What type of window spring is this?

[Dr Harris]

Hello window wizards,
I've been tasked with freeing up a bunch of double hung windows that have been painted shut. I scraped the parting bead and tracks clear of paint and cut the sash free on all sides. Still, the window was nearly impossible to raise, and once raised I could hardly lower it. Finally, I decided to try adjusting what appeared to be the balance mechanism, accessed from the left and right sides of the middle rail. I crammed an allen key in and tried to turn it and realised it was spring loaded and very hard to twist. Something gave after twisting a bit, and then on lowering the sash this spiral tube with a spring inside came up and out as I lowered. I've never seen this kind of mechanism, and I have no idea if it can be salvaged or made to work properly. Can anyone tell me what this part is called, and if they recognise the maker of this item? I'm sure someone has installed these or taken them out before. If they can't be saved, what 504029is the solution to get such windows fully operational again?

[Simplicity]

It’s called a spiral sash spring.

https://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjU5LHsl5_0AhVMcCsKHa4iC3UQFnoECAYQAQ&url=https%3A%2F%2Fwww.bunnings.com.au%2Fproducts%2Fbuilding-hardware%2Fwindows%2Fwindow%2Fspiral-window-balances&usg=AOvVaw2HZa1ohqNlcUPy-BOn22NL

Cheers Matt

[Handyjack]

I'm not sure if this is your type or not but have a look at this web page.
UNIQUE Window Sash Balance Type B White 14mm Rebate-APT01/HA1 #35 | Keeler Hardware (https://www.keelerhardware.com.au/unique-window-sash-balance-type-b-white-14mm-rebate-apt01-ha1-35)
When I needed to change the springs on 4 windows, I was able to buy them in store. I have also seen them at Bunnings; but only a single size.

If it is this type of sash balance the good news is you do not need to remove the sashes to change them, but being able to prop the sash at its full height is extremely useful.

[Dr Harris]

Thanks to both of you. I figured out that it was a spiral spring balance, but I can't understand why it's emerged from the top of the mid rail. How are these adjusted? It seemed like there was an allen screw accessible from above the mid rail, left and right side. As I tried to turn that allen screw, the screw resisted and twisted back against my effort, like spring loaded. Then as I closed the window this spring coil came out the right side. So is it replaced by unscrewing a bracket from under the lower sash rail? I'd like to inform the client of how these can be repaired, but I'm not sure what the exact replacement part would be. looks like Bunnings has a slew of possible options, but how to know which it is?

[Handyjack]

The spring (tube) is attached to the frame at the top by a single screw. The bottom foot is attached to the sash by two screws. Prior to attaching the bottom the spring tension can be adjust by turning it.
What I found is that by having the sash lifted as high as possible and propped up I could then pull the foot down a little bit, turn it a few turns and then attach to the sash. You might need a few tries to get the tension right.
If you find a good hardware store which stock spring balances, take an old one in so you can get the right length. I bought mine at a Mitre 10 store.