estimating kWh use for a freezer

[scstevemclark]

are there any guidelines for estimating the energy kWh consumption for a walk in freezer?

I am an energy auditor working on apartment building that has a 64 sq ft walk in freezer with a Copeland Copelamatic KAMB-007-CAV-800 3/4 HP compressor that is running all the time....is the compressor HP sufficienct to estimate power?

Is it normal for the compressor to run all the time? the insulation and seals are good on the unit.

finally, what is needed to estimate power consumption for commercial fridges and freezers?

thank you!
Steve

[Brian_UK]

No the compressor should not run all of the time if it is sized correctly.

If you are an auditor why don't you measure the power being used, much more accurate than an estimate.

[tmm]

Please consider the following in your calcs:

• Good practice dicates that you size the plant for 16Hr operations.
• Whilst you have confirmed that the compressor is single-phase, designed for R404a, attempting any derivation from the HP fails to recognise the evap/condenser fans/motors etc.
• The easiest solution therefore is to amp probe the reading for the system [typically from the local distribution board]. Recording this it remains only to modify ohms law to produce power from the known variable of voltage and current. Knowing the anticipated operational duration you can calculate a figure for Kwh/Period
• The positive side of this approach being that you are recording actual conditions which must be default consider wear and tear over the previous year(s) of usage.

Given you state that the compressor never stops issues must be ratified before you commit to reporting your findings.

tmm

[Magoo]

Hire a power analyser, with data logging and apply to power supply to that system. Operate for a week or longer. To get a better average.