Forced Hot Water Heating System – Why Its The Way To Go

Introduction – Forced Hot Water Heating

Forced hot water heating systems, also known as hydronic heating, is a type of home heating system that uses water or a mixture of water and antifreeze such as glycol as the transfer medium to distribute heat throughout the home.

It is typically used in homes where the climate is too cold for traditional air-source heating systems. In this article, we will explore why it turns out that hydronic heating systems provide a small but consistent cost savings over traditional air-source heating systems, all other factors being equal.

Radiators are the most visible part of a forced hot water or hydronic heating system

Set-Up Of Forced Hot Water Vs Air Heating

The setup of hydronic and forced hot air systems is fundamentally different. While forced hot air systems rely on air ducts to distribute the heated air throughout the home, hydronic systems use water or a mixture of water and antifreeze to distribute heat.

This means the components of a hydronic system and a forced hot air system are also different. A hydronic system typically consists of a boiler, pumps, pipes, and radiators, while a forced hot air system typically consists of a furnace, air ducts, and a blower.

Forced Hot Water Systems Are Slightly More Efficient Than Forced Hot Air Systems

Hot water and hot air are two of the most common systems employed in residential homes. Though both systems provide warmth, there are distinct differences in fuel efficiency and delivery efficiency that must be taken into consideration.

Fuel Efficiency

Fuel efficiency is an important factor when considering the cost of operating a heating system. Fuel efficiency is a measure of how efficiently a vehicle or heating system uses energy.

It is expressed as a ratio of the amount of energy used to the amount of energy produced. In heating systems, fuel efficiency is measured by the amount of energy used to produce a certain amount of heat. A more efficient system will use less energy to produce the same amount of heat.

In modern systems, that is, as of 2023, the two systems have very similar fuel efficiencies commonly exceeding 92-93%. This is true for different fuel sources such as natural gas, oil, and electricity. Therefore, there is no difference in fuel efficiency. Which brings us to another kind of efficiency.

Delivery Efficiency

Delivery efficiency is the second important factor in determining the cost of operating a heating system. Delivery efficiency is a measure of how efficiently a heating system delivers heat to the desired area. Sometimes the term “distribution efficiency” is used interchangeably.

Forced hot water systems have a higher delivery efficiency rate than forced hot air systems. This is because the water experiences little loss as it moves along a pipe. The loss is estimated at 2.5-5.0%.

In contrast for a forced hot air system there is air loss along ducts which ranges from 3.0% for sealed ducts to as high as 15.0% for unsealed ducts.

The delivery efficiency difference is the main source of the cost difference. To be concrete, that might translate to annual heating cost of $2,400 for a forced air system and $2,100 for a forced water system.

Parts Of A Forced Hot Water Heating System

In more detail, we describe the four parts of a hydronic heating system.


The boiler is the heart of the hydronic heating system. It is responsible for heating the water or mixture of water and antifreeze that is used to distribute heat throughout the home.

The boiler is typically powered by natural gas, propane, or electricity. There are in fact, many types of boilers for a home – which we note just in case you think choosing one is simple. You get to choose the complexity but also the fuel source.


Not all hydronic systems have pumps however they do make the circulation much better. The pumps in a hydronic system are responsible for circulating the heated water or mixture of water and antifreeze throughout the home.

The pumps are typically powered by electricity and are designed to operate quietly and efficiently.


The radiators in a hydronic system are responsible for transferring the heat from the water or mixture of water and antifreeze to the air in the home.

The radiators vary in size, depending on the size of the home, and are typically made from cast iron or aluminum.

Zoned Heating

Zoned heating is an option available with hydronic systems that allows for different areas of the home to be heated to different temperatures. This is accomplished by using multiple pumps, boilers, and radiators, which are controlled by a central thermostat.

This allows for efficient heating of different areas of the home, resulting in greater comfort and cost savings.

How To Transition to a Forced Hot Water Heating System in Your Home

  1. Initial Assessment: Begin by identifying your home’s current heating system and your reasons for wanting to switch. Is it for increased efficiency, lower operational costs, or better heating?
  2. Expert Consultation: Reach out to professionals for an in-home evaluation. They’ll provide insights into the feasibility and advantages of switching to a hydronic system, along with a ballpark estimate of costs.
  3. Old System Removal: Before the new installation, your existing heating system must be decommissioned and safely removed. This is typically done by the same service installing the new system, often at an extra charge.
  4. Boiler Selection and Installation:
    • Boiler Selection: Choose a boiler based on your heating needs and available fuel sources (e.g., natural gas, electricity). This is a crucial step and will be guided by the professionals you consult.
    • Installation Phase 1: The old system is removed, and initial work begins to install the new boiler.
    • Installation Phase 2: Piping is laid down to connect the boiler to where the radiators will be placed.
    • Installation Phase 3: Radiators are then installed in the designated areas.
    • Installation Phase 4: Finally, the system is connected, and water is introduced into the pipes. The system is then activated to ensure it works as expected.
  5. Maintenance Plan: Ask your installer about the recommended maintenance schedule and any warranties. Regular upkeep is simple but crucial for system longevity.
  6. Cost Consideration: The final cost will be a sum of the new system components, labor for both the removal of the old system and installation of the new one, and any initial maintenance or additional parts.
  7. Follow-Up: After the system is running, you may wish to monitor its performance for the first few months to ensure you’re experiencing the benefits you expected.

Maintenance And Care Of A Forced Hot Water Heating System

Regular maintenance is essential for the proper functioning of a hydronic heating system. It is important to have the system inspected by a professional technician at least once a year to ensure that all components are functioning properly and to identify any potential issues.

Replace the filters in the system on a regular basis to prevent debris from building up and clogging the system.

Diagnose issues by a professional technician. The technician will be able to identify the source of the issue and provide a solution to resolve it.

Troubleshoot the issue before attempting to repair it. This can be done by checking the thermostat, inspecting the radiators, and checking the filters.

Contact a professional technician for assistance if troubleshooting doesn’t resolve the problem.

Factors to Consider for Efficiency

When evaluating the efficiency of forced hot water and forced hot air heating systems, consider various factors that contribute to the overall efficiency and cost-effectiveness of the system. Here are some of the main considerations, some of which we’ve already alluded to.

1. Fuel Technology

The type of fuel your heating system uses can significantly impact both its efficiency and cost-effectiveness. Here are some common options:

  • Electricity: Electric heating systems are generally highly efficient in converting electricity to heat. However, the cost per unit of heat generated can be high, depending on local electricity rates.
  • Natural Gas: Natural gas systems may be less efficient in terms of energy conversion compared to electric systems, but they often provide more heat per dollar spent on fuel, making them cost-effective in many cases.
  • Heat Pumps: These systems are highly efficient as they transfer heat rather than generate it. They can also be powered by renewable energy, making them an eco-friendly option. However, the initial installation cost can be high.

2. System Losses

Different systems have varying levels of energy loss, which can affect their efficiency:

  • Air Loss in Forced Hot Air Systems: These systems can experience air loss along the ducts, ranging from 3.0% for sealed ducts to as high as 15.0% for unsealed ducts. This loss can significantly impact the system’s overall efficiency and cost-effectiveness.
  • Minimal Loss in Forced Hot Water Systems: In contrast, forced hot water systems experience little loss as water moves along the pipes, estimated at 2.5-5.0%. This contributes to their higher delivery efficiency.


In conclusion, forced hot water heating systems, also known as hydronic heating systems, offer a slight cost advantage over forced air systems but are otherwise very similar.

Staff Writer
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