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I am having a problem with heating unmet hours on a VAV system that appears to be an issue with the reheat coil. The problem only occurs in internal zones where the heating load on the coil is due to reheat only. On exterior spaces where there is envelope load there is not problem. The issue is most obvious in large spaces where ACH are high compared to internal loads. The VAV box is supplying air near 55F and not reheating to meet the temperature setpoint. It appear that the coil is not being sized for the reheat load and only for whatever exterior load exists which is none.

Here is my sizing:zone object C:\fakepath\Capture.PNG

Here is my sizing:system object C:\fakepath\Capture1.PNG

The loop set up is simple with a HW loop operating at 130F with a 40F delta T serving the air loop.

Does anyone have insight into why the coil is being sized incorrectly and I am seeing unmet hours?

I am having a problem with heating unmet hours on a VAV system that appears to be an issue with the reheat coil. The problem only occurs in internal zones where the heating load on the coil is due to reheat only. On exterior spaces where there is envelope load there is not problem. The issue is most obvious in large spaces where ACH are high compared to internal loads. The VAV box is supplying air near 55F and not reheating to meet the temperature setpoint. It appear that the coil is not being sized for the reheat load and only for whatever exterior load exists which is none.

Here is my sizing:zone object C:\fakepath\Capture.PNG

Here is my sizing:system object C:\fakepath\Capture1.PNG

The loop set up is simple with a HW loop operating at 130F with a 40F delta T serving the air loop.

Does anyone have insight into why the coil is being sized incorrectly and I am seeing unmet hours?

I am having a problem with heating unmet hours on a VAV system that appears to be an issue with the reheat coil. The problem only occurs in internal zones where the heating load on the coil is due to reheat only. On exterior spaces where there is envelope load there is not problem. The issue is most obvious in large spaces where ACH are high compared to internal loads. The VAV box is supplying air near 55F and not reheating to meet the temperature setpoint. It appear that the coil is not being sized for the reheat load and only for whatever exterior load exists which is none.

Here is my sizing:zone object C:\fakepath\Capture.PNG

Here is my sizing:system object C:\fakepath\Capture1.PNG

The loop set up is simple with a HW loop operating at 130F with a 40F delta T serving the air loop.

Does anyone have insight into why the coil is being sized incorrectly and I am seeing unmet hours?

I am having a problem with heating unmet hours on a VAV system that appears to be an issue with the reheat coil. The problem only occurs in internal zones where the heating load on the coil is due to reheat only. On exterior spaces where there is envelope load there is not problem. The issue is most obvious in large spaces where ACH are high compared to internal loads. The VAV box is supplying air near 55F and not reheating to meet the temperature setpoint. It appear that the coil is not being sized for the reheat load and only for whatever exterior load exists which is none.

Here is my sizing:zone object C:\fakepath\Capture.PNG

Here is my sizing:system object C:\fakepath\Capture1.PNG

The loop set up is simple with a HW loop operating at 130F with a 40F delta T serving the air loop.

Does anyone have insight into why the coil is being sized incorrectly and I am seeing unmet hours?