Hi, Glenn. This code doesn't tell us what to recommend for you. It's possible that 29-14 means you have a 30" metal channel and a 14 pound sash. You'd need to measure the metal by itself, and remove and weigh the window sash, to confirm. Then, you can use the channel balance guide to compare your end pieces and choose a Series to match. Once you have the Series and length pinned down, the webpage for the product contains a chart that tells you which "option" to choose, based on your sash weight.
You don't want to use a spring strength that's higher than the weight of the sash, no. The way balances work is to provide constant upward force to counter-balance the constant downward force on the window panel, provided by gravity. If the upward force is higher than the downward force, then the window will be much more difficult to close. It could even drift open on its own.
You need a balance that is calibrated to your exact sash weight. Now, the exact weight isn't going to be stamped on the metal channel. Instead it will be a code that represents a specific calibration that we're often able to translate into more literal terms.
If your balance lacks any stamp at all, then you need to get the precise weight of your sash and tell us that, instead.
