[Equest-users] Boiler HEAT-EQUIP-CTRL for accurate part-load performance

[Bishop, Bill]

I have been experimenting with Equipment Control on a hot water loop to try to maximize the benefit of multiple condensing boilers, but I can't seem to reduce gas consumption below that using no equipment control (and for most of my experiments it actually increases). Condensing boilers are most efficient at part load. Obviously the first things to do to accurately capture the energy savings potential of condensing boilers (after setting BOILER:TYPE to "Condensing..." is to enter the following values:
BOILER:CAPACITY
BOILER:HEAT-INPUT-RATIO
BOILER:MIN-RATIO (a 20:1 turndown would be .05)
HW loop DESIGN-HEAT-T
HW loop LOOP-DESIGN-DT
HW loop HEAT-SETPT-CTRL to "OA Reset" with assigned HEAT-RESET-SCH
HW loop LOOP-OPERATION to "Demand" (if appropriate)

Is there a way to use Equipment Control to keep multiple boilers at part load while minimizing cycling losses from BOILER:START-UP-TIME and STANDBY-TIME, or does eQUEST stage the boilers efficiently automatically?
I have observed multiple old, large HW and steam boilers on a single loop running simultaneously when one boiler could clearly satisfy the load. Can anyone suggest a HEAT-EQUIP-CTRL to represent this? Does anyone have different START-UP-TIMEs or STANDBY-TIMEs suggestions based on field observations? Anyone know of any white papers or IBPSA presentations on the topic?

Thanks,
Bill

[Senior Energy Engineer 28Jun2012]<mailto:wbishop at pathfinder-ea.com>

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