Thermo Sash 3e Pet Door for Sash Windows
40
- Durable and insulating pet door for windows
- Dual-pane, Low-E glass and sturdy aluminum framing
- Energy-efficient flap design keeps home insulated
- Various flap sizes, colors, and adjustment ranges to fit your pet and your window
- Strong and sturdy Locking Cover included to secure your home and pet
- Easy to install and doesn't require semi-permanent installation, perfect for renters and vacation homes
Extreme Weather Resistance
Install Multiple
Tool-Free Installation in Minutes
Product Details
- Highly insulating flap with a complete magnetic seal, designed to stay closed in winds up to 50mph
- Complete magnetic seal designed to stay closed in winds up to 50mph
- Polyolefin polymer flap keeps your home comfortable in temperatures between -40 and 110℉
- Dual-pane, LoE glass gives you extra insulation for your home, pairs perfectly with newer energy-efficient windows
- Four sizes available to fit cats to large breed dogs
- Fits all vertical sliding sash window widths with a track width of at least 1"
- Draft stopper and weatherstripping included for extra insulation and weather resistance
- Easy, tool-free installation in a matter of minutes
Need help Installing? Take a look at our Thermo Sash Installation page.
Find The Best Pet Door Size For My Pet
A
Pet Height: inches
B
Pet Width: inches
Size Chart
| Flap Size | Flap Dimension | Height To Raise Window |
|---|---|---|
| Small | 6" w x 11" h | 18 1/2" |
| Medium | 8" w x 15" h | 22 1/2" |
| Large | 10" w x 19" h | 26 1/2" |
| Extra Large | 12" w x 23" h | 30 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. Custom orders are subject to special restrictions. The following adjustment ranges are available:
- 22"– 25"
- 25"– 28"
- 28"– 31"
- 31"– 34"
- 34"– 37"
- 37"– 40"
- 40"– 43"
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.
![](https://cdn.shopify.com/s/files/1/0325/4524/3274/files/sash_7.png?v=1626304819")
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
Installing a Thermo Sash 3e
How to Measure Your Door for a Sash Window Pet Door
Variable Magnetic Resistance
Replacing the Flap in the Sash Pet Door
Switching Flap Sides
Additional Switch the Side of the Flap
Wind Test
FAQ
|
Does the Thermo Sash have an adjustable height? No, the unit’s height is determined by the height of the pet door. |
|
If my window is not ground level, can I still install a dog door? Yes. There are many creative ways to give your dog access to the window, including installing steps or a ramp on both sides of the window. |
|
Can I change which side (left or right) the flap is on? Yes, you can switch which side of the panel 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. |
|
Is the Thermo Sash available in sizes smaller than the 22" wide? You can make it 3/4" inch smaller by trimming the spring loaded piece on the right side of the panel. If this is not enough, we may be able to make a custom width with less or no glass. Please contact our customer service team with your specific needs for us to review the possibility. |
|
How high do I have to raise my window in order to install the Thermo Sash? It can vary based on the size of your pet door:
|
|
How wide must the window track be to accommodate the Thermo Sash 3e? For installation, your window track must be at least 1 inch wide. |
|
I ordered the wrong size. Is there a way to make my panel bigger? If your door is too short, you can order the patio panel height extension to add additional height. |
|
Which of the 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 are considered custom and are not returnable. |
|
What makes the Endura thermo sash so great? There has been lots of discussion as to why the Endura Flap is such a high performing pet door, but for engineers or those looking for some more technical information here is a 74-page‚ dog door energy efficiency study‚ showing what makes it so special. This insulated window cat door will keep your energy bill low. |
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
- Reviews
- Questions
Thermo Sash 3e Pet Door for Sash Windows
I bought this door for the catio I built outside a bedroom window and it is exactly what I was hoping for. Keeps the cold out and the cat happy. Being able to change which side the flap is on is a huge bonus. It's a well designed window/pet door and built to last. I'm very glad I bought it!
United Stateswell made and so easy to install
This product is a life saver for me as I don't have to wake up to my cat crying to go out anymore. I have 3, one conquered it in about 2 weeks (I did put masking tape over the magnets to lessen the strength and I did prop the door open with a jar so that the cats get used to coming and going through it. My second cat is just on the verge and if I push his paw through, he can take it from there. My third is fickle and scared of everything, not sure he'll ever conquer but when the weather is nice and I don't need heat or air, I still prop the door open. I did build a little staircase out of paver stones on both sides to help them get thru and I have a small cat castle on both sides of window portion so that they can look thru while they try to figure it out. Yes, they are beyond spoiled. The window is very well made and we have had some crazy winds and it didn't effect it one way or another.
United StatesWindow Dog Door - Great Solution
I live in a beautiful Dutch Colonial house with lots of old quirks that fit the house. I didn't want to damage a door or put a whole in a wall. I found this window insert and it is the perfect solution to my dilemma. It allows my dog to go in and out while protecting the integrity of my house. The window insert arrived packaged well. It was easy to install and works as described. I am very satisfied and would repurchase this item if I had a similar need.
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 permanant and won't leave any evidence of ever being in the window.
Expensive but fantastic
I was skeptical, but I think it's definitely worth having a good product.
Find The Best Pet Door Size For My Pet
A
Pet Height: inches
B
Pet Width: inches
| Flap Size | Flap Dimension | Height To Raise Window |
|---|---|---|
| Small | 6" w x 11" h | 18 1/2" |
| Medium | 8" w x 15" h | 22 1/2" |
| Large | 10" w x 19" h | 26 1/2" |
| Extra Large | 12" w x 23" h | 30 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. Custom orders are subject to special restrictions. The following adjustment ranges are available:
- 22"– 25"
- 25"– 28"
- 28"– 31"
- 31"– 34"
- 34"– 37"
- 37"– 40"
- 40"– 43"
Installation Instructions
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
Installing a Thermo Sash 3e
How to Measure Your Door for a Sash Window Pet Door
Variable Magnetic Resistance
Replacing the Flap in the Sash Pet Door
Switching Flap Sides
Additional Switch the Side of the Flap
Wind Test
FAQ
|
Does the Thermo Sash have an adjustable height? No, the unit’s height is determined by the height of the pet door. |
|
If my window is not ground level, can I still install a dog door? Yes. There are many creative ways to give your dog access to the window, including installing steps or a ramp on both sides of the window. |
|
Can I change which side (left or right) the flap is on? Yes, you can switch which side of the panel 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. |
|
Is the Thermo Sash available in sizes smaller than the 22" wide? You can make it 3/4" inch smaller by trimming the spring loaded piece on the right side of the panel. If this is not enough, we may be able to make a custom width with less or no glass. Please contact our customer service team with your specific needs for us to review the possibility. |
|
How high do I have to raise my window in order to install the Thermo Sash? It can vary based on the size of your pet door:
|
|
How wide must the window track be to accommodate the Thermo Sash 3e? For installation, your window track must be at least 1 inch wide. |
|
I ordered the wrong size. Is there a way to make my panel bigger? If your door is too short, you can order the patio panel height extension to add additional height. |
|
Which of the 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 are considered custom and are not returnable. |
|
What makes the Endura thermo sash so great? There has been lots of discussion as to why the Endura Flap is such a high performing pet door, but for engineers or those looking for some more technical information here is a 74-page‚ dog door energy efficiency study‚ showing what makes it so special. This insulated window cat door will keep your energy bill low. |
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
- Reviews
- Questions
Thermo Sash 3e Pet Door for Sash Windows
I bought this door for the catio I built outside a bedroom window and it is exactly what I was hoping for. Keeps the cold out and the cat happy. Being able to change which side the flap is on is a huge bonus. It's a well designed window/pet door and built to last. I'm very glad I bought it!
United Stateswell made and so easy to install
This product is a life saver for me as I don't have to wake up to my cat crying to go out anymore. I have 3, one conquered it in about 2 weeks (I did put masking tape over the magnets to lessen the strength and I did prop the door open with a jar so that the cats get used to coming and going through it. My second cat is just on the verge and if I push his paw through, he can take it from there. My third is fickle and scared of everything, not sure he'll ever conquer but when the weather is nice and I don't need heat or air, I still prop the door open. I did build a little staircase out of paver stones on both sides to help them get thru and I have a small cat castle on both sides of window portion so that they can look thru while they try to figure it out. Yes, they are beyond spoiled. The window is very well made and we have had some crazy winds and it didn't effect it one way or another.
United StatesWindow Dog Door - Great Solution
I live in a beautiful Dutch Colonial house with lots of old quirks that fit the house. I didn't want to damage a door or put a whole in a wall. I found this window insert and it is the perfect solution to my dilemma. It allows my dog to go in and out while protecting the integrity of my house. The window insert arrived packaged well. It was easy to install and works as described. I am very satisfied and would repurchase this item if I had a similar need.
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 permanant and won't leave any evidence of ever being in the window.
Expensive but fantastic
I was skeptical, but I think it's definitely worth having a good product.
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