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What Is the Difference Between a Furnace and a Boiler?

Date: August 23, 2021

A heating system can be quite intimidating, particularly for the new homeowner. Do I have a furnace or boiler? What is the difference between a boiler and a furnace? Do I have steam heat or forced hot water heat? Is there anything I need to do to maintain my heating system? Do I have oil heat or gas heat? These are just some of the questions that any new home buyer might ask.

The following is a quick overview of different types of heating equipment for the first-time homebuyer. Let’s begin with the most basic question.

Oil or Gas Heat?

If you live in the Northeast there is almost a 50/50 chance of having one or the other. Look in your basement. Do you see a large storage tank with two pipes coming from the top of it? Do the pipes appear to go through the foundation or sill of the house to the outside? If you answered “yes”, you likely heat your home with oil.

Below is an example of a standard steel 275-gallon oil storage tank. Notice the two black iron pipes coming from the top of the oil tank. The pipe on the left connects directly to the oil tank and is called the fill pipe. The other pipe is called the vent pipe. It allows air to escape from the oil tank while it is being filled so the tank does not become over-pressurized. The blue-colored device that the vent pipe connects to is called the vent alarm. The vent alarm pictured happens to include a tank gauge located opposite the connecting black iron pipe.

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Does a Furnace or Boiler Heat My House?

A boiler is a heating plant that contains water. The burner provides a flame that heats the water to a high temperature so it can be sent to radiators, baseboard,s or a heating coil to provide warmth. There are two types of boilers. Forced hot water boilers heat water to between 170 degrees and 200 degrees and provide the homeowner with instant heat through a loop. In the below picture the boiler is the large two-toned blue-colored appliance while the oil burner is the small toaster-sized box connected to the bottom of the boiler. Notice the green-colored circulator pumps in the picture below. There are six circulator pumps. Each corresponds to a thermostat in the home and pumps hot water away from the boiler when the corresponding thermostat calls for heat.

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Steam boilers create steam as a heat source. Steam is supplied from the boiler to radiators as a vapor then cools and returns back to the boiler as a liquid. Notice the clear gauge glass on the front of the boiler. All steam boilers have this feature as it lets the homeowner know how much water is in the boiler. It is important that the water level in the steam boiler does not drop below 1/2 in the gauge glass. For safety purposes, if the water level approaches 1/4 the oil burner will not fire. Consequently, the boiler will not provide heat.

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A furnace supplies a home with “warm air” heat. Unlike a boiler, it does not contain any water. Rather, it brings unheated or cool air to it for warming using a blower and return ductwork. The cool air passes across a heat exchanger where it is warmed. The now warm air is distributed to the living area via supply ductwork. One of the simplest ways to confirm that your home is heated with warm air is to look for registers in the floors and/or ceilings of your living space. Supply registers, which bring or supply warm air to the living space, are typically located underneath windows, or in ceilings near outside walls while return grilles are typically located closer to the interior of the home.

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A reputable oil heat dealer should visit your home as part of the “signing on” process with a new customer. During the visit, he or she should have the knowledge and experience to thoroughly introduce you to your heating system, take you through any tasks that you may need to regularly perform to keep your system running well, and of course answer your questions.

Cubby Oil not only has the best supply of quality, high-efficiency furnaces and boilers, we have the best staff of service technicians in greater Boston! Contact us to get started on upgrading your home’s heating system.

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