley system, depending on the pulley's material. These pass over a pulley that is mortised into the window jamb near the top of the opening.
How to calculate sash weight?
First, you need the total weight of the wood, glass, and hardware. Then you can figure out the weight of the two counterweights. The combined weight of the two should add up to the weight of the entire sash.
What is a window balance?
A window balance (sometimes called a sash balance, window spring, or window "balancer") is a somewhat hidden window component sitting inside the window frame. Window balances are only found in double-hung or single windows and counterbalance the weight of the sash assisting you with opening and closing your windows. Window balances are found in both residential and commercial windows. There are many different styles, types, and sizes of window balances, so finding the correct replacement can be tricky and at times frustrating continue reading to learn more about specific types of window balances and how they function.
How do weights work on a sash?
The weights are connected to ropes or chains and travel up and down as the sash is raised or lowered . The most common problem with this type or balance system is that the ropes will fray and break over time. The most common solution to this problem is to simply replace the chains.
What is a coil spring window balance?
Coil spring window balances are a type of constant force window balance. These balances work by using stainless steel, coiled spring as a counterbalance. This type of balance system is designed to be more durable and quieter than other balance systems. There are several parts to a coil spring balance system: the coil, the balance spring cover, ...
Why are pulleys grouped?
The pulleys are grouped as the “block” to reduce the load the homeowner feels. In addition, as the cord (or “tackle”) is pulled by the movement of the sash it stretches or compresses the springs, which are weighted to match the sash weight. The pulleys and springs assist with opening and closing the window.
How does an inverted block and tackle balance work?
Inverted block and tackle balances function similar to standard block and tackle balances except that the string comes out of the top of the balance instead of the bottom. These tilt balances work in conjunction with a T-lock shoe to allow your window to tilt inwards. If you need to replace your inverted block and tackle window balance just take a look at your stamp, the length of the metal channel, and the weight of your sash to find the correct replacement.
What weights are used on a window?
Generally speaking, a window with 1 3/4" thick sash will use 1 3/4" round or square counterweights. If 1 3/4" weights were used on a window with 1 3/8" thick sa sh, the weights would collide during their vertical travel. So the maximum cross-section of sash weights is determined by the sash thickness.
Why are windows heavy in proportion to their height?
A counterweight for a short, wide window must be heavy in proportion to its length because the vertical space available for the travel of the weight is limited.
What weight must match the weight of the glazed sash to which it is attached?
The combined weight of the counterweights must match the full weight of the glazed sash to which it is attached.
How does a pulley balance work?
The basic principle of a weight and pulley balance system is a simple one: A vertically sliding sash is attached to and suspended by lengths of cord or chain. Each cord or chain passes over a pulley mortised into the window jamb near the top of the opening. The opposite end of each cord or chain is attached to an iron, steel or lead counterweight weighing one-half the weight of the sash it is balancing. The counterweights are located within a concealed space or weight pocket. An accurate and well thought out design will result in sash which require little or no effort to operate and which will remain open or closed as desired.
How to calculate sash weight?
The best and most accurate way to calculate sash weight is to weigh the completed and glazed sash. For design purposes, estimates can be made based on the approximate weight of wood, glass, and hardware. The total weight of the two sash counterweights should equal the weight of the sash being balanced. The amount of operational friction in the sliding sash will determine the allowable margin of error in sizing the counterweights. The operational friction is largely a function weatherstripping.
What is weight and pulley balance?
The weight and pulley balance system for double-hung windows was, for many years, the standard in wood window construction. The inherent dependability of this system is once again bringing it into favor with quality-minded architects, builders and window fabricators. The purpose of this article is to examine some of the factors affecting the specification and design of weight and pulley balance systems for today's windows.
How thick is a double hung window?
Generally speaking, a window with 1 3/4" thick sash will use 1 3/4" round or square counterweights.