Take your AC voltage, when full-wave rectifying it you'll have VACx1.414 as an off-load DC across your primary smoothing Capacitor. In your case that could be 27.6 x 1.414 = 39v. An inductor isn't going to do much for you... you need to loose 10-15 volts somewhere or use a different AC source. Your Transformer might be 24v... but it might also have additional tappings (ie 12-0-12) or similar.