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Endura Flap Thermo Sash 3e Pet Doors for Sash Windows

Endura Flap Thermo Sash 3e Pet Doors for Sash Windows

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$509.99
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White
Bronze (Black)
Brushed Aluminum

  • Sash window insert with built-in pet door
  • Withstands extreme climates
  • Low-E glass installed to reduce harmful UV and infrared light
  • Easy to install and doesn't require semi-permanent installation
  • Locking cover included that loads from the top
  • Video to explain how to measure sash window track width

Product Details


The Endura Flap Thermo Sash 3e Pet Door for Windows is an insulating, weatherproof panel that fits snugly into the track of most windows. This semi-permanent door installs easily with a spring-loaded design that safely secures the panel in place without the hassle of permanent installation. The Thermo Sash 3e provides quality insulation and energy efficiency, as the perimeter of the flap contains magnets to keep the flap shut when not in use. This dog/cat door for window sashes will help keep your house at your desired temperature, and it gives your pets the freedom they crave without compromising your time! 

Features:

  • Frame color comes in white, dark bronze, and brushed aluminum
  • Pet flaps available in small to extra large
  • Sizes to fit windows from 22" - 43" in width and at least a 1" thick track. Customized sizes available
  • The frame is made from heavy extruded aluminum
  • Blocks UV rays and infrared light with Low-E glass
  • Polyolefin polymer flap is designed to remain flexible in temperatures below freezing down to -40 degrees
  • Remains sealed in heavy winds
  • Magnets line the sides of the flap to combat wind gusts and weather
  • One sturdy locking cover included that loads from the top
  • Draft stopper and weather stripping included for enhanced insulation
  • 90-day return policy and a lifetime warranty.

Benefits:

  • Sleek frame and color variety are complementary to many windows
  • The flexible flap is easy for pets to use
  • Polyolefin polymer flap is pet and environmentally friendly
  • Accommodates both dogs and cats
  • Multiple pets can use the door due to its taller and slimmer design
  • Temporary/semi-permanent installation is perfect for renters and vacation homes
  • Keep your pets inside or out with the locking cover
  • Gives pets the ability to come and go when they please

Size Chart

Flap SizeFlap DimensionHeight To Raise Window
Small6" w x 11" h18 1/2"
Medium8" w x 15" h22 1/2"
Large10" w x 19" h26 1/2"
Extra Large12" w x 23" h30 1/2"

 

For your adjustment range, you need to measure the length of your sash window track from the furthest left to right. The adjustment range of your pet door should ideally have your track length in the middle. The following adjustment ranges are available:

  • 22"-25"
  • 25"-28"
  • 28"-31"
  • 31"-34"
  • 34"-37"
  • 37"-40"
  • 40"-43"

Custom orders are subject to special restrictions.

Additional Information

Frame Material

Aluminum

Track Width Minimum

1"

Flap Thickness

7/8"

Warranty Period

Lifetime

Locking Cover Material

Molded ABS Plastic

Climate Suitability

Severe 4-Season

Ability to Lock Flap

Yes

Can Be Installed In

Sash Windows

Sealing Value

Very High

Installation Instructions

Installation icon Difficulty Easy
Installation icon Steps 04
Installation icon Time Required 0.5 hours
Installation icon Sections 01
Installation icon Flags 01

Parts

  • Sash Window Pet Door
  • Center Post Weather Seal Draft Stopper
  • Foam Weather Strip

Tools

  • None

Please read instructions & notes thoroughly before installation.

Step 1 Release Spring Mechanism

  • Loosen the width adjustment locks at the end of the pet door insert. This allows the spring mechanism to move freely from side to side.

Step 2 Check Panel Fit

  • Insert the sash into the window track. Push against the spring mechanism and swing the opposite end into the opposite window track. Gently release. Tighten the width adjustment locks.

Step 3 Apply Weatherstripping

  • Remove panel from window track.
  • Apply the foam weather-stripping by peeling back the paper and exposing the adhesive. Unroll it along the edge of the sash, pressing to ensure it adheres. Install on both the top and the bottom. Trim to fit with scissors.

Step 4 Mount Seal Draft Stopper

  • Mount the Center Post Weather Seal Draft Stopper. This strip prevents air from leaking between the window frame when raised to accommodate the sash. Trim to fit with scissors.
  • Put the panel back into the window track. Tighten width adjustment locks.

Switch the Side of the Flap

You can switch which side of the sash panel the pet door flap is on to best fit your home.

Step 1

  • Remove the screws on the top and bottom closest to the edge of the pet door. Then slightly loosen the screws closest to the glass. Next, slide off the side piece, then the flap assembly.

Step 2

  • Rotate the flap assembly (essentially flipping it upside down) then slide it back in. Make sure the locking cover is on the same side as the width adjustment locks.

Step 3

  • Replace the end spacer and screws.

LOCKING YOUR WINDOW

For a permanent lock, install a wood screw in the track immediately above the window on both sides. You will no longer be able to raise the window. For a temporary lock, place a removable wooden dowel or Charley bar in either track above the window, shown in Detail 1.

HEIGHT OF YOUR WINDOW

Make sure you place steps or ramps leading to your pet’s door at a height that works! When they go through the flap, the top of the flap should be at least 1" (2,5 cm) higher than the top of their back. Watch your pet and adjust as needed to keep them comfortable.

Videos

FAQ

What things should I measure/consider when choosing a cat flap door for my sash window?

Four things: 

  • 1. What size pet door your dog or cat will need
  • 2. How high you can raise the window (will it raise high enough to fit the pet door size you selected)
  • 3. The width of the window (from the deepest part of the left track to the deepest part of the right track)
  • 4. The width of the track (must be at least 1" to accommodate the Thermo Panel)
 

How do I determine the size of pet door my pet will need?

The door should be wide enough that it does not touch your pet's sides as they go through, and the top of the pet door should clear your pet's back by at least one inch. Take a look at our guide on how to measure your pet for more information. For a large cat door or dog door, make sure that the window you are installing in will accommodate the flap height you choose.

What makes the Thermo Sash 3e better than the other manufacturer's sash window pet doors?

The Thermo Sash includes the patented Endura Flap Pet Door which has a dual-layered flap employing magnets around the edges for superior sealability and insulation. It uses LoE glass for added insulating properties. Both of these are housed in a sturdy aluminum frame. It is made in the USA and backed by a lifetime warranty.

How wide does the window track have to be to accommodate the Thermo Sash 3e?

Your window track must be at least 1 inch wide for thermo sash 3e pet door installation.

Which Thermo Sashes are considered custom and are not returnable?

All Extra Large pet door sashes and any pet door size in a sash width with a 22"-25" adjustment range.

Can I move the flap on the Thermo Sash from the left side to the right?

Yes you can switch the side the pet door is on. You start by removing the screws on the top and bottom, then sliding the flap assembly out. Once it is removed you simply flip it upside down and slide it right back in. Next you put the screws back in, tighten them all down and you're finished. You'll want to make sure the thumb screws and locking cover are on the same side.

Can you make a Thermo Sash smaller than the 22" wide?

You can make it 3/4" inch smaller by trimming the right side (spring loaded piece). If this is not enough, we may be able to make a custom width with less or no glass. Please call us with your specific needs for us to review the possibility.

What tools are needed to install a Thermo Sash?

None. The Thermo Sash is installed without the use of tools. If desired, you may need tools to install a locking device to secure your window. Take a look at the Installations Instructions and Videos tab above.

How high do I have to raise my window to install the Thermo Sash?

It varies based on the pet door size: Small is 19", Medium is 23", Large is 27" and Extra Large is 31" high.

I ordered a 22"-25" adjustment range and mis-measured. My window is 25.5" wide. Is there anything I can do?

We make a width adjustment which extends the width by 3/4". You can order Patio panel height extensions for additional height. You could also cut, paint and use a small piece of wood to extend the width.

Can I adjust the height of the Thermo Sash?

The Thermo Sash does not have an adjustable height. The height of the unit is determined by the height of the pet door.

Which window cat door insert will keep out the desert heat?

The most energy efficient one is the Thermo Sash 3e Pet Doors for Sash Windows.

What energy saving dog door window insert do you have?

The Thermo Sash 3e pet door is the most energy efficient pet door window insert on the market.

I see the Thermo Sash 3e Pet Door for Sash Windows, what side sliding window cat door do you offer?

There is a vertical version of the Thermo Sash called the Thermo Panel. I is available in the same four flap sizes. It has three standard height ranges. If your window is shorter, a custom panel can be made.

Do you make Doggie Doors for Windows?

Yes! The Thermo Sash is designed for windows that lift up and down. The Thermo Panel is designed for windows that slide left to right. Both are available in Custom sizes.

Can I install a dog door in window if the window is not at ground level.

Yes. We've seen many creative ways to help our dog access the window. Pet parents usually install steps or a ramp on both sides of the window to the doggy access the window. This may require training, but can be successful.

How much does shipping cost?

Shipping is calculated at checkout.

Warranty

Endura Flap products have a lifetime warranty against defects in materials and workmanship under standard regular use. Damage caused by not using the product as intended, improper installation, and chewing is not covered under this warranty.



Customer Reviews

Customer Reviews
4.8 Based on 41 Reviews
5 ★
85% 
35
4 ★
12% 
5
3 ★
2% 
1
2 ★
0% 
0
1 ★
0% 
0
Customer Photos
Write a Review Ask a Question

Thank you for submitting a review!

Your input is very much appreciated. Share it with your friends so they can enjoy it too!

Filter Reviews:
JC
07/06/2022
Jim C.
United States

Endura Flap Thermo Sash 3e Pet Doors for Sash Windows

Fits and Works great

A PetDoors.com Customer
SM
05/30/2022
Sue M.
United States United States

Wonderful!

It was extremely easy to install, and our puppy knew just what to do…he could barely wait for me to finish installing. We wish we had thought of this years ago. The window is in our walk-out basement and allows hime to safely go outside to a kennel we put up outside the window.

PetDoors.com Endura Flap Thermo Sash 3e Pet Doors for Sash Windows ReviewPetDoors.com Endura Flap Thermo Sash 3e Pet Doors for Sash Windows Review
A PetDoors.com Customer
LE
02/08/2022
Lura E.
United States United States

Great product

I mismeasured the first time I ordered but got the correct size the second time, and appreciated the company’s help in returning the wrong one. We have the flap installed in our bedroom window but our stubborn Sheltie refuses to open it herself. She will go in and out as long as we hold it open, but that defeats the purpose. I wish we had gotten it sooner: she’s 4 years old now.

D
07/26/2017
Diane

Amazing Pet Door!

My dog loves her pet door, I love that it is high quality, nice looking, easily installed and fairly insulated from the Texas heat and as a Realtor, I love that it is not permanent and won't leave any evidence of ever being in the window.

J
03/15/2017
Joseph

Expensive but fantastic

I was skeptical, but I think it's definitely worth having a good product.

Endura Flap Thermo Sash 3e Pet Doors for Sash Windows

White / Small / 22" - 25" Edit

white endura thermo sash 3e for sash windows

Size Chart

Flap SizeFlap DimensionHeight To Raise Window
Small6" w x 11" h18 1/2"
Medium8" w x 15" h22 1/2"
Large10" w x 19" h26 1/2"
Extra Large12" w x 23" h30 1/2"

 

For your adjustment range, you need to measure the length of your sash window track from the furthest left to right. The adjustment range of your pet door should ideally have your track length in the middle. The following adjustment ranges are available:

  • 22"-25"
  • 25"-28"
  • 28"-31"
  • 31"-34"
  • 34"-37"
  • 37"-40"
  • 40"-43"

Custom orders are subject to special restrictions.

Frame Material

Aluminum

Track Width Minimum

1"

Flap Thickness

7/8"

Warranty Period

Lifetime

Locking Cover Material

Molded ABS Plastic

Climate Suitability

Severe 4-Season

Ability to Lock Flap

Yes

Can Be Installed In

Sash Windows

Sealing Value

Very High

Installation Instructions

Installation icon Difficulty Easy
Installation icon Steps 04
Installation icon Time Required 0.5 hours
Installation icon Sections 01
Installation icon Flags 01

Parts

  • Sash Window Pet Door
  • Center Post Weather Seal Draft Stopper
  • Foam Weather Strip

Tools

  • None

Please read instructions & notes thoroughly before installation.

Step 1 Release Spring Mechanism

  • Loosen the width adjustment locks at the end of the pet door insert. This allows the spring mechanism to move freely from side to side.

Step 2 Check Panel Fit

  • Insert the sash into the window track. Push against the spring mechanism and swing the opposite end into the opposite window track. Gently release. Tighten the width adjustment locks.

Step 3 Apply Weatherstripping

  • Remove panel from window track.
  • Apply the foam weather-stripping by peeling back the paper and exposing the adhesive. Unroll it along the edge of the sash, pressing to ensure it adheres. Install on both the top and the bottom. Trim to fit with scissors.

Step 4 Mount Seal Draft Stopper

  • Mount the Center Post Weather Seal Draft Stopper. This strip prevents air from leaking between the window frame when raised to accommodate the sash. Trim to fit with scissors.
  • Put the panel back into the window track. Tighten width adjustment locks.

Switch the Side of the Flap

You can switch which side of the sash panel the pet door flap is on to best fit your home.

Step 1

  • Remove the screws on the top and bottom closest to the edge of the pet door. Then slightly loosen the screws closest to the glass. Next, slide off the side piece, then the flap assembly.

Step 2

  • Rotate the flap assembly (essentially flipping it upside down) then slide it back in. Make sure the locking cover is on the same side as the width adjustment locks.

Step 3

  • Replace the end spacer and screws.

LOCKING YOUR WINDOW

For a permanent lock, install a wood screw in the track immediately above the window on both sides. You will no longer be able to raise the window. For a temporary lock, place a removable wooden dowel or Charley bar in either track above the window, shown in Detail 1.

HEIGHT OF YOUR WINDOW

Make sure you place steps or ramps leading to your pet’s door at a height that works! When they go through the flap, the top of the flap should be at least 1" (2,5 cm) higher than the top of their back. Watch your pet and adjust as needed to keep them comfortable.

Videos

FAQ

What things should I measure/consider when choosing a cat flap door for my sash window?

Four things: 

  • 1. What size pet door your dog or cat will need
  • 2. How high you can raise the window (will it raise high enough to fit the pet door size you selected)
  • 3. The width of the window (from the deepest part of the left track to the deepest part of the right track)
  • 4. The width of the track (must be at least 1" to accommodate the Thermo Panel)
 

How do I determine the size of pet door my pet will need?

The door should be wide enough that it does not touch your pet's sides as they go through, and the top of the pet door should clear your pet's back by at least one inch. Take a look at our guide on how to measure your pet for more information. For a large cat door or dog door, make sure that the window you are installing in will accommodate the flap height you choose.

What makes the Thermo Sash 3e better than the other manufacturer's sash window pet doors?

The Thermo Sash includes the patented Endura Flap Pet Door which has a dual-layered flap employing magnets around the edges for superior sealability and insulation. It uses LoE glass for added insulating properties. Both of these are housed in a sturdy aluminum frame. It is made in the USA and backed by a lifetime warranty.

How wide does the window track have to be to accommodate the Thermo Sash 3e?

Your window track must be at least 1 inch wide for thermo sash 3e pet door installation.

Which Thermo Sashes are considered custom and are not returnable?

All Extra Large pet door sashes and any pet door size in a sash width with a 22"-25" adjustment range.

Can I move the flap on the Thermo Sash from the left side to the right?

Yes you can switch the side the pet door is on. You start by removing the screws on the top and bottom, then sliding the flap assembly out. Once it is removed you simply flip it upside down and slide it right back in. Next you put the screws back in, tighten them all down and you're finished. You'll want to make sure the thumb screws and locking cover are on the same side.

Can you make a Thermo Sash smaller than the 22" wide?

You can make it 3/4" inch smaller by trimming the right side (spring loaded piece). If this is not enough, we may be able to make a custom width with less or no glass. Please call us with your specific needs for us to review the possibility.

What tools are needed to install a Thermo Sash?

None. The Thermo Sash is installed without the use of tools. If desired, you may need tools to install a locking device to secure your window. Take a look at the Installations Instructions and Videos tab above.

How high do I have to raise my window to install the Thermo Sash?

It varies based on the pet door size: Small is 19", Medium is 23", Large is 27" and Extra Large is 31" high.

I ordered a 22"-25" adjustment range and mis-measured. My window is 25.5" wide. Is there anything I can do?

We make a width adjustment which extends the width by 3/4". You can order Patio panel height extensions for additional height. You could also cut, paint and use a small piece of wood to extend the width.

Can I adjust the height of the Thermo Sash?

The Thermo Sash does not have an adjustable height. The height of the unit is determined by the height of the pet door.

Which window cat door insert will keep out the desert heat?

The most energy efficient one is the Thermo Sash 3e Pet Doors for Sash Windows.

What energy saving dog door window insert do you have?

The Thermo Sash 3e pet door is the most energy efficient pet door window insert on the market.

I see the Thermo Sash 3e Pet Door for Sash Windows, what side sliding window cat door do you offer?

There is a vertical version of the Thermo Sash called the Thermo Panel. I is available in the same four flap sizes. It has three standard height ranges. If your window is shorter, a custom panel can be made.

Do you make Doggie Doors for Windows?

Yes! The Thermo Sash is designed for windows that lift up and down. The Thermo Panel is designed for windows that slide left to right. Both are available in Custom sizes.

Can I install a dog door in window if the window is not at ground level.

Yes. We've seen many creative ways to help our dog access the window. Pet parents usually install steps or a ramp on both sides of the window to the doggy access the window. This may require training, but can be successful.

How much does shipping cost?

Shipping is calculated at checkout.

Warranty

Endura Flap products have a lifetime warranty against defects in materials and workmanship under standard regular use. Damage caused by not using the product as intended, improper installation, and chewing is not covered under this warranty.

Customer Reviews
4.8 Based on 41 Reviews
5 ★
85% 
35
4 ★
12% 
5
3 ★
2% 
1
2 ★
0% 
0
1 ★
0% 
0
Customer Photos
Write a Review Ask a Question

Thank you for submitting a review!

Your input is very much appreciated. Share it with your friends so they can enjoy it too!

Filter Reviews:
JC
07/06/2022
Jim C.
United States

Endura Flap Thermo Sash 3e Pet Doors for Sash Windows

Fits and Works great

A PetDoors.com Customer
SM
05/30/2022
Sue M.
United States United States

Wonderful!

It was extremely easy to install, and our puppy knew just what to do…he could barely wait for me to finish installing. We wish we had thought of this years ago. The window is in our walk-out basement and allows hime to safely go outside to a kennel we put up outside the window.

PetDoors.com Endura Flap Thermo Sash 3e Pet Doors for Sash Windows ReviewPetDoors.com Endura Flap Thermo Sash 3e Pet Doors for Sash Windows Review
A PetDoors.com Customer
LE
02/08/2022
Lura E.
United States United States

Great product

I mismeasured the first time I ordered but got the correct size the second time, and appreciated the company’s help in returning the wrong one. We have the flap installed in our bedroom window but our stubborn Sheltie refuses to open it herself. She will go in and out as long as we hold it open, but that defeats the purpose. I wish we had gotten it sooner: she’s 4 years old now.

D
07/26/2017
Diane

Amazing Pet Door!

My dog loves her pet door, I love that it is high quality, nice looking, easily installed and fairly insulated from the Texas heat and as a Realtor, I love that it is not permanent and won't leave any evidence of ever being in the window.

J
03/15/2017
Joseph

Expensive but fantastic

I was skeptical, but I think it's definitely worth having a good product.