HVAC Heat Pump Technology

Question 1

What is the fundamental operating principle of a heat pump that makes it more efficient than a resistance heater?

Accepted Answer

It moves heat from one place to another rather than generating heat, delivering 2-4 BTU of heat for every BTU of electrical energy consumed

Answer

It generates heat through combustion more efficiently

Answer

It stores solar energy and releases it as heat on demand

Answer

It uses a fuel cell to convert hydrogen into heat with high efficiency

Question 2

What is the 'balance point' of an air-source heat pump?

Accepted Answer

The outdoor temperature at which heat pump capacity equals building heat loss—below this, supplemental heat is needed

Answer

The temperature at which the refrigerant transitions from vapor to liquid phase

Answer

The temperature at which COP equals 1.0, making resistance heat equally efficient

Answer

The minimum outdoor temperature at which the heat pump can operate

Question 3

What is the 'Heating Seasonal Performance Factor' (HSPF)?

Accepted Answer

The total seasonal heating output in BTU divided by total electrical energy input in watt-hours; higher = more efficient

Answer

The maximum heat output in BTU at standard test conditions

Answer

The efficiency at the balance point only

Answer

The number of heating cycles per season

Question 4

How does a geothermal (ground-source) heat pump differ from an air-source heat pump?

Accepted Answer

Geothermal exchanges heat with the ground (stable temperature year-round) via buried loops, achieving higher efficiency than air-source which uses variable outdoor air temperature

Answer

Geothermal uses gas combustion while air-source uses electricity

Answer

Geothermal provides cooling only; air-source provides both heating and cooling

Answer

Geothermal is used only for commercial buildings; air-source only for residential

Question 5

What is a 'reversing valve' in a heat pump?

Accepted Answer

A four-way valve that reverses refrigerant flow direction, switching the system between heating and cooling modes

Answer

A valve that adjusts refrigerant flow rate based on demand

Answer

A pressure relief valve that prevents refrigerant overheating

Answer

A check valve that prevents refrigerant from flowing backward during compressor shutdown

Question 6

What causes 'defrost cycles' in air-source heat pumps and how are they handled?

Accepted Answer

Frost/ice accumulating on the outdoor coil in cold, humid conditions, reducing efficiency; handled by temporarily reversing to cooling mode to melt frost

Answer

Refrigerant ice crystals forming inside the compressor; handled by hot gas bypass

Answer

Ice forming in the refrigerant lines; handled by a heat trace

Answer

Freezing of the indoor coil from overcooling; handled by reducing indoor airflow

Question 7

What is a 'variable-speed' or 'inverter-driven' heat pump and why is it more efficient?

Accepted Answer

A heat pump with a variable-speed compressor that can modulate output from ~25% to 100%, matching actual load and avoiding on/off cycling losses

Answer

A heat pump that can switch between heating and cooling modes

Answer

A heat pump with multiple indoor units

Answer

A heat pump with a variable-speed outdoor fan only

Question 8

What is a 'dual-fuel' or 'hybrid' heat pump system?

Accepted Answer

A system pairing an air-source heat pump with a gas furnace, using the heat pump for mild weather and switching to gas heat when it's more cost-effective at very cold temperatures

Answer

A system that uses two refrigerants simultaneously for improved efficiency

Answer

A system that provides both heating and domestic hot water using two separate refrigerant circuits

Answer

A system with both a ground-source and air-source heat pump for redundancy

Question 9

What is a 'water-source' heat pump (WSHP) and how is it applied in commercial buildings?

Accepted Answer

A heat pump exchanging heat with a common water loop, allowing internal heat recovery between simultaneously heating and cooling zones in a building

Answer

A heat pump using well water as the only heat source, suitable for residential use only

Answer

A heat pump using municipal water supply for condensing, with continuous discharge to sewer

Answer

A heat pump designed only for pool and spa heating applications

Question 10

What is a 'mini-split' (ductless) heat pump?

Accepted Answer

A ductless system with a small outdoor compressor connected to one or more wall-mounted indoor units; advantages include no duct losses, individual zone control, and easier installation in retrofit applications

Answer

A small window-mounted heat pump; advantage is low upfront cost only

Answer

A heat pump serving only a single room; advantage is it can be moved to different rooms

Answer

A split system that uses a mini compressor for reduced refrigerant charge