Air Conditioners and Furnaces: How Do They Work Together?

Your heating and cooling systems have many components that work together to provide optimal home comfort. Air conditioning systems work hand in hand with your heating system, so upgrades to your cooling system will be affected by the efficiency of your heating system.

Air Conditioners and Furnaces - How Do They Work Together?

1. Furnace heats the air in the winter and the blower circulates air through the home
2. AC evaporator coil removes heat and humidity in summer
3. Condensate line carries excess moisture to floor drain
4. Compressor circulates refrigerant through evaporator coil and expels heat outdoors
5. Cool or warm air supplied to the home
6. Thermostat sets temperature for your comfort
7. Air returns to furnace for air conditioning
8. Humidity is added in water
9. House air is cleaned before being recirculated

What is a Furnace?

Most North American homes are kept warm with furnaces, of which there are three main types: natural gas, oil and electric. There are also non-furnace home heating solutions, such as heat pumps and steam heat boilers, which interact with HVAC systems in ways similar to furnaces. Some homes may also have zone heating systems like baseboard heaters, radiant floor heating or wood burning stoves.

How Do Home Furnaces Work?

Furnaces vary in the types of energy they consume, which affects the ways in which they produce heat. But once a furnace creates warm air, it gets distributed the same way, regardless of the energy type. How does a furnace work in a house? Here are the basic steps:

1. When the temperature in the house drops below the thermostat setting for heat, the thermostat sends two signals: one to the furnace to begin a heating cycle, and another to the blower motor to activate the HVAC fan.
2. The furnace’s heating elements receive the signal and activate. In gas and oil furnaces, those fuels are released through valves to produce open flames. In electric furnaces, electricity powers heating elements that are like large versions of the elements in electric space heaters.
3. The heat is transferred to the air. In electric furnaces, this is simply a matter of the exposure of the heating elements to the open air. In gas and oil furnaces, the flames heat a component called the heat exchanger, a sealed chamber that warms the air around it.
4. The blower motor and fan push the warm air through the ductwork and vents, raising the temperature in the home.
5. The thermostat detects the moment when the indoor temperature reaches the desired level and sends signals to shut off the furnace and blower motor.

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These days, everyone knows about air conditioning and how it works to cool your home on hot summer days. But what most people don’t know is your air con works for both heating and air conditioning – and you can link it up with renewable energy.

We’ve put together this short guide to explain how heating and air conditioning can come from one unit. We’ll also explain why it’s an ideal option for your home or office.

How can one unit provide heating and air conditioning?

If you’re clued up on renewable energy, you may have heard of heat pumps. Generally, people think of air- or ground-source heat pumps, which take heat from the air or ground and use this to heat your home. Essentially, this is what air conditioning does – these days, most units are combined, so can offer heating and cooling.

The most common combined heating and air conditioning units used in the UK are multi-split systems, but central air conditioning can also heat and cool your home or business premises. Central units only have one internal unit, meaning you can only heat and cool one area of your property, whereas multi-split systems have at least two, so you can heat or cool different parts of your home or office to different temperatures.

This video explains how air-to-air heat pumps work, which gives you an idea of how combination air conditioning units work:

Heating and air conditioning works by producing heat or cool air through the vapour-compression refrigeration cycle. A chemical refrigerant carries heat from one part of the system to another and then releases it. There are four components in the system that work together to make it happen:

• 1. Compressor: The compressor squeezes a refrigerant, or coolant, and turns it into a hot, high-pressure gas that is then pumped into a condenser.
• 2. Condenser: The condenser is a long-coiled tube that is located in the external unit. The refrigerant moves through it, then the heat dissipates into the environment with the help of a fan. It turns back into a liquid as it cools, and passes into the expansion valve.
• 3. Expansion valve: The expansion valve lowers the pressure of the refrigerant and returns it to a full liquid state before pumping it into the evaporator.
• 4. Condenser: Like the condenser, the evaporator is a long-coiled tube. There’s less pressure in this coil, so the refrigerant turns into a gas and evaporates. It pulls heat from the air to use as energy, which powers the transformation from liquid to gas. The gas absorbs the heat, and a fan blows the cold air it produces around the room.

Once this cycle is complete, the low-pressure gas will return to the compressor so the cycle can begin again.

If it’s a combined air conditioning and heating system, this process can simply be reversed. All that’s needed is a reversing valve, which reverses the flow of thermal energy; the hot condenser becomes the cold evaporator and removes the cold air, pumping the warm air into the room.

What are the benefits of a combined air conditioning unit?

There are lots of benefits to installing a combination heating and air conditioning unit. Of course, the main benefit is that you can heat as well as cool your home. But what about the benefits over other air conditioning systems? Here’s a quick run-down of the advantages of a split or multi-split system:

Climate control

With a multi-split system that offers combination heating and air conditioning, you can control the temperature of different parts of your home or business premises. You can heat or cool different areas as much or as little as you need to, ensuring that you’re always comfortable whatever the weather outside.

Efficiency

Heating and air con systems are efficient. This is mainly because they don’t use ducts to push air around your property. Ducts lose heat on cold days and get warm on hot days, whereas split or multi-split systems use refrigerant pipes and pressure to heat or cool, making it more efficient.

Cheap to run

Combined heating and air conditioning systems are a good option for heating your home, especially if you don’t have a mains gas connection. Electricity powers them, making them cheaper to run than oil boilers. If you’re replacing an old G-rated oil boiler with a new combination heating and air conditioning unit, you could save between £930 and £1,100 per year on your fuel bill. Plus, if you pair a combination air conditioning installation with renewable energy, you could pay next-to-nothing to run your system.

Pair your combination air conditioning system with solar panels

Electricity runs air conditioning systems. That means you’ll pay to run the system from the National Grid, unless you invest in renewable energy.

A great way to reduce your running costs and do your bit for the environment is to power your heating and air conditioning units with solar panels. Solar panels generate electricity from the sun, then distribute this electricity to the appliances in your home. Depending on how many solar panels you get and the amount of electricity you use elsewhere in your home, you could power your air conditioning system for free.

Who needs to carry out a heating and air conditioning service?

Cominbation heating and air conditioning units still have the same components as normal air conditioning units, so an F-gas registered engineer needs to service your unit. If released into the atmosphere, the regfrigerant in a heating and air conditioning unit can be extremely harmful to the environment, so it’s important to have your system serviced by a qualified engineer that can take all the necessary precautions.

During a heating and air conditoning service, the engineer will:

• Check that your system is still heating and cooling efficiently
• Clean indoor and outdoor units
• Inspect air filters, coils, fans, compressors and any other components
• Check all electrical connections
• Test for refrigerant and oil leaks
• Ensure your system is stil compliant with F-Gas regulations

If everything is still working well with your air conditioning unit, it will be a simple and quick appointment. However, if your heating and air conditioning service flags up any problems, your engineer will advise you on what should be done to fix it. If you have regular services, hopefully any problems will be identified and can be fixed easily at relatively low cost. That’s why it’s important to keep up with your services, as they could save you money in the long term.

Get advice before investing in combined heating and air conditioning

It’s best to do lots of research and get some professional advice before buying any type of air conditioning system. At D-Air, we’ll be able to tell you the best system to install in your property based on how big it is, what systems you currently have in place and give you an idea of cost.

Simply fill in the form below to get in touch with us. We’ll give you a free, no-obligation quote for the ideal heating and air conditioning solution for your home or business.