What Size Boiler Do I Need For A 2000 Sq Ft House?

Boilers, BTU’s, and Bucks

Boilers in the Basement – A New Paradigm

The modern boiler in the basement is no longer the hulking cast-iron behemoth of the past. Today’s boilers are smaller and much more efficient at their job. Technology has transformed hydronic heating into a must more cost-effective means of heating homes. In many areas of the country, hydronic heating is seeing a resurgence among new home builders.

Understanding BTUs – Why Are We Using British Measurements?

First, let’s get the science out of the way. A BUT is a simple measurement. One BTU is a measurement of the energy required to raise one pound of water temperature by one degree. Yes. That sounds simple enough.

The term, British Thermal Unit, has become the standard for rating heat transfer around the world. It has nothing to do with the British other than where and who developed the formula.

It’s All About What You Get from the Boiler

But how does that translate to heating my home and boiler size? What does it mean when a boiler label says the boiler produces 80,000 BTUs? In most instances, the ratings on your boiler label are really BTU/h or British Thermal Unit per hour.

BTU/h is a rating of how much heat is available from the water circulated through your home for heating. This rating is useful for calculating how large a boiler to purchase to heat a given space adequately.

Figuring in the Bucks – The Costs go Beyond the Purchase

Before You Shop, Do Your Home Work

What an HVAC Professional will Consider

During a professional assessment, an HVAC technician will look at your home from top to bottom and check several factors that can affect your heating requirements.

Your Location and Climate

Different areas have different heating needs based on the climate and the location. Northern locations where winters are long and the cold more intense require higher BUT ratings than homes in the semi-desert southwest.

Sun Exposure

Do evergreen trees heavily shade your house. If you live where winters can get intense, the shade of trees can increase your heating requirements. How your house is situated and where the windows face is important in figuring heat gain in the winter from sunlight on southern exposures.

Insulation Factors

How well is your house insulated? Calculating how well your home insulation performs is critical in determining the heat loss that you suffer. This heat loss calculation also considers the weather tightness of your doors and windows.

The Number and Location of Windows and Doors

Windows and doors add to the BTU load required to heat a home. If your home has larger windows and doors, you can expect the BTU requirement to be greater. The need for additional BUTs is especially true if your home has large glass doors serving patios or other outdoor areas.

Ceiling Heights and Special Areas

Homes with higher ceilings or areas where there are lofts or other extended height areas require extra BTUs to heat these larger spaces. A professional survey of your home will take these spaces into consideration

Occupant Load

How many people normally occupy the home is a large factor. If your boiler provides domestic hot water and space heating, the boiler’s BTU rating must reflect this extra load.

What Your HVAC Professional Will Provide

After the survey, your HVAC professional will present you with a comprehensive assessment of your heating needs. The HVAC technician will also make recommendations about the size, style, and features of the boilers that may best fit your needs.

What is AFUE? And Why is it Important?

AFUE is an acronym for Annual Fuel Utilization Efficiency. This number is a rating that shows how efficient your boiler converts fuel into heating energy. The larger the number, the more efficient the boiler.

For example, a boiler with an AFUE of 85 typically converts 85 percent of the available energy produces by burning fuel into useable heating energy. The other 15 percent of the energy is lost up the flue in waste gases.

What AFUE Should I Chose?

The best option is to choose the boiler with the highest AFUE you can find in most cases. Having a boiler with the highest AFUE means that you are capturing as much heat from the fuel as possible. More heat from the fuel translates into lower overall operating costs. You burn less fuel for more heat.

A Note About Fuels

Different fuels have different BUT ratings and yield different AFUE ratings. The primary sources of fuel for boiler operations are

Fuel Oil

Fuel oil is attractive because it produces more heat per BTU than any other fuel. However, oil-fired boilers require an on-site fuel tank, regular fuel delivers, and typically require more maintenance than other types of boilers.

Natural Gas

Natural gas is probably the most widely used fuel for firing boilers. Natural gas boilers are highly efficient and fuel costs are typically low. However, not every place has natural gas pipelines. Natural gas boilers are quieter and require less maintenance. Natural gas is less efficient in producing BTUs than fuel oil.

Propane

Propane is an excellent substitute for natural gas. Like fuel oil, heating with propane requires an on-site tank and extra plumbing. Your boiler may need modification to burn propane, but most plumbers or propane providers can make these adjustments.

Electricity

Electricity rates vary widely across the country. If you live in an area with cheap and abundant electricity, an electrically heated boiler may be the most economical option. A good electric boiler may have an AFUE rating approaching 100. Almost all the electrical energy becomes heat for your home.

Making the Decision – Good Information is the Key

Don’t depend on basic estimations when choosing a boiler for heating your home. Making a sound decision requires good data and proper techniques. Before you purchase a boiler, consult an HVAC professional who can do a proper survey of your home to determine your precise needs. The extra effort will pay off in more efficient operation, lower costs, and a longer life for your boiler.