How to calculate the summer and winter power consumption?
- Thread starter jaehlee99
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Thank for your reply.
If Summer is not, how can I expect the power calculation with data sheet?
You used the ckt size
add up cond fan + evap fan + comp fla's
all results are in va not watts because the power factor is not considered
va should be used for ckt sizing anyways
I appreciate your help.
cond fan + evap fan + comp fla's = 0.5+0.77+5.6=6.87 A
MCA = 1.25 x (cond fan + evap fan + comp fla's) = 1.25 + 6.87 = 8.56 A
This is similar to MCA 9A in the data sheet. I might be wrong calculation. Would you please advise me ?
Correct
power consumption 6.87 x 208(?)
if in a home are you sure it's not 230?
208 is usually a 3 phase voltage
correct on the mca
iirc actually 1.25 x largest + sum of other motors
in this case doesn't make much of a difference
might be a small amount for controls too
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Saturn_Europa
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kwired
Electron manager
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- NE Nebraska
MCA is for determining minimum size of conductor needed. If it has across the line starting of compressor - the minimum setting of short circuit/ground fault protection will be higher then MCA.
Actual load will be less then MCA, actual load will depend on conditions present at time you measure load as well, if the unit is working harder, has plugged coils, filters it will have an impact on actual load. For calculations though you should assume it can draw as much as RLA of compressor plus FLA of other motors that will run simultaneously.
JFletcher
Senior Member
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- Williamsburg, VA
This is a Carrier vertical PTAC, yes? In heat pump mode, the power consumption is going to be the same winter or summer. If it has electric heat, it will use more power in winter than summer.
Cooling
On a call for cooling, the condenser fan and evaporator
blower are energized simultaneously. After 10 seconds the
compressor will energize.
Heating (heat pump units)
On a call for heating, the condenser fan and evaporator
blower are energized simultaneously and after 10 seconds
the compressor will energize.
Page 15 here:
http://www.americancoolingandheatin...rrier-product-data-specifications/52v-2pd.pdf
kwired
Electron manager
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- NE Nebraska
I agree, but will add that summer load is usually higher only because the unit is working harder. It is still same capacity unit so rating is still same heating or cooling, but on a really cold day there isn't as much heat in the outdoor air to absorb and actual load on the unit drops because it is moving less heat.
But for branch circuit/feeder/service calculations the full rating of the unit is what matters. And yes if there is backup resistance heat it is very likely higher load then the heat pump.
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