What Size Boiler Do I Need For My House?

If you are looking for boiler replacement, you likely searched for them on Google. However, your search might have been more confusing than when you started.

What size boiler do I need? How is boiler size measured? What’s a BTU? What’s GPH?

Go to the basement and look at your sticker. It makes sense, but this can be an inaccurate way of measuring your boiler size. This assumes that the existing boiler in the home was sized correctly to begin with.

In most cases, older boilers are oversized and use more fuel than necessary. They may not even last as long as a newer boiler. Oversizing can cause the boiler to "short cycle" a process in which a boiler turns on and off every few minutes in cold weather.

Having an undersized boiler is problematic as well, because the home might not be heated enough on the coldest day of the year. A boiler becomes undersized when it’s incapable of producing enough heat for a home. Compared with undersized boilers, problematic oversized boiler installations are pretty rare.

If you need to install a new boiler, your installing contractor can answer any questions. This article will help you understand how boilers are sized, and why that's so important.

Need help choosing a heating and cooling contractor? Check out our blog post, 8 Tips for Choosing a Heating and Cooling Contractor.

How do BTUs work?

BTUs are the most common way of measuring a heating system. BTU stands for British Thermal Units, and is a measurement of how much heat energy can be created. The other abbreviation, BTUh which stands for British Thermal Units per hour, simply refers to how many BTUs can be created each hour.

To get an idea of the power of a product, look at the BTU rating. For example, if an object has rating of 80,000 BTUs then it will produce about 80 MBH (1 MBH = 1,000 BTUs).

There are many different ways to measure heating capacity. BTUs are the most common way though.

A BTU is the power needed to raise one pound of water by one degree in an hour.

How to calculate boiler size

The size of a boiler can be determined by matching the heat output to the home's needs.

There are no shortcuts for properly sizing a boiler, even experienced contractors cannot size a home by its insulation value. The size of the home doesn't tell you how big the boiler has to be. Other factors like exterior windows and doors also matter, depending on their size and R value of their insulation.

"So how does a contractor take all of these factors into account when sizing a boiler?"

The best way to calculate how much heat you need

There are a few different methods of calculating BTUh. Manual J is the most common way to calculate it. It takes into account how much heat is needed in each room and the type of windows used in those rooms. A program would normally be used to speed up the process.

The contractor starts by measuring the size of the home using square footage. He then also measures the height of the walls and windows, as well as their efficiency.

Before replacing the boiler, take a little time to hire an experienced contractor and go through the house. They will then calculate how much money it would cost to replace the boiler.

Outside design temperature is just a term used for accounting for cold conditions when designing a heating system. For example, in southern Maryland and northern Alaska the same home will require different size boilers.

What size boiler do you need?

Sizing steam boilers requires an understanding of steam and radiation. Too much or too little of either can cause a variety of problems, from noisy heating systems to uncomfortable homes.

To size a boiler, contractors must first determine the square footage of the system to which it will be connected. The process is called an equivalence of direct radiation (EDR). This is done by calculating each radiator's height, length, and width and then doing some math to figure out its volume.

What size boiler do I need?

Say goodbye to rising energy bills with the help of a properly sized boiler. You'll know that you have the right model if it meets your home's needs and has the capacity to meet surface requirements.