As a general rule you will want to use 1 hinge per every 30 inches of door. That said, different brands provide different closing force, spec and performance.
Regarding door height:
1. Doors up to 60 inches need 2 hinges.
2. Doors over 60 inches, but not over 90 inches, need to use 3 hinges.
3. Doors over 90 inches but not over 120 inches, 4 hinges are recommended.
Door weight is also a factor. For example, Waterson hinges support doors weighted 150-330lbs with three hinges; 260-440 mainly use four hinges. We recommend that you follow our closer hinge manufacturer spec. If your door requires three hinges then use three self-closing hinges. If your door requires four hinges then use four self-closing hinges. For more information, please feel free to see our website.
We recommend using three hinges for optimal performance. Each hinge provides a unique function — spring tension, swing speed control, and latch speed control, which when combined provide effective and smoothe closing. In addition, three hinges will greatly extend the overall lifetime of the set. If you do choose to use only two Waterson hinges, you may run into an alignment issue due to the fact that our hinge barrels are larger than conventional hinges. Therefore a 3rd non-Waterson hinge will not match from an alignment perspective. Plus a regular door hinge combined with two Waterson hinges will simply look unattractive.
Please contact us directly concerning doors over the above specifications.