Heating with an air conditioner or gas: which costs less?

Heating with an air conditioner can cost less than heating with gas, but it depends on your energy prices and the efficiency the unit actually achieves. A reversible Mitsubishi Heavy Industries air conditioner can be worth trying for the room you use most, especially if it is already installed. Compare the cost of the same amount of useful heat before deciding to turn down the boiler.

This guide explains the calculation, what can change the result in winter, and how MyAirco helps you control a compatible Mitsubishi Heavy Industries unit. The euro amounts below are illustrative assumptions, not current tariffs, measured savings or a promise about your home.

Why an air conditioner can heat economically

A reversible split air conditioner is an air-to-air heat pump: it moves heat from outdoors into the room. Energy Saving Trust explains this type of heating and why a system intended for winter use needs to be sized for the home's heating demand.

The useful comparison is heat delivered, not just the price of one unit of electricity versus one unit of gas. COP, or coefficient of performance, is heat output divided by electricity input under particular operating conditions, as defined by ENERGY STAR. At COP 3, 1 kWh of electricity supplies 3 kWh of heat. That is a ratio, not a guaranteed efficiency for every hour.

Air conditioner versus gas: a worked cost example

Use the variable prices on your own energy bill, including taxes. For this example, assume electricity costs €0.30/kWh, gas costs €0.12/kWh of fuel, and the gas heating system delivers 90% of that fuel energy as useful room heat. The 90% is an assumption; use an efficiency estimate appropriate to your installation and the same energy basis as your gas bill.

If your gas bill is in cubic metres, first convert it using your supplier's kWh-per-m³ factor. For illustration only, €1.20/m³ divided by an assumed 10 kWh/m³ gives €0.12/kWh. The factor 10 is not universal: gas composition and billing conventions vary.

At COP 3, the example saves €33.33 per 1,000 kWh of useful heat, or 25% of the variable gas-heating cost. At COP 2, the air conditioner is more expensive. Neither result describes your total energy bill: gas used for hot water, standing charges and other electricity use remain separate.

Find your own break-even point

• Air-conditioner heat cost: electricity price per kWh ÷ achieved COP.
• Gas heat cost: gas price per kWh of fuel ÷ heating-system efficiency, written as a decimal.
• Break-even COP: electricity price × gas-heating efficiency ÷ gas price per kWh of fuel.

With the example prices: 0.30 × 0.90 ÷ 0.12 = 2.25. Above COP 2.25, the air conditioner delivers cheaper heat; below it, gas is cheaper. If you have hourly electricity prices, the threshold changes with the price during the hours you heat.

For a whole season, use an estimated seasonal performance for your climate and installation. Multiplying one mild afternoon's COP by all winter's heating demand gives a misleading result. A solar panel also does not make every winter heating hour free: allow for when electricity is generated, imported or exported.

What about Mitsubishi Heavy Industries air conditioners?

Use the specifications for your exact indoor and outdoor unit combination. For example, Eurovent's certified SRC50ZS-W/SRK50ZS-WF entry lists a standard heating COP of 3.72 and an SCOP of 4.60. Those are different rated measures, not a claim that every MHI unit achieves those figures in your home.

SCOP describes seasonal performance under specified test conditions. Check the stated climate and heating capacity as well as the headline efficiency. Ask your installer how the chosen system performs at your local winter temperatures and whether it can meet the room's heat loss. A cooling capacity printed on a brochure is not a forecast of heating electricity consumption.

Heating can pause during startup or defrost. The MHI Ciara user manual describes this behaviour for those models; check your own manual for the indicators and operating limits. A short pause is not a reason to keep sending new app commands.

Heating one room is different from replacing the boiler

Consider the living room while you work or relax there. If the air conditioner supplies that room's heat and you can reduce gas heating elsewhere, the comparison may be attractive. If both systems keep heating as before, the air conditioner adds another energy load. Compare similar indoor temperatures, occupied hours and weather, rather than one cold week against one mild week.

Milieu Centraal notes that air-to-air heating needs a separate hot-water solution and is not automatically coordinated with central heating. A warm living room can also satisfy a centrally located thermostat while other rooms still need heat. Review zoning and thermostat settings with your installer, and keep adequate warmth and ventilation throughout the home.

If you are buying equipment, include installation, maintenance and any changes needed in other rooms. Standing charges normally remain while you keep a gas connection. Do not calculate a payback period from the example table alone, or count summer cooling as a winter saving. For an existing unit, the immediate question is simpler: which system should supply the next hour of useful heat?

Use MyAirco for a repeatable heating setup

MyAirco is an independent Android app for supported Mitsubishi Heavy Industries air conditioners with a WF-RAC or WF-RAC-HTTPS Wi-Fi adapter. Mitsubishi Electric is a separate brand and is not supported. Check compatibility before buying the app; heating efficiency alone does not establish compatibility.

1. Open the right roomConnect your phone to the same home network as the unit. Use clear room names so you change the intended air conditioner.
2. Choose HeatSet a comfortable target, for example 20°C as a starting point, and begin with automatic fan speed. Raising the temperature while still in Cool does not select heating. The MHI heating-mode guide explains the controls.
3. Let the room settleAdjust the target or airflow one step at a time. Judge comfort where you sit and keep the outlet clear.
4. Save a heating favouriteAfter the changes finish, open Favourites at the top right of the control screen, choose Save current settings and give it a name such as “Living room heating”. Apply it manually next time; favourites are not timers or weekly schedules.

MyAirco provides local controls; it does not measure energy consumption or COP, calculate your savings, or automatically switch between gas and electricity. Use your energy bills and suitable metering to assess costs. If the unit cannot be reached, follow the connection troubleshooting guide.

How to decide for your home

Start with your actual tariffs and an efficiency estimate for the installed system, then check the break-even calculation. Try a comfortable, repeatable heating setup in the room you use most and compare energy use over similar conditions. A Mitsubishi Heavy Industries air conditioner may reduce the variable cost of heating that space; MyAirco makes its daily controls accessible from your phone.

Sources checked on 27 October 2026. The calculations are MyAirco editorial examples using the assumptions stated above. They are not a field test, an energy-price forecast or a manufacturer savings guarantee.