Unmet Load Hours?

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eQuest frustration question:

I have a VAV system with HW reheat and DX cooling. The AHU airflow is
auto-sized, the main HW heating coil is auto-sized, the zone VAV airflow
is auto-sized, the zone VAV HW reheat is auto-sized, and the zone HW
baseboard is auto-sized...why with all these auto-sized values will I
still have a warning that my zone has insufficient heating?? Wouldn't
eQuest auto-size the heating capacity to meet the load required? I have
numerous systems with unmet load hours because of this type of warning
and need some advice on how or where to start in my attempt to get rid
of these unmet load hours for my EAc1 submittal. Thanks.


ZONE EL4 West Perim Zn (G.W14)

might have insufficient heating capability.

Check that the SYSTEM or ZONE HEATING-CAPACITY plus this

ZONEs BASEBOARD-RATING is adequate to maintain the ZONE

specified DESIGN-HEAT-T for the calculated peak ZONE load

(see LS-A or LS-B for the ZONE peak load.)

Josh Greenfield, PE, REP, LEED AP

josh.greenfield's picture
Joined: 2011-02-17
Reputation: 0

It's time to do that thing again where we talk about unmet hours. I'll give a little 

background first: I'm new to equest and to the HVAC industry, so bear with me. The project is a big manufactures about (861112.8 foot2), split into 12 zones and predominantly served by series VAV terminals using chilled water. It's in Guanajuato,MX so and are no economizers. I've spent the majority of the past few days reading previous discussions and trying a variety of changes. I have attached the INP and PD2 for convenience.

I initially tried to represent the system based on the mechanical/electrical schedules, but that yielded many unmet hours (99%), so it is currently set to auto-size, but am still at about 600 unmet hours (7%). 7 of the zones are series VAV, 2 are single-zone with reheat, and one is a packaged single zone for the MDF room.

* Changing to an auto-sized system provided a large reduction in UH.

* I changed from 4°R to 8°R throttling range. It´s normal but How do I Know, until what number is good or bad? 

* am trying to not manipulate the data by adjusting the cooling/heating ratio.

* The setpoints are 74c/70h. I tried changing them a few degrees in either direction, but did not get a large enough reduction.

* have the fans cycling at night (no OA), which did help reduce the hours

* switched into DDE and set actual CFM from the mechanical plans. This resulted in an increase

. I think my inexperience hampers my ability to troubleshoot some of the problems because I don't necessarily have a good sense for what a reasonable result/prediction is.

I appreciate any assistance on this matter and am open to suggestions as far as proper modeling techniques and troubleshooting methods.


nacho's picture
Joined: 2013-04-24
Reputation: 0