Troubleshooting Unmet Hours

Sometimes the reason for an unmet hour is not immediately obvious.

Follow the steps below until the reason(s) for the unmet hour becomes apparent.

  • If necessary, resimulate the system with all results turned on (we need to know which hours are unmet and see temperatures).

  • Pick a zone and hour from the list of unmet hours.

  • Find out whether the temp is getting too high or too low for this zone and hour.

  • Is there a zone component that should be dealing with this unmet hour (radiator, fancoil, etc.)? Why isn’t it dealing with it (bad schedule, no capacity)?

  • Is there something wrong with the supply air temperature into the zone (if there is airflow)? Why? Coils too small? Bad controls?

  • Is there something wrong with the supply air flow rate into the zone? Why? Sized too small? Not flowing at all? Bad fan schedule? Bad controls?

  • Is this zone behaving differently from the other zones it is grouped with? Why?

  • Does the unmet hour correspond to an hour with a failure to converge? Are there lots of failures to converge? Any idea why? Most common reasons for failure to converge are control bands which are too narrow, and conflicting controls; these both cause the system to iterate between unstable conditions and never reach a stable solution (this is the meaning of failure to converge).

  • Does it make sense for the zone to be trying to control its temperature to this limit at this time?

  • Are the temperatures very different from the TSD results for this same hour?

If the reason is still not obvious, pick a different zone/hour and try again.