Walf@ZWO LST will add one hour if daylight be set.
Why are you adding anything to the Local Sidereal Time? It is a fundamental number that is based on the Greenwich Mean Sidereal Time (GMST) and your Local Longitude.
If you add anything to the LST, it is no longer the LST.
The Greenwich Mean Sidereal Time is based on the exact time at the Greenwich Observatory in London when the Sun passes through the vernal equinox. GMST can be obtained from the Julian Date (which in turn can be obtained from UTC and Unix Date).
Daylight Saving changes the Local Time (when your alarm clock wakes you up in the morning). It does not determine the LST. Local Time and DST are based on UTC offset and Time Zone that your government wants you to be in, so that everybody goes to work at the same time.
For heaven's sakes get a copy of Jean Meeus, "Astronomical Algorithms," 2nd Edition, ISBN 0-943396-61-1 if you have forgotten what you had learned in Astronomy 101.
On a computer, you:
(1) get Julian Date either from UTC or Unix Time.
(2) compute the Greenwich Mean Sidereal Time (GMST) from the Julian Date (JD), (be sure to use at least 64 bit floating point numbers)
(3) Using the Local Longitude, compute the Local Sidereal Time (LST) from GMST.
That's it. There is no step 4. No UTC offset, no DST - those things are artifacts of society, not astronomical.
Every astronomical event is then based on LST. For example, the Hour Angle of your mount (where the motor of your mount points to) is simply
Hour Angle = LST - Right Ascension of target in the sky.
You know exactly where the Meridian (HA = 0) is, since that is when LST is equals RA.
See? No UTC offset, no Local time, no DST. And you Meridian Flip at the correct moment.