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Hydronic heating systems – What you need to know

January 14, 2015

A hydronic heating system uses hot water as the method for heating a home.

The water is heated by a boiler or water heater that may use electricity, oil, natural gas or propane as its energy source. The heated water is circulated through a series of pipes to baseboard convectors or radiators located in a room.

Hydronic systems also may circulate the heated water through a fan coil located in a forced air furnace where the heated air is distributed through duct work in your home.


How do hydronic systems work?

Typically, hydronic heating systems use a boiler to heat the water and baseboard convectors, located in each room, to distribute the heat.

A centrally located thermostat controls your desired air temperature. When heat is needed, the boiler heats water that is circulated via pipe to baseboard convectors. The baseboard and surrounding air are warmed as the heated water circulates through the baseboard. The heated air is distributed throughout the room by natural convection.


In larger or multiple level homes, the house is “zoned” with several thermostats that control temperatures in each zone.

Some hydronic systems use piping in the ceiling or floor and are called radiant heating systems because they “radiate” heat to the room. Heated water is circulated through the piping and warms the floor or ceiling.

Radiant heat relies on the heated panel (e.g., floor or ceiling) to heat the surrounding surfaces in rooms. These surfaces then re-radiate the heat, which warms the room’s occupants, and eventually heats the air in the room. Radiant hydronic systems can be zoned by individual thermostats.

Forced air hydronic systems circulate heated water through a fan coil located in the furnace cabinet and distribute heat via fan-forced air through the duct work.



How to operate hydronic heating systems

Like conventional forced air furnaces, hydronic heating systems are controlled by a thermostat. The system heats your home until the desired temperature is sensed by the thermostat and the system shuts off.

Hydronic baseboards also are controlled by a single thermostat. These systems rely on convection around and through the baseboard to distribute heat, therefore, it is essential that the baseboard be kept clean and furniture placement should allow for free air movement. A couch or bed placed in front of the baseboard will prevent the system from heating the room effectively.

Radiant floor or ceiling systems rely on the warmed floor or ceiling to heat the room. As a result, it may take some time to feel an added warmth once you turn the thermostat up. So it is important to remember when operating these systems that turning the thermostat up is not going to heat the room faster, especially if the piping is in a concrete floor. Wait at least 30 minutes after setting the thermostat before readjusting.


How to maintain hydronic systems

Maintenance of hydronic systems depends upon the type of system you have. If you have a forced air system, it is important to change the furnace filters on an annual basis. If the fan coil becomes dirty it should be cleaned according to the manufacturer’s recommended procedures.

Baseboard convectors need routine cleaning and vacuuming to ensure that the convective fins are free from dirt and lint.

Radiant floor and ceiling systems have no need for maintenance except for the routine upkeep of the boiler or water heater.

Boilers and water heaters require routine maintenance as recommended by the manufacturer. Also, it is important to regularly inspect the water pressures in the circulation loops. Most systems are equipped with a pressure gauge that reads the pressure of the water loop. A loss of pressure indicates a loss of fluid in the loop.


Hydronic system options

Forced air hydronic systems can be equipped with air conditioning options. For maximum comfort and efficiency, you may want to consider purchasing programmable multi-stage thermostats. These thermostats allow you to program your system to automatically setback and setup the room temperatures.



Problems with hydronic heating systems typically involve malfunctioning of the boiler or water heater, the circulation pump or the controls. To check the controls, simply turn the thermostat up or down and wait for the corresponding response.

In some cases, there may be time delays of two-to-three minutes before the system changes operation, so be sure to wait at least five minutes before determining you have a control problem.

When determining whether or not your circulation pump is malfunctioning, remember that newer systems operate very quietly and make little, if any, noise while working. If there is no “On” light indicating the machine is working, feel the pump for vibration.

Troubleshooting a malfunctioning boiler or water heater is easily accomplished if the circulation loop is equipped with a thermometer that displays the circulation fluid temperature.

Check the thermostat regularly to see that the boiler or water heater is heating the water while the circulation pump is operating. However, if your circulation loop is not equipped with a thermostat, recognizing a problem is difficult.

If you suspect a problem with your hydronic heating system, call us.

Jim Lavallee Plumbing
Serving Eastern Massachusetts and the Boston area
Phone: Toll-free (888) 884-412



(original article)

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