Coverting cast iron balance weights to newer method.

A home owner from USA says:

I've pulled four sash out of two windows to repair the woodwork and replace the glass. The new glass is much heavier than the old and the old weights won't hold them anymore so I'm investigating my options. I'm considering hiding a pulley in the current weight box, replacing with spring/tape balances and using spiral balances like yours. I like the spiral balance best but I need some help figuring out just what parts I need - and I think I might be out of the standard weight range as well.

Here are my windows:

  • All 1" thick wooden double hung sash with iron counterbalance weights, sash cord and passive pulley.
  • North Window Lower sash: 39" high, 43.2lbs (plus paint and putty)
  • West Window Lower sash: 39" high, 41.5lbs (plus paint and putty)
  • Both Windows, Upper sash: 23" high, 18lbs (plus paint and putty)
  • Bottom sash balance, North (44lb window): 1@#S500-40 only a bit beefier, like up to 45lbs?
  • Bottom sash balance, West (42lb window): 1@#S500-40 only a bit beefier, like up to 45lbs?
  • Bottom sash brackets: 4 @ #17-083
  • Top sash brackets - What do you recommend? Four more 17-083 as for the bottom sash?

Separately, I wonder if you can help me find replacements for two window lock handles that were lost by the previous owners. They latch an awning window closed. The other hardware (like crank handles) look like it matches what you carry. Attached is a photograph of one of the handles that wasn't lost.

Thank you in advance for your help,

Thumbnail of the uploaded file named IMG_20180726_142226904.jpg
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Tom from SWISCO responded:

Thanks for contacting us! I'm not sure if our spiral balances can work for you. Converting from coil balances to spiral balances is always tricky, and there's no guarantee things will go right. However, the Series 500 is pretty versatile and can work in a wide variety of older wood windows. We usually recommend a bracket like our 17-012 or 17-007.

As for weights, Black Tip is the absolute strongest they make. For the two 40" long balances, you won't be able to get anything stronger. If the Black Tip won't support those sashes, then nothing will.

Concerning the other three windows, I can't say for sure what size you need. Can you tell me the height of the visible glass? That will tell us what length would be appropriate.

Now for that lock. It's hard to determine what you have, since most of the mechanism is still installed and obscured by the window. See our 38-205 to start out. This may be similar to what you have now.

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