Questions on Replacing coils

A quick learner from Delaware says:
July 27, 2017
I need to replace the coil balances on 2 windows. The window weighs 15 to 16 pounds. I think I have identified the correct parts to order (8 lb Series 140 Quick-Tilt, Single) X 4 pcs. The attached photo only shows part of the current coil because the bottom part is no longer connected. Now for my questions...

1. If I were to use 2 of the 11 or 12 pound coils on each window would it open easier with less effort?

2. The current coils have an 8 on them so I assume that is the 8 pound coil but it is a duel coil and the 8 pound coil available here is a single coil. Does that matter? Do I have to replace it with a duel coil?

This will be the first attempt to complete this type of repair so any insight would be greatly appreciated.
Questions on Replacing coils
Profile picture of Paul
Paul from SWISCO responded:
August 1, 2017
I see what you mean about the single and double coil. If the sash weighs approximately 16 pounds, though, then the manufacturer suggests the S140-8. Each of these carries 8 pounds per side, so they should be perfect for your 16 pound sash. If you go any higher because the strength of the springs will make it difficult to lower the sashes.
A quick learner from Delaware says:
August 1, 2017
Thanks for the reply and recommendation. I will order the 8 pound as you suggested.
A quick learner from Delaware says:
August 6, 2017
Received my replacement parts the day after ordering. Once installed the windows are operating perfectly!
8 lb Series 140 Quick-Tilt, Single
8 lb Series 140 Quick-Tilt, Single
S140-08
$8.28
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