Everything You Wanted To Know About Hydronic Heating

Everything You Wanted To Know About Hydronic Heating

Anthony Barnes

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A hydronic heating system uses water as a medium to transfer heat. It heats the liquid inside its system, then distributes the heated liquid through pipes. You can install heating systems in the floors, or use baseboard hydronic heaters or radiators. 

Floor heating can also be installed in the foundation, or over existing flooring. Prefabricated panels can be used for radiant flooring.

Everything You Wanted To Know About Hydronic Heating

Hydronic Heating System: The Benefits

Hydronic heating is an efficient solution to heating your home. You won’t have any hot or cold areas. Your home will stay nice and cozy when it gets cold out.

Hydronic systems use water as a heat source. A hydronic system uses pipes to circulate hot water throughout your house. You may choose to install a forced-air system if you prefer to be more independent of the weather.

Hydronic heating systems are great because you can control the temperature in different parts of your house. You can set different temperatures for different rooms. It doesn’t matter if your door is open or not because the system doesn’t use air flow.

Radiant heating systems use a liquid in a closed system. This means that humidity levels are not a concern. You won’t be affected by any changes in humidity.

Radiant flooring helps to keep your floors cool. That’s especially nice when you’re getting up early in the morning. Below the floor, tubes spread heat and the whole floor is a conductor to make everything warm.

Radiant heating systems are not loud. There is no sound like when a heater is switched on or the creaking and groaning sounds made when warm air travels through cool air ducts, you don’t hear the rush of warm air that forced-air systems force out.

Hydronic systems don’t need air ducts and return-air systems. Retrofitting them takes up a lot of space. You can install hydronic system tubes anywhere you want – under floors, behind walls, etc.

Hydronic heating systems are quiet and clean because they don’t use ducts. Forced-air systems trap large particles with air filters. Hydronic systems don’t need furnace filters.

Boilers are more consistent than furnaces. They also give off less smoke. Furnaces use moving air to heat the house, which means they pick up dirt and bacteria along the way. A boiler heats the water directly, so there is no moving air to carry these things around.

Energy Efficiency

Hydronic heating systems are more effective than alternative heating methods because air doesn’t conduct heat very well. A hydronic system uses hot water instead of air to transfer heat throughout your house. This method requires less energy than other methods.

Also, water retains heat much better than air. So, when your boiler runs, it won’t only be more efficient, but it’ll keep you warmer for longer. Also, there’s no heat loss due to leaking ductwork, which accounts for up to 30% of wasted energy with forced air furnaces.

You can save money with radiant heat systems to keep your house warm. The boiler ensures you feel comfortable and saves money—a perfect comfort combo.

Not Just Warmer, But More Even Heating Too

Radiant heating is warmest close to the floor. Heating systems are also installed closer to the ground, making them easy to install. They don’t push out cold air, so there are fewer drafts.

Hydronic systems are commonly used in radiant floor systems, baseboards, or radiators. Forced air systems are generally at a distance, making them a poor choice for radiant floor heating.

Forced air heating systems use air displacements to keep you warm. These systems move air briskly and the drafts and breezes may cause uneven heating or cooling around the house. Hydronic heating systems eliminate this issue. Radiation keeps you warm without drafts and breezes.

How Hydronic Heat Works

Boilers use conduction to heat the liquid inside them. Boilers heat but do not boil water. Water is dispersed as either hot liquid or as steam through pipes to radiating tubes, coils, or radiant floors. Hot water circulates through the pipes, heating up everything it touches.

Radiators radiate heat into the room, while hydronic baseboards heat (see also ‘Baseboard Heating Vs Forced Air‘) up the floor.

Hydronic radiant heating systems use hot water or steam to warm up homes. Multiple energy sources are available. You can choose what power source you want. Boilers heat water using gas, oil, electricity, or other fuels. Heat exchangers (see also ‘How Do I Know If My Furnace Heat Exchanger Is Bad?‘) transfer the heat from the hot water or steam into the air inside the house.

General Info About Hydronic Heating & Boilers

Boilers disperse the heated water into radiators, coils, and radiant floor systems. You can choose what type of fuel source you want to power your boiler. If you have a preferred fuel source in mind, let your technician know.

Boilers heat your home more consistently than furnaces. Furnaces pump hot air through ducts to heat your home. This creates an unhealthy environment that can lead to respiratory issues. With a boiler, there is no moving air, so you avoid these health risks.

Water is better than air because it holds heat energy much better. When your boiler runs, not just is it more efficient, but it also keeps people warm for longer. There‘s also no heat loss through leaky ductwork, so you won‘t pay for heating that isn‘t needed.


Hydronic Heating & Boilers

A hydronic heating system consists of a number of important components. The boiler is the center of the system and warms up the liquid. The thermostat controls the temperature and turns the system on/off.

Manifolds direct the water flow in the plumbing system. Tubes carry the liquid medium. A heat exchanger transfers the hot water into the house. A pump pushes the heated fluid through the pipes.

A good, efficient boiler is an essential part of any hydronic heating system. It will help you save money on your utility bills and reduce your carbon footprint.

A solar water heater is an option for an efficient heating method that uses solar power to create hot water. Another is a heat pump – a type of heating device that uses the Earth’s thermal energy to warm up cold water.

Hydronic heating systems use hot water as the working fluid. Traditional systems use hot water, but newer systems can also use antifreeze solutions.

Floor heating systems are the easiest type of hydronic heating system to install. They are also used by many people because they are easy to maintain and clean. Wall and ceiling heating systems are less popular because they require more work to install and maintain.

Disadvantages Of Hydronic Heating

Hydronic heating systems work by circulating hot water around the house. The water heats up as it travels through pipes and radiators. You’ll have to wait to feel the heat because the water circulates throughout the entire building.

Baseboard hydronic systems require more space than traditional forced air systems. Hydronic heating systems use pipes to move heat around your house. These pipes can be large and difficult to install. They can take up space and be unsightly. You may have to tear up flooring or walls if you install these systems.

All closed loop water heating systems need an Expansion Tank for safety. This maintenance task is one that all hydronic heating systems require. However, it’s easy for them to get overlooked, causing inefficient operation.

Hydronic heating systems pose a threat to your house if there is a pipe leak or burst. You should be aware of these problems before you buy a new home. Repairs are hard and expensive.

Installing a hydronic heating system into an already built home is expensive. You will need professionals to help install it. Removing the floor or drywall yourself is less costly than installing the system, but it can be a very difficult job if you’re not experienced.

Radiant heating and cooling systems aren’t as common as other types of heating and cooling systems. Since they’re less common, they cost more than traditional methods. Installing two separate systems for heating or cooling costs more money than using a single system.

Hydronic heating systems require extensive planning because you need to make sure that the heating elements are close to the floor. Heat radiates outwards, but if there isn’t enough space around the heater, then the heat won’t reach the desired areas.

Radiant heating heats objects by radiating heat. Objects need to be in the direct line of sight for them to work efficiently. Furniture pulled up against the walls, or thick carpets can lower the heating abilities of the system.

You might have worse air circulation with these systems. You should open up windows and doors in your house to improve the air quality inside. Stagnant air leads to bad smells and pollution. Opening up windows and doors allows fresh air to circulate inside your house.

Potable Water

Combined space and water-heat installations where the plumbing system shares a heat source and water are allowed in certain circumstances. These arrangements can reduce the up front costs of installing a small radiant heating system (up to 50kW).

However, there are risks associated with such systems. A designer or installer should be aware of them before proceeding.

Installing a hydronic heating system with potable water may cause potential health and safety issues if you don’t know what you’re doing. Radiators, pipes, fittings, fan coils, and valves aren’t always designed for potable water. Expansion tanks (see also ‘Expansion Tank Installation‘) and distribution manifolds are also not recommended for potable water.

You need to check whether any of these components are made out of brass alloy. Brass is an alloy of copper and zinc, and also can contain lead. Lead is toxic when ingested. If you see the word “non-potable” written next to the name of a component, it means that this component is not meant for potable water.

Any component that comes into contact with potable water must be tested and approved for use in potable systems. In order to prevent leaks and failures, you should check that your components are suitable for use with potable fluids. 

For instance, if you’re installing a mixing valve in a new installation, make sure that it’s been tested and certified for potable fluid use. You also need to ensure that the fittings used to connect the valves are appropriate for potable fluid usage.

Bacteria called legionella causes a deadly lung infection called legionnaires’ disease. These bacteria live in both potable and industrial water systems, especially where there is stagnant water between 95 F (35 C) and 122 F (50 C). Legionella can be spread by breathing contaminated air or by drinking contaminated water.

The disease was named after the first outbreak of this illness, which occurred among American Legion members attending a convention in Philadelphia in 1976. In recent years, many people have died from this type of pneumonia. Plumbing companies must take precautions to prevent this dangerous disease from spreading.

A potable hydronic heating system with a shared water tank should have a device that prevents stagnation of potable water. The device must ensure that potable water is mixed with heated water at least once per day.

Water systems should be flushed every time there is an outbreak of Legionnaires’ disease. Heating systems should be flushed when the water reaches 160 degrees Fahrenheit. Radiant heaters should never be used for flushing water systems.

Comparison With Electric Radiant Heating

Radiant heating systems make use of either hot water or electricity to heat your home. Electric radiant heating costs less than hydronic radiant heating, but both options require installation by professionals. Hydronic radiant heating is generally easier to install than electric radiant heating, but requires more maintenance over time.

Radiant heating systems use hot water pipes under flooring to provide warmth to the whole house. Traditional furnaces heat the air above the floors, leaving them cold. Radiators heat the air directly, keeping the floors warm.


Hopefully, this guide has helped you to learn about hydronic heating!

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By Anthony Barnes

Anthony Barnes is the founder of Water Heater Hub and a second-generation plumber by profession. Before developing Water Heater Hub, Anthony Barnes was a full-time plumber, and he has undertaken a wide variety of projects over the decades. As a second-generation plumber, it was easy for Anthony to get used to the technicalities of all from a tender age