If you have two price quotes for a freezing room, and both say "10 horsepower compressor," will the two units give you the same cooling? To compare, ask the suppliers the same question: How many kilowatts of cooling will each unit provide under the operating conditions of my room? The answer depends on the model of the unit, the refrigerant, and the evaporation and condensation temperatures at which the selection was made.
Horsepower, cooling kilowatts, and electrical kilowatts
| as stated in the price quote | means |
|---|---|
| the motor power in horsepower (HP) | the rated capacity of the compressor motor, if that is what the number in the quote refers to. |
| cooling capacity in kilowatts (Cooling Capacity) | the rate of heat extraction from the room under specific operating conditions. |
| the electrical power in kilowatts (Power Input) | the rate of electricity consumption at the operating point. Check if the number is for the compressor alone or for the entire unit. |
If you converted 10 horsepower to about 7.46 kilowatts on the calculator, you have converted the unit of motor power. To know the cooling capacity, refer to the performance table of the model under your project's operating conditions.
Two rooms of the same size may require different units
Imagine two rooms with the same dimensions and storage temperature. The first receives a refrigerated shipment once a day. The second receives warmer and more frequent shipments, and its door remains open longer during loading. The second room has an additional load from the goods and the air that enters when the door is opened. That's why, calculating the unit's capacity starts from the way the room is used in addition to its dimensions and insulation. ASHRAE 10.8 Refrigeration Load Calculations
How do you compare two offers? A practical example
Assume that the load calculation concluded that the room needs 8 kilowatts of cooling. The first offer states 9 kilowatts under your project's operating conditions, and the second offer states 10 kilowatts without specifying the measurement conditions.
You can directly compare the first offer's number with the room's requirement. To evaluate the second offer, request a re-selection with the same refrigerant and the specified evaporation and condensation temperatures for the project. And check the evaporator selection with the condenser unit, as both must match at the required operating point. The example is illustrative, and the numbers are hypothetical.
What data do you need before approving the offer?
- Model of the condenser unit, compressor, and evaporator and type of refrigerant.
- Cooling capacity in kilowatts under the project's design conditions.
- Evaporation and condensation temperatures used in the selection, or the design ambient temperature if the unit schedule is based on it.
- Electrical capacity and required supply, clarifying whether the declared electrical capacity includes the fans.
Do you have a price quote that only mentions the horsepower? Send to the team Bassem for Refrigeration Industries the room data and the price quote so we can review the cooling capacity with you under your project's operating conditions.