G3.3.2.4 Fan System Operation states: "If the supply fan is modeled as cycling and fan energy is included in the energy-efficiency rating of the equipment, fan energy shall not be modeled explicitly."
I have a project with PSZ-HP packaged heat pump units SEER 13.0 in the baseline design. Does the statement above mean that I can't use the equations in TABLE G3.1.2.9 Baseline Fan Brake Horsepower when setting up HVAC system fans in the DD wizard screen 4 of 7?
Any insights on this would be greatly appreciated.
Mark Beaudry
I could use an explanation of what ASHRAE App. G means by the word
"explicitly" in the context below?
cycling and fan
energy shall not be
baseline design. Does the statement above mean that I can't use the
equations in TABLE G3.1.2.9 Baseline Fan > Brake Horsepower when setting up
Mark,
In this context, "explicitly" means entering a non-zero value for fan
SUPPLY-STATIC or SUPPLY-KW/FLOW when using eQUEST. Most likely you will
be modeling the fan as continuous anyway (per G3.1.2.4) but even if you
model it as cycling you will need a non-zero fan power if you let eQUEST
calculate the EIR. eQUEST converts SEER and EER to EIR which has no fan
power, then adds fan power in the form of SUPPLY-STATIC. (Someone please
correct me if I'm wrong.)
Use the G3.1.2.9 equations for your baseline fan power. See attached for
reference. There is a lot of discussion in the archives (try "SEER EER
EIR") but none that I'd call definitive. I'm still trying to figure it
out.
Regards,
William Bishop, EIT, LEED(r) AP
Mark,
In order for eQUEST to calculate the EIR, you must enter the EER in the
wizard, then eQUEST will calculate the EIR in the detailed interface.
eQUEST will not calculate the EIR if you input the efficiency in the
detailed interface.
After eQUEST calculates the new EIR, you must use the formula to
calculate the fan energy and enter the information into the detailed
interface.
Otto
Has anyone been able to resolve warnings that occur with circulation
loops? Please see attached for simulation warnings.
Thanks,
Katie
Katie,
If you don't enter loop PIPE-HEAD the default will be 21.6' (per the
help menu), then coil and equipment head is added. Adjust these to match
the specified pump performance. Hopefully that will take care of some of
those warnings.
Regards,
Bill
The CURINV warnings you see are mostly related to pumps. What equest does
with its pump and loop calculations is a mystery and a bit of a joke (I
frequently see autosized flow rates 5 to 10 times the design). Chances are,
if you specify kW, flow and head together, you'll end up seeing the errors
you are getting here. Start with just the pump kW. Add head if eQuest
complains. You'll have to enter the head that the program calculates or,
again, you'll get more warnings.
Shaun Martin LEED AP