Hot Water Boilers | Boiler Repair | Boiler Service Near Me



How a Hot Water Boiler Operates

As a home’s room temperature drops below a set point on the thermostat, the thermostat control sends a signal to turn on the boiler system, which starts the following process: Zone valves are opened where applicable, and the circulating pump begins to pump heated water from the boiler to standing radiators, to baseboard radiators, and, in some cases, to a hot water coil located in ducting.

If the water temperature inside the boiler is below a set point on the aquastat control, the control will turn on the burner, which will heat up the boiler water until it reaches the high limit of 180 to 200 degrees (F). The circulator will continue to push the heated water out of the boiler forcing cooler water to return to the boiler to be re-heated. You can observe the water temperature and pressure on a gauge located on the front of the boiler. Temperature should not exceed 200 degrees (F), nor should the pressure be more than 30 pounds per square inch (psi). Following these best practices will help you avoid the need for boiler repair.

As water is pushed out of the boiler, it passes through an air scoop, air separator, or air purge, which removes the air that is suspended in the hot water. This helps eliminate noise in the system operation and stop air-bound radiation that can impede proper heating. An automatic water feeder will add water as needed to keep the system full, and the expansion tank will take any excess water that has expanded during the heating process. A relief valve is also present to relieve excess pressure in case of overheating or having too much water, to help avoid the frequent need for boiler repair.Heated water passing through a standing or baseboard radiator transfers heat to the surrounding air via convection and heat radiation. The room thermostat will sense the temperature, and when it achieves the set point, will shut down the circulator. The burner will continue to heat the water in the boiler to keep it within the range set by a limit control.

A qualified ServiceMark technician should be contacted for boiler repair if any of the following occurs:

  • Noisy or smoky burner operation
  • Excessive air noises
  • Water dripping at relief valve
  • Water dripping at piping connections
  • Smell of heating oil or natural gas

Your ServiceMark Heating, Cooling & Plumbing team is standing by to remedy and repair any of these problems.

To help prevent the need for boiler repair in the first place, our trained technicians can perform an annual heating system service that will:

  • Increase system efficiency and reduce monthly energy costs
  • Ensure safe operation and prolong equipment life
  • Reduce inconvenient and costly service calls


Please call ServiceMark at 1-800-474-5200 for guidance on the best ways to save energy dollars, season after season.

With physical locations in Exton, King of Prussia and Wilmington, we are able to provide boiler repair and other services to Delaware, Chester, Montgomery and Bucks Counties in Pennsylvania; New Castle, Kent and Sussex Counties in Delaware and Cecil County in Maryland.

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