Most condensers operate at a single speed and capacity and either run for longer or shorter periods of time during hotter or cooler weather, respectively. Short run times (aka, short cycling) reduce efficiency. Multi-speed condensers typically have a high and low speed. This can be accomplished by two separate compressors inside a single condenser, or by a single dual-stage compressor. During cooler weather (aka, part load times) the condenser will run in low speed for longer run periods. When needed, the condenser can run in high speed.
Variable-speed condensers are not limited to just high and low speeds. They can gradually ramp from lowest to highest speeds as needed.
There are several features that can indicate that a condenser is multi-speed. These include:
- Product tags, labels and marketing names that indicate two-stage, dual-stage, multi-stage, etc.
- Two compressors observed by looking down through the condenser fan.
- High and low capacities or nominal tonnages indicated on nameplate.
The definitive way to determine if the condenser is multi-speed or variable speed is to record the make and model number and find the manufacturer’s specifications.