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Choosing the Best Boiler for your Home Heating System

If you’ve noticed signs that your boiler system is failing, you may need to replace it with a new one. But what is the best boiler system for your home? The home comfort specialists at Main Stream Mechanical discuss key considerations on residential boilers—just in time for the heating season.

Breaking Down the Boiler Basics

Before choosing a new boiler system for your home, it pays to understand what to look for in order to get a more efficient unit. All boilers are either condensing or non-condensing.

  • Condensing boilers use the energy (or waste heat) in the water vapor to preheat the water or air, recovering energy and increasing the heater’s efficiency to 95%. To achieve this, the burner and heat exchanger materials must be resistant to corrosion, and the operating temperature of the boiler must be lower.

  • Non-condensing boilers keep heating temperatures high to prevent water vapor in the flue gas from condensing. Operating a boiler to prevent condensate means that precious heat is lost to the atmosphere as the water vapor is released. This limits efficiencies to the 70-80% range.

Boilers are also divided into two additional categories: sealed-combustion or non-sealed combustion.

  • Sealed combustion boilers use only outside air for the fuel-burning process. A pipe brings outside air directly into the burner, and another pipe exhausts the flue gases directly to the outdoors. This process is sealed and isolated from the indoor air of your home.

  • Non-sealed combustion expels heated air up through the chimney and outside, wasting energy. This type of boiler could also allow hazardous combustion gases into your home.

Buying a New Boiler

There are three considerations to help you narrow down your boiler choices.


Because sizing is critical, it is best to have a professional compute the sizing for you. A unit that is oversized can cause short-cycling, where the system cycles on and off too fast, leaving your home too cold. An undersized boiler will have to work too hard to heat your home, causing a rise in heating bills and damaging your equipment.


Choosing the correct venting option depends on your existing boiler and your home’s construction. Depending on the method used to vent combustion gases will determine your boiler’s location. Residential boilers that vent directly through the chimney can be located in smaller, confined areas. If the boiler is vented by forcing air through a venting system, it will need to be located in an open area that allows it to gather air to use.


The Federal Trade Commission requires that new boilers display their Annual Fuel Utilization Efficiency (AFUE), the measure of how efficiently your boiler utilizes its fuel. The higher the AFUE, the more efficient the system, and the more money you save on utilities. Ratings are categorized as follows:

  • Minimum (Low) Efficiency Standard Boilers have 78% AFUE

  • Mid-Efficiency (Standard) Boilers have 80-83% AFUE

  • High Efficiency boilers have a 90-98% AFUE.

High Efficiency Boilers

A high-efficiency boiler is designed to trap any escaping heat and direct it back into heating the home. The outcome? No wasted fuel and no pollution. While high-efficiency boilers have a higher upfront cost and more stringent installation requirements, they can offer operating cost savings of up to 30% and a reduced impact on the environment.

Boiler Installation, Maintenance, and Repair in NH and MA

Advances in technology have created highly efficient boilers that can save you on energy costs. If you have questions about a new heating system, contact our home comfort specialists. We’ll explain the options, make recommendations, and install your system before the cold weather sets in. We service many locations across Massachusetts and Southern New Hampshire including Haverhill, Amesbury, Newburyport, Rowley, Topsfield, and Boxford.


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