Hello engTBR,
As I understand your specifications within the context of the Omron Digital Time Switch, you have described three “seasons” with 60, 21, and an undefined day length. I’ll assume there is similar repetition for each year.
Based on the H5S options. I would recommend the “4” models such as this 24 VDC option:
Be sure to verify appropriate voltage and mounting for your application. You can select from models: H5S-YB4-X, H5S-YB4D-X, H5S-YFB4-X, and H5S-YFB4D-X.
The 4-circuit module allow bank switching for each season with user defined start and stop dates. The 4-circuit module also allows the greatest flexibility for future expansion.
Should you desire additional flexibility, you may want to consider a full PLC. The disadvantage is the need to learn to program the device via a PC.
Please let us know if we can assist in the future,
Best Wishes,
APDahlen
P.S. From the datasheet:
Up to four seasons can be set for 4-circuit models, and up to two seasons for 2-circuit models.