If Door Manufacture Plate/Information not available to provide Garage Door Total Weight, Then: 1) With Garage Door Fully-Open and supported, remove all existing Old Springs from Garage Door. (No Spring Assist) 2) Allow lowered Garage Door center to gently rest atop functioning bathroom scales (Record Door's Total Weight) 3) Match Door Total Weight to Rated Spring Load. (100Lbs to 200Lbs range) Spring Rate Explanation Link: https://www.abettergaragedoorinc.com/garage-doors/resources/114-understanding-the-garage-door-spring-color-code 4) Install two NEW springs with Garage Door in "Fully Opened" position. (Cables tight, but no Stretch in Springs) 5) Lower and Raise Door to test Spring assist. If more assist is needed, Fully-Open and stretch Spring a few inches at a time between tests. If less assist is needed, fully-Open and relax Cable tension. 6) Assist Goal should be, Lady can open and raise Garage Door with one hand/arm. This also provides proper assist for Garage-Door Openers. 7) Install Safety Cables Through NEW Springs. This will contain a Spring if it Fails while Streched. These stretched Springs contain incredible amounts of potential energy. I had one Spring fail, uncontained, and it bounced off the front and back walls of my Garage!! My Wife thought the sound from the failing Spring was our Water-Heater Exploding. Upon replacing that Spring, I immediately added Safety Cables to ALL our Garage Door Springs!!
Theoretically a Garage Door should be weight-balanced with the Springs so it can be opened or closed by a lady carrying a bag of Groceries or a Child (One-Piece or Multiple Panel Doors). That is why Automatic Garage-Door Openers do not need Large Motors. The Color-Code is simply the Weight-Classification of the Door. Determine the un-sprung weight of your door (Bathroom Scale). Select Two Springs based on the Door’s weight. Install the Springs with the Door in Up position (see instructions). While the Door is Open, adjust the Springs’ Preload equally on each side so the Door is easy to Open and Close with one hand. CAUTION: Make sure to Install the Safety-Cables through the centers of the Springs. There is an INCREDIBLE amount of Energy stored in the Springs when the Door is Down!!!
The cables that come with the springs are ample length. They must be threaded through the spring and anchored at both ends. With a seven foot door, your header track run is around 90 inches, and the max spring length is 68 inches, so cable length is no problem. The weight capacity of these specific springs is 140 lbs and your door is heavier, so you need a different set of springs for the increased weight. For safety, I strongly recommend that you stop by the Pro desk and have a professional advise you and maybe handle the job for you. You can get seriously hurt messing around with heavy garage doors, cables under tension, and strong springs. That, and if you don't do the job exactly right you can have many ongoing problems and additional expenses.
Probably no guarantee they are the same. You need to weigh the door, then review required spring needed at an on-line spring manufacturers site before you order. Before attempting your replacement, inspect your lifting cables to see if they are frayed anywhere and especially at the point attached to the frame. Mine were and because my door was very old I had to buy new cable (same diameter/safe weight limit) and make my own lifting cable. This was primarily because my door tracks did not provide the required anchor points and standard lifting cable lengths that you can buy at a hardware store were too short.
While there are no standards that can match other products in the market to our items, it is important to seek the services of a professional garage service company if you are unsure which spring to use. Using the incorrect spring based on the weight of the garage door can significantly impact the functionality of the door opener. The spring chosen by a consumer should be balanced to the weight of the garage door.
HD indicates it is 25 inches in the specs and is backed up by one answerer. My research indicates rest length is important. you should measure just the spring (not the loops) and replace with one that is alike.
You need to weigh the door, then review required spring needed at an on-line spring manufacturers site before you order. Alternatively, if your old spring has a color code and the door opener worked fine, order a spring with the same color markings. I reviewed install videos on Youtube, they are numerous. Before attempting your replacement, inspect your lifting cables to see if they are frayed anywhere and especially at the point attached to the frame. Mine were and because my door was very old I had to buy new cable (same diameter/safe weight limit) and make my own lifting cable. This was primarily because my door tracks did not provide the required anchor points and standard lifting cable lengths that you can buy at a hardware store were too short.
If it's a standard single-car 7 ft high WOOD sectional door, it's probably the 140 lb springs. If it's a single-car 7 ft high STEEL (the thin stuff) sectional door, it's probably 90 lb springs. The only absolute way to get the proper springs is to weigh the door. My advice: Weigh the door, look up the door specs online, or get a professional.