Recommendations for Installing spiral balances

Question

Hi there -

I am hoping to convert these double-hung wooden window sashes from spring balances to spiral balances. The sashes are 43"x43" and weigh around 20lbs each. Currently they have spring balances and aluminum jamb tracks. I want to ideally keep the aluminum jambs and install the spiral tubes in the existing setup.

I am wondering if you could tell me whether a 40" spiral balance would be suitable for these sashes even though they are 43". I plan to have the bracket attach at the bottom of the sash. I'm guessing the "red tipped" balances are appropriate given the weight of the sash.

Tom · Accepted Answer

Whenever we deal with old wood windows like this, our spiral balance of choice is the Series 500. We also use the 17-012 bracket (sold separately). The balance has a 9/16" diameter tube and its various spring strength options are usually rated for heavier sashes, though I highly recommend getting an exact weight before you pick any of them. You don't want to guess that.

As for length, I can't really say for sure if a 40" balance will work. We don't really base length on total sash size; instead, what you want to do is measure the height of the visible glass and then add 3" for the bottom sash and 1" for the top sash. For example, if the height of the visible glass for both sashes is 20", then you want a 23" long balance for the bottom and 21" for the top. Does that make sense?

Let me know what you get with that formula and I'll see what sizes are available. I will also need that precise sash weight just to be safe.