How does a heat pump work? Step-by-Step Heating, Cooling Explained

How do heat pumps work? in all heat pumps same basic principle of operation, air source use of heat pump outside air As a heat sink, geothermal use heat pump land As a heat sink. Here we will answer this major question in the simplest terms:

“What is a heat pump and how does it work?”

A heat pump is an HVAC device that transfers heat from one place to another (outdoor to indoor, indoor to outdoor). Basically, it can work as both an air conditioner (transfers heat from indoor to outdoor) and a furnace (transfers heat from outdoor to indoor).

This makes it very useful (you can use 1 device instead of 2) and extremely energy-efficient. heating up and cooling down Huge drop in electricity bills (According to United States Department of Energy, “Geothermal heat pumps can reduce energy use” by 30%-60%,) because you don’t have to use electricity to create heating/cooling; you only use electricity Transfer heating Cooling.

pay attention: Recently, we have seen a significant increase in heat pump sales in the UK due to the Domestic Renewable Heating Incentive (RHI) UK Government heat pump grant. You can read more about this encouragement here,

There are two conflicting concepts here that make us immediately think about how heat pumps work:

  1. How can a heat pump heat in the winter? It transfers heat from outside air (say 14°F or -10°C) to warmer indoor air (+70°F or +20°F):
  2. How can a heat pump cool down in the summer? Outdoor air temperatures can exceed 86°F or 30°C in summer; How could this transfer use that high temperature air to cool the air inside below 68°F or 20°C?

It all has to do with the principle of operation called ‘reverse-cycle conditioning’ facilitated by Refrigerant moving from outdoor to indoor unit, we’ll take one systematic step-by-step approach To explain how all 3 heat pump mechanisms work, namely:

  1. How does a heat pump work in winter? (respectively heating clarification,
  2. How does a heat pump work in summer? (respectively cooling clarification,
  3. We’ll also cover the all-important (yet often overlooked) defrost cycle Which is necessary to protect the heat pump in winter.

We will see that the principle of operation of all heat pumps is based on reverse-cycle conditioning. Understanding this principle helps us understand how a mini-split air-source heat pump works and how geothermal heating works (basic principle, separate heat sink).

How does a heat pump work in winter? (heat cycle)

Heat pump heating cycle using outside air or ground a . as does moderate temperature source, extracts heat from it, and transfers it high temperature Heat in indoor air. Or rather, the heat cycle warms us in winter.

Now, before we look at how a heat pump works step-by-step in winter, let’s clear one thing out of our way:

How can a heat pump use cold outside air (14 °F or -10 °C) to heat the already hot indoor air (70 °F or 20 °F)?

The important part here is to understand that a heat pump or physicist sees air as ‘cold’ or ‘hot’. Hot the wind is only with the wind high temperature material, and cold air is just air a little heat Subject.

How does an external heat pump unit work?
It is an external unit of an air-source heat pump. In winter, it extracts heat from the cold air, and transfers it indoors.

This means that the point of the heat pump heat cycle is to extract available heat from the cold outside air, and transfer it indoors.

How does an external heat pump unit work?
This is an indoor unit (or air handler) of an air-source heat pump. In winter, cold air blows to heat your home.

Here’s how a heat pump’s heat cycle works in the winter:

Step-by-Step Heating Cycle Explained

  1. soft In low pressure And low temperature liquid state Is circulated in external coil,
  2. Even cold outside air has a higher temperature than this refrigerant. NS Refrigerant absorbs this heat And changes from liquid to gas (or hot vapor).
  3. it is refrigerant gas Compressed by compressor (in external unit); This increases its temperature further.
  4. hot refrigerant is sent to indoor unit Through refrigerant lines (lines that run through the wall and connect the outdoor and indoor unit).
  5. The heated high pressure refrigerant is circulated through the indoor coil.
  6. When cooler room air circulates around these indoor coils, it causes refrigerant for cooling and condense back to the liquid state.
  7. Refrigerant gas condenses back to a liquid state (an endothermic process) heats the indoor air Surrounding the indoor coil, provides the heat needed to facilitate heating.
  8. The air blower fitted in the indoor handle delivers this hot air to our house. we feel like Heating,
  9. The refrigerant has done its job; This is now a. passes through pressure reducing part (we call it a ‘expansion valve’ Which again generates a low-temperature low-pressure liquid-state refrigerant.
  10. Refrigerant comes to outer coil and heats cycle starts again,

You can use this example to help you understand the inner workings of heat pumps:

How does a heat pump work in winter

heat pump case Heating, we see that Outdoor act as coils evaporator Coil. inside the house serve as coils in air handlers condenser Coil.

heat pump case cold, Outdoor act as coils condenser coil, and inside the house act as coils evaporator Coil.

Thus any heat pump – air source, geothermal, Water Source – Generate heat and transfer it indoors with smart use of refrigerant liquid-gas transformation.

pay attention: The heat given off by a heat pump is transferred to what we call ‘heat sink, In the case of heating, indoor air is the recipient of heat or ‘heat sink’; We are heating our house. In the case of cooling, we take the heat out of the indoor and transfer it to the outdoor heat sink; outside air (air source), ns land (geothermal), Or Water (Water Source),

Let’s see how the cooling cycle works in a heat pump:

How do heat pumps work in summer? (cooling cycle)

As you can imagine, to provide cooling rather than heating, the direction of heat transfer is reversed, The heat pump has a heating-to-cooling switch that reverses this. You can easily control this via the heat pump thermostat.

Here’s a step-by-step description of how a heat pump works in the summer:

  1. Switch the heat pump thermostat to ‘Cooling’. This Activates the reversing valve, switches the direction in which the compressor pumps the pump, and defeat refrigerant flow,
  2. indoor coil squeeze Heat from indoor air. The liquid refrigerant is converted from indoor heat to the gaseous state.
  3. Hot refrigerant gas vapor is fed into the outdoor unit through refrigerant lines,
  4. In the outer coil (now acting as the condensation coil) the hot refrigerant is cooled, dispel indoor heat on the road,
  5. The compressor then squeezes the refrigerant into a liquid low-pressure low-temperature liquid state.
  6. liquid refrigerant starts re-cooling cycle,

This is the basics of how the heat pump cooling cycle works.

In summer, it’s hot outside, and we don’t have problems with the outside coil freezing up. However, if you examine how the heat pump works in summer versus winter, you will see that in winter, outdoor coils can freeze,

This is why every heat pump has a third mechanism of operation that defrosts potentially frozen on the outside coil. This operating mechanism is known as ‘defrost cycle’,

Defrost cycle (important feature in winter)

In winter, we have lower outside temperatures. If the temperature is too low and the relative humidity is high enough, the heat pump outdoor coil may freeze. we will notice it like this frost on the surface of the outer coils,

Frozen coils will reduce the energy efficiency of the heat pump and can cause all kinds of negative residual effects. This is because the ability of the outer coil to transfer heat is hindered.

How the Heat Pump Defrost Cycle Works
In winter, this brown ice can form on the outer coils. If the coils are frozen, they will not transfer heat efficiently.

To melt the frost on the outer coils in winter, heat pump temporarily Switch from heating mode to cooling mode (Cooling mode heats the outer coil). This is known as the ‘defrost cycle’.

You should be aware of this defrosting cycle because, for some time, a heat pump set to ‘heating’ in winter will blow cold air indoors. there is nothing wrong When this happens with your heat pump; In fact, this is standard operating procedure for heat pumps in winter.

This explains how the Mini-Split Air-Source Heat Pump works.

Let’s take a look at how a ground source heat pump works:

How does a ground source heat pump work? (vs wind-source and water-source)

All heat pumps work on the same principle. What is the difference between the way ground source, air source and water source heat pumps work?

The only difference in how different heat pumps work is where they are. transfer heat To (summer) and where they transfer heat From (cold). This, in itself, can make a big difference when deciding which type of heat pump is best for your situation.

Let’s look at the 3 types of heat pumps and their heat transfer:

  1. air source heat pump transfer heat from outside air, outside air changing temperature, cold in winter, warm in summer; This is a thief. Because of changing outside air temperatures, air-source heat pumps work best in areas with temperatures above 30ºF or -1ºC. Nevertheless, they are easy to install, are cheaper than other types of heat pumps, and are most popular types of heat pumps,
  2. ground-source heat pump transfer heat from land, Base temperature is constant (usually around 55ºF or 13ºC in the UK); This is great news for how geothermal heating works. This means that in winter, a geothermal heat pump will be able to extract more heat from the cold outside air than an air-source heat pump will. This also means that ground-source heat pumps are most energy efficient and cost-saving type heat pump. However, they are expensive to install.
    How does a ground source heat pump work?
    Geothermal heat pumps work by extracting heat from the ground. They can use that heat to heat indoor air, either directly or indirectly through radiators (heats the water, which in turn heats the air).
  3. water source heat pump transfer heat from Water, Water temperature is less constant than ground temperature but much more constant than outside air temperature. maintain water temperature rather stable, compensates for seasonal temperature changes (during winter, summer) affecting air-source heat pumps.

Overall, the way ground-source heat pumps work by harnessing the advantage of a constant ground temperature makes them the most energy-efficient type of heat pump.

Hopefully you now understand how heat pumps work. If you have any questions, you can use the comments below and we will try to help you as much as possible.


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