Heating System Guides

Consumer Buying Guides to Home Heating and Air Conditioning Systems

Hot Water Heating Systems

Boilers, or hot water heating systems (hydronic heating) are a very old, proven, and trusted type of home heating system that is still quite popular today. The steam or very hot water that is created within the boiler is circulated through pipes underneath the floor, or through baseboard or standing radiators. The heat from the water or steam radiates out of the pipes to heat the room.

Gas is the most common and economical way to heat water although oil and electricity are also used. Innovations in ground source heat pumps are improving their performance so that excess heat produced can be used to heat water.

Types of Hot Water Heating Systems

There are 2 basic types in use today, steam systems and hot water systems, also known as hydronic heat systems.

Steam Heating Systems – While these are not installed as often today as hydronic systems, there are still many in use. They use a boiler to heat water to the point it turns into steam. The steam is circulated through the pipes into radiators which are used to heat rooms or zones of the house.

The steam cools and condenses there and is pumped back to the boiler to be reheated. The Energy Savers website discusses how a hot water heater works and the complexities of them since they require pressure gauges, relief valves and automatic feeds.

Hot Water or Hydronic Heating Systems – These function in the same way that steam systems do but the water isn’t heated to the same high temperature.

Components of a Hot Water Heating System

Look at these basic components of a typical hot water heating system:

  • Boiler or Furnace
    Using gas, oil or electricity, the boiler is the element that heats the water to the desired temperature.
  • Expansion Tank
    Mounted above the boiler, it allows for the expansion of the water as it is heated.
  • Circulation Pump(s)
    A circulation pump is required to move the hot water through the pipes and back to the boiler.
  • Radiators or Baseboard Heaters
    These may be large standing units but smaller baseboard radiators or convectors are more common and produce more balanced heating. The baseboard units have a fin-type grid attached to the pipe to increase surface area and aid in the dissipation of the heat into the room.
  • Underfloor Coils (Learn more at the Radiant Floor Heating section)
    High-grade plastic tubing is installed on top of the floor deck. Self-leveling concrete is usually used to cover the coils and then various types of flooring are used to finish the floor. The heat from the hot water flowing through the underfloor coils or tubing radiates upward to heat the floor and the entire space.
  • Thermostat(s) – The thermostat calls the entire system into action! When a room or area cools down below the set-point on the thermostat, it will automatically tell the furnace or boiler to start up and heat up the water in the system.

How Hot Water Heating Systems Work

The boiler heats water in a tank using gas, oil or electricity. The steam or heated water is pumped through one or more circulating pipes that take it to radiators, baseboard units, or underfloor coils where it radiates out into the room to heat it. As it cools, the water is circulated back to the boiler to be reheated.

Finally, steam heating systems are being phased out in favor of hydronic or hot water heating systems. These systems are popular because they are quieter than forced air systems and since there is no blower or duct work, they don’t blow dust around the home. Hydronic hot water heating systems are also very efficient and they are easy to maintain.

Potential disadvantages include the fact that air conditioning and healthy ventilation of the home must be accomplished through a separate system. Hot water heating systems are a good choice for homes that don’t require air conditioning or where cooling is achieved through high-efficiency ductless air conditioning systems.