Heat Pump Technology Flashcards

What is the primary difference between a two-pipe and a four-pipe fan coil heat pump system in commercial applications?

Answer: Two-pipe systems provide either heating or cooling at one time; four-pipe systems can provide both simultaneously to different zones

Four-pipe systems have separate supply and return lines for both hot and chilled water, allowing simultaneous heating and cooling in different zones, while two-pipe systems switch seasonally.

What is 'cold weather staging' in a heat pump system with auxiliary electric heat?

Answer: A thermostat strategy that energizes auxiliary heat only after the heat pump cannot maintain setpoint

Cold weather staging energizes auxiliary heat strips only when the heat pump alone cannot maintain the indoor setpoint, maximizing efficiency by using the more efficient heat pump first.

A ground-source heat pump uses a horizontal closed-loop ground field. What soil condition would MOST negatively impact system efficiency?

Answer: Dry, sandy, or rocky soil with low thermal conductivity

Dry, sandy, or rocky soil has poor thermal conductivity, reducing the efficiency of heat exchange between the ground loop and the surrounding earth.

What is the purpose of a crankcase heater on a heat pump compressor?

Answer: To prevent refrigerant from migrating into and mixing with compressor oil during the off cycle

Crankcase heaters keep the compressor oil warm during off cycles, preventing refrigerant from condensing and mixing with the oil, which could cause compressor damage on startup.

In a multi-zone mini-split heat pump system, what happens if one indoor unit calls for heating while another calls for cooling simultaneously?

Answer: On a standard multi-split, the system serves the majority mode; on a heat-recovery multi-split (VRF), both can be served simultaneously

Standard multi-split systems cannot simultaneously heat and cool, but heat-recovery VRF systems can transfer heat from zones needing cooling to zones needing heating at the same time.

What does a high EER (Energy Efficiency Ratio) value on a heat pump indicate?

Answer: The unit provides more cooling output per watt of electrical input at a specific test condition

EER measures cooling efficiency at a single test condition (typically 95°F outdoor / 80°F indoor), with higher values indicating more BTUs of cooling delivered per watt consumed.

Which heat pump system configuration is MOST appropriate for a building that requires process cooling year-round regardless of outdoor temperature?

Answer: Water-source heat pump connected to a cooling tower and boiler loop

Water-source heat pumps on a shared loop with a cooling tower can reject heat effectively year-round without being dependent on outdoor air temperature, making them ideal for year-round cooling loads.