Frequently Asked Questions

I got 3 estimates from 3 window companies for my 3-flat. Two gave me low prices, and then came the hidden charges. Varco Windows delivered what was quoted with no extra or hidden charges. I got quality windows, installation and service at the price I expected. In the future, I'll call Varco.

– Tom, Chicago, IL

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Replacement Windows FAQs

You can find everything you ever wanted to know about our Replacement Windows right here! From learning what our windows are made of, to determining the best way to clean them, you'll find all of the answers you're looking for!

What is a vinyl replacement window?
A replacement window is a window designed to fit into an existing window opening. Vinyl replacement windows are made from 100% PVC. The combined strength of the multi-chambered frames and sashes and fusion-welded corners, make vinyl windows one of the most reliable and energy efficient windows that you can purchase.

What is insulating glass?
Insulating glass consists of two pieces of glass sealed to a spacer. This creates an insulated air space between the two pieces of glass, resulting in better thermal performance. Insulated glass also reduces condensation while keeping the heat in during the winter, and heat out during the summer.

What is Low-E Glass?
Low-E (Emissivity) glass is treated with thin, virtually invisible, transparent coatings of various layers including metal oxide and silver. During the winter, Low-E glass allows the sun's natural light and short-wave heat energy to freely pass through while reflecting long-wave heat energy back inside, keeping your home warmer. In the summer, Low-E glass reflects long-wave heat energy to the outside keeping your home cooler and, reduces the penetration of the sun's ultraviolet (UV) rays, minimizing the fading of carpet and draperies.

What is Low-E Glass with Argon Gas? How does it work?
Added inside an insulating glass unit with Low-E Glass, Argon gas is an invisible, insulating blanket that replaces most of the air during the manufacturing process. With Low-E reflecting heat away, Argon gas buffers thermal transfer to enhance the performance of the entire glass unit.

What is Krypton Gas?
Krypton Gas is an inert, odorless, colorless, tasteless, non-toxic gas that is denser than air. It is used to replace air between the glass panes in an insulating glass unit to reduce temperature transfer and deter convection (heat transfer by currents that flow from a warm surface to a colder surface).

What is an R-Value?
R-value measures the resistance a material has to heat flow. The higher the R-value, the greater the resistance, and the better the insulating quality.

What is a U-Value?
U-value measures the amount of heat transferred through a material. The lower the U-value, the slower the rate of heat flow and the better the insulating value.

What is Conduction?
Conduction refers to the energy transfer from one material to another by direct contact.

How should I evaluate the energy performance of a window or patio door?
Look for the National Fenestration Ratings Council (NFRC) label on the window or patio door. This label shows the U-Value, Solar Heat Gain, visible light transmittance and condensation resistance values.

ENERGY STAR® is a joint program of the U.S. Environmental Protection Agency and the U.S. Department of Energy helping us all save money and protect the environment through energy efficient products and practices. Energy efficient choices can save families about a third on their energy bill with similar savings of greenhouse gas emissions, without sacrificing features, style or comfort.

ENERGY STAR helps you make the energy efficient choice. If looking for new household products, look for ones that have earned the ENERGY STAR. They meet strict energy efficiency guidelines set by the EPA and US Department of Energy. If looking for a new home, look for one that has earned the ENERGY STAR. If looking to make larger improvements to your home, EPA offers tools and resources to help you plan and undertake projects to reduce your energy bills and improve home comfort. For more information, please visit the ENERGY STAR website at

When should I replace my windows?

  • When your windows have air leaks and drafts.
  • When your heating and cooling bills continue to rise.
  • When your windows are difficult to open and close.
  • When your windows do not provide adequate security for your home and family.
  • When your windows allow dust and dirt into your home.
  • When your windows don't block outside noise.
  • When your windows appear foggy.
  • When your windows are difficult to clean.
  • When your windows cost you time and money in maintenance.

What is the advantage choosing a custom replacement window over windows found in home centers?
The windows found in home centers and/or major lumberyards are typically stock sizes with little or no options. Replacement windows are custom made for each opening in your home, with the ability of choosing many energy saving and aesthetically appealing options.

What makes a vinyl window better than a wood window?
Vinyl windows are maintenance free, never needing staining or painting, they won't rot or split and are not susceptible to termites or other wood destroying insects.

Do replacement windows reduce condensation inside the home?
Although technology has improved with the inception of warm edge spacer systems, replacement windows will not eliminate condensation inside your home. In some cases replacement windows are so energy efficient condensation may be more evident after the old drafty windows are removed. Condensation and its intensity are directly related to the humidity level inside your home and the cold temperature outside.

How long will vinyl replacement windows last?
Thermal Industries Inc. was the first manufacturer in the United States to make a vinyl replacement window almost 50 years ago. We are one of the few manufacturers that have been in business longer than our warranty. Thermal Industries Inc. offers a lifetime warranty on all of its window products.

If my window gets broken, how do I fix it?
All of our branch distribution centers have factory trained service employees. Our service technicians can come to your home for service or you may bring any part to our distribution center and order a new replacement.

Do replacement windows meet building codes?
All of our products our manufactured to the AAMA standard and meet the NFRC requirements for Fenestration products. National and Local Building Codes may ask for additional requirements to meet codes in your area, such as egress and/or higher DP ratings. Check with your local Building Inspection office to see what the requirements are in your local municipality.

Are replacement windows easy to operate and clean?
Yes, all of our products are easy to clean and operate. Our double hung windows have a state of the art block and tackle balance system that is tailor made for your custom window, making it one of the easiest operating windows. They easily tilt in for safer cleaning from the inside of your home. Slider windows glide along a removable track on brass wheels for ease of operation and lift out for cleaning. And our casement window has an effortless operator that opens the window to a 110 degree position that allows for easy cleaning of the outside of the window from inside the home.

What is the difference between Bay Windows and Bow Windows?
Bay Windows consist of three windows in a single frame. The center lite is always twice as wide as the sidelites. Generally, Bay Windows are a combination of fixed centers, and two operable flankers (casements or double hung windows). Bay Windows project out from the house wall 30 or 45 degrees. Bow Windows consist of 3,4, or 5 windows in a single frame. All of the windows are equal size, and are generally a combination of fixed centers and two operable flankers (casement or double hung windows.) Bow Windows project from the wall of the house 15 degrees. Bow Windows are similar to Bay windows, but the Bow Window's combination of windows has a more circular arch appearance.

What are Air Chambers?
Small honeycomb spaces within the extruded sash and frame profiles that, help to insulate and strengthen the window.

What does PVC stand for?
Poly Vinyl Chloride, a plastic compound used in the manufacture of profiles for vinyl replacement windows.

What are window sashes?
A sash is the part of the window or door that contains the glass. What does "fusion-welded" mean? Fusion-welding is the process of joining materials by melting them together with extreme heat, resulting in the materials bonding into one piece. All Thermal Industries vinyl replacement windows feature fusion-welded frames and sashes.

What is a Balance System?
A balance system is a device for holding vertically sliding sashes in any position through the use of a spring or weight to counter balance the sash.

What is DreamGlas?
DreamGlas® is a type of glass that can have design patterns cut into the glass, color added to it, or different types of caming added to give the look of a traditional stained glass window.

What are Grids or Muntins?
Grids are decorative, horizontal or vertical bars installed between the glass panes to create the appearance of the sash being divided into smaller lites of glass.

What is Tempered Safety Glass?
Tempered Safety Glass is treated with high heat for strength. If tempered safety glass is broken, it will shatter into very small pieces instead of shards.


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