Window balance assembly including sash support bracket

A moving coil, constant force, curl spring window balance assembly for installation in a hung window assembly comprising a sash moveable between a raised position and a lowered position, the window balance assembly comprising:

• a mounting bracket configured to be fixedly attached to a jamb wall of the window assembly;
• a carrier slidably coupled to the mounting bracket, the carrier comprising a pair of projections;
• a curl spring having a first curled portion and a second uncurled portion, the first portion being coupled to the carrier and the second portion being coupled to the mounting bracket, the curl spring configured to provide a counter-balance force against a weight of the sash;
• and
• a sash support bracket comprising a pair of resilient leg portions, the sash support bracket positioned intermediate the carrier and the mounting bracket, the sash support bracket configured to be nested with the mounting bracket and configured to be fixedly attached to the jamb wall;
• wherein when the sash is in the raised position the pair of resilient leg portions of the sash support bracket is configured to operatively couple to the pair of projections of the carrier to provide a holding force to supplement the counter-balance force provided by the curl spring against the weight of the sash, and when the sash is moved from the raised position toward the lowered position the sash support bracket is configured to operatively uncouple from the carrier.