A quick learner from Albuquerque NM says:
August 18, 2016
Hello, my windows have the 2740 28" S350 window balance installed. Several windows have become too stiff to close down! I weighed the sash and found it to be 19lbs, which qualifies for either the 2730 or 2740. So I ordered the 2730 and 2740 to try them out. The best seems to be in between. So the question: do you recommend using one 2740 and one 2730 on each window, or is it better to select only one spring tension for the window? Second, my window housings seem to be EXTREMELY wide, meaning that at the top I can scoot them side to side or actually miss catching one of the window balances as I am reinstalling. Is there a top guide that would fix this or what do you recommend? Last, do these springs tend to stiffen over time, or does the tension remain about the same?
Paul from SWISCO responded:
August 19, 2016
I'm not sure what you mean when you mention the window housing is too wide. Are you referring to the track that holds the balance? If so, you may want to consider our S385-28 channel balance. The attachments for this balance have wings that can stabilize it in the track. In regards to the spring weight, some window manufacturers have mixed the spring weight like you suggest, but in an ideal world you would have the same stamp on each side. I would go with the option that works best and use two of that. Finally, since you're in New Mexico, I wouldn't think you would have a rust problem. You can occasionally remove them and give them a lite spray of oil. The springs will gradually weaken as time and use goes by. The average lifespan of a balance is 5-10 years.