TT entities reset config during summer-time change

[ragg987]

Describe the bug

Last night clocks in UK went forward. I noticed all my TT entities became unavailable at 02:18 BST / 01:18 UTC and then cycled back to available immediately.

This caused the entity setting to change back to the default configuration setting (I am assuming the 2 events are related, I have no way to prove it).

I use the action: target_timeframes.update_target_timeframe_config in home assistant e.g. to calculate and adjust heating and DHW slots dynamically. My config will have notional parameters in them which I adjust through the action.

Simple example:

• i set the TT config hours to 0 (meaning do not allocate a slot) for my HP heating)
• I use the action: to update the hours to 10 in the evening as that is what my heating energy needs call for
• TT will allocate the 10hrs and update the entity
• this works fine every other day of the year, but this year my heating stopped as the binary_sensor was reset to the default 0 hrs once config got reset and so my off automation kicked in
• note i also have a HA action that recovers the entity value after a restart

Reproduction steps

I have not tried to reproduce this.

Expected behaviour

Entity setting is preserved during the clock change.

Integration Version

1.5.0

Home Assistant Version

2026.3.4

Fresh Install?

Not specified

Home Assistant Logs

Example sensor history

29 March 2026
turned off
02:18:43 - 9 hours ago

became unavailable
02:18:43 - 9 hours ago

28 March 2026
turned on triggered by automation hvac_schedule_config_offset_libbi triggered by time change or manual update via template
20:00:00 - 14 hours ago

home-assistant_2026-03-29T10-12-40.297Z.log

Confirmation

• I confirm that I cannot find my solution within the documentation
• I confirm that I cannot find my solution within the FAQ

[github-actions]

This issue has become stale because it has been open for 30 days with no activity. If you still think it's an issue, please respond soon.

[ragg987]

I believe this issue should remain open, though it is low priority as it materialises when clock changes