Ron DomitrovicProgram Manager, Energy Efficiency

Variable Capacity HP Subcommittee8/28/2013

Load Based Testing for Unitary HVAC

2© 2013 Electric Power Research Institute, Inc. All rights reserved.

Load Based Testing of Variable Systems

• Psychrometric rating testing is standard for unitary HVAC equipment

– 80°/67° is accepted as THE standard

– Controlled return air conditions

– Measured capacity/power/efficiency with system on.

• Works well for single-speed HVAC systems

3© 2013 Electric Power Research Institute, Inc. All rights reserved.

Load Based Testing of Variable Systems

• Common standards:

– AHRI 210/240: Systems < 65,000Btu/hr

– AHRI 340/360: Systems > 65,000 Btu/hr

– ANSI/AHRI 1230: VRF systems <300,000 Btu/hr

4© 2013 Electric Power Research Institute, Inc. All rights reserved.

Load Based Testing of Variable Systems

– Designed for fair comparison among similar systems

– NOT primarily designed for energy calculation

• However; generally OK with single speed systems

• Difficulties with variable capacity systems

THESE ARE RATING STANDARDS

5© 2013 Electric Power Research Institute, Inc. All rights reserved.

Load Based Testing of Variable Systems

– Why?

• Current standards require fixed operation

• Fixed operation may not capture actual (field) behavior

• Systems can be configured for optimal operation (for rating)

– May or may not match field operation

• Energy use is dependant on actual operation

6© 2013 Electric Power Research Institute, Inc. All rights reserved.

Load Based Testing of Variable Systems

• Load Based Testing

– Also called “calorimetric testing”

– Load on system is held constant

– No fixed control of system under test

– ASHRAE TC 8.11 is exploring possibilities

– Potentially more appropriate for energy calculation

– More difficult—labs are not currently set up for it

7© 2013 Electric Power Research Institute, Inc. All rights reserved.

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