How Does a Heat Pump Work? — Complete Guide for Indian Homes (2025)

A heat pump works by extracting heat energy from the surrounding air and transferring it to water or indoor spaces — using up to 5× less electricity than a conventional electric geyser. Unlike a heater that generates heat by burning fuel or resistive coils, a heat pump simply moves existing heat, making it the most energy-efficient water heating technology available in India today.

Every Indian household is familiar with the electric geyser — and the steep electricity bills that come with it. Heat pumps solve exactly that problem. In this guide, we break down the working principle of a heat pump in plain language, explain each key component, and show you why millions of Indian homes are making the switch.

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How a Heat Pump Works — Step by Step

A heat pump follows a continuous thermodynamic refrigeration cycle. Here are the 6 core steps:

1. Air intake — The outdoor unit draws in ambient air (even at temperatures as low as –7°C) using a large fan.
2. Evaporation — A cold liquid refrigerant (typically R-410A or R-134a) flows through an evaporator coil. The ambient air is warm enough to cause the refrigerant to evaporate into a low-pressure gas, absorbing heat energy from the air in the process.
3. Compression — The low-pressure gas is passed through a compressor, which raises its pressure and temperature significantly — typically to 60–80°C.
4. Heat exchange (condenser) — The hot, high-pressure gas flows through a heat exchanger (condenser coil) that surrounds the water storage tank. Heat transfers from the refrigerant into the water, heating it to the desired temperature (usually 55–65°C).
5. Expansion — The now-cooled refrigerant passes through an expansion valve, dropping its pressure and temperature back to the starting point.
6. Cycle repeats — The cooled liquid refrigerant re-enters the evaporator and the cycle continues until the tank reaches its set temperature.

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Key Components of a Heat Pump — Explained

Understanding the four main components helps you evaluate performance specs when choosing a model:

Component	Function	What to Look For
Compressor	Raises refrigerant pressure and temperature	Inverter compressor = variable speed, quieter, more efficient
Evaporator Coil	Absorbs heat from ambient air into refrigerant	Larger coil surface area = better performance in mild winters
Condenser Coil	Transfers heat from refrigerant to water	Titanium or stainless steel coil resists corrosion in hard-water areas
Expansion Valve	Reduces refrigerant pressure to restart the cycle	Electronic expansion valve (EEV) offers finer efficiency control
Refrigerant	The fluid that carries heat through the system	R-32 or R-134a — lower global warming potential, legal under Indian norms

Tip: When comparing Hyundai heat pump models, check if the unit uses an inverter compressor — inverter technology automatically adjusts output based on ambient temperature, delivering 15–20% better efficiency than a fixed-speed compressor, especially on mild Indian winter mornings.

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What Does a Heat Pump Run On?

A heat pump runs on electricity and a refrigerant. It does not burn gas, LPG, or solar energy directly. The electricity powers the compressor and fan; the refrigerant is the medium that carries heat. Because it moves heat rather than generating it, a heat pump delivers 3–5 units of thermal energy for every 1 unit of electrical energy consumed — a ratio known as the Coefficient of Performance (COP).

For context: a standard electric geyser has a COP of 1 (1 unit of electricity = 1 unit of heat). A Hyundai heat pump water heater achieves a COP of 3.5–5.0 depending on the ambient temperature — meaning it delivers up to 5× more hot water for the same electricity spend.

Can a heat pump run on solar? Yes — heat pumps are fully compatible with rooftop solar PV systems. Many Indian homeowners pair a Hyundai heat pump with a solar array to bring their effective electricity cost for hot water production close to zero.

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Heat Pump Working Principle — In Simple Terms

If technical diagrams aren't your thing, here's the simplest analogy:

"A heat pump works exactly like your refrigerator — but in reverse. Your fridge pulls heat out of food and dumps it into your kitchen. A heat pump pulls heat out of the outdoor air and dumps it into your water tank."

That is the entire principle. The outdoor air — even on a cool 10°C January morning in Delhi — contains more than enough heat energy to warm a 200-litre tank to 60°C. The heat pump's job is simply to collect that energy efficiently and concentrate it where you need it.

Key takeaway: heat pumps don't create energy — they relocate it. That's why they are so dramatically more efficient than resistive heaters.

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Heat Pump vs Electric Geyser — Quick Comparison

Factor	Heat Pump	Electric Geyser
Working principle	Moves heat from air to water	Generates heat via resistive coil
COP (efficiency ratio)	3.5 – 5.0	1.0
Monthly electricity cost*	₹300 – ₹500	₹1,200 – ₹2,000
CO₂ footprint	Low (uses ambient energy)	High (100% grid electricity)
Initial cost	₹35,000 – ₹1,20,000	₹5,000 – ₹18,000
5-year total cost	Lower	Higher (2–3× running cost)
Works in Indian climate?	Yes (–7°C to 43°C)	Yes (any temperature)
Installation complexity	Medium (outdoor unit needed)	Low (wall-mount)

* Estimate based on 200L/day usage at ₹8/unit electricity. Actual savings vary by region and tariff slab.

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Frequently Asked Questions

How does a heat pump work in winter?

A heat pump can extract heat from outdoor air down to approximately –7°C, which covers all major Indian metros including Delhi and Shimla during winter months. At lower ambient temperatures, the COP drops slightly — from ~4.5 in summer to ~3.0 in a cold winter — but the unit continues to function and still outperforms an electric geyser in efficiency.

What is the heat pump working principle called?

It is called the vapour-compression refrigeration cycle or reversed Rankine cycle. The same thermodynamic principle powers your air conditioner, refrigerator, and industrial chillers — heat pumps simply apply it in reverse to deliver heat rather than cold.

Is a heat pump the same as an AC?

Technically, yes and no. Both use the same refrigeration cycle. However, an AC is optimised to cool indoor air and reject heat outdoors. A heat pump water heater is configured to capture that rejected outdoor heat and use it to warm water. Some multi-function heat pumps can both heat water and cool indoor air simultaneously.

How much electricity does a heat pump use per day?

A Hyundai 200-litre heat pump water heater consumes approximately 1.0–1.5 kWh per day to produce 200 litres of 60°C water — compared to 4.0–5.0 kWh for an equivalent electric geyser. Annual savings typically range from ₹12,000 to ₹24,000 depending on your electricity tariff and usage volume.

Does a heat pump work without sunlight?

Yes. Unlike solar water heaters, a heat pump does not require direct sunlight — it draws energy from ambient air temperature. This makes it reliable year-round, including during monsoon and overcast winter days when solar heaters underperform.

What refrigerant does a heat pump use?

Modern Hyundai heat pumps use R-32 or R-134a refrigerants — both of which have significantly lower global warming potential (GWP) than older R-22 refrigerants and comply with India's current HFC regulations under the Kigali Amendment schedule.

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