Oil vs. gas heat – what's the difference?

What's better – oil or gas heating? While there's no way to define which is “better,” there are a range of factors to consider when making the decision between the two big dogs of the heating world.

Natural gas installation (Image: Gordine N / Shutterstock.com)

How to find out which fuel is best for your home

When deciding whether gas or oil heating is the best choice for you, there are several factors to consider. Among other things, you should take into consideration supply and usage factors, the equipment needed to heat with each, and the overall operation and efficiency of these fuels and systems.

Supply and usage

Natural gas is much more commonly used than oil for home heating in North America. However, there are some areas of the country where natural gas infrastructure is lacking, and oil heating is more popular.

In terms of supply, natural gas is more convenient, with a pipeline connecting the fuel supply directly into your home from your area's natural gas utility company. This means that you pay for what you use at the current rate, and there is no reason to worry about your fuel supply running out, unlike oil which must be purchased up front and delivered by truck to your home's oil tank.

Although it must be paid for on delivery, oil prices are a bit more flexible than gas, as you can shop around to find a better price from different suppliers. Some oil companies will also give you the opportunity to lock in your price per gallon at the beginning of the year. If the price is low during contract time, go for it! On the other hand, if the price is high at the time you sign-on, hold off and wait for prices to go down again. If you sign the contract during a time where oil prices are high, you'll be stuck at that rate for the year, eliminating the opportunity to pay a lower cost once prices drop again.

Equipment and service

With an oil heating system, the boiler will almost always be larger than a natural gas boiler for the same sized home  – especially when compared to modern wall-mounted gas condensing boilers.

An oil boiler replacement should also include a new liner for your chimney to protect the structure from damaging exhaust and moisture, where with a gas boiler, the chimney can be bypassed for direct venting from the boiler to the outside. Speaking of venting, an oil boiler also requires a bit more space around the boiler itself to pull fresh air into the system. In a gas heating system, that fresh air normally comes directly into the boiler from outside. If stored in an unfinished basement, these differences may not be noticeable, but if kept in living spaces, you might notice some cold air moving around the space near your oil boiler; this is due to the vent intake moving air inside the home. Typically built from cast iron, an oil boiler also requires a heavy metal oil tank as noted above. These tanks can be installed in the basement or buried near your home, but monitoring is in order, as tanks can corrode and leak over time.

While both oil and gas boilers should be serviced annually, there may be a difference in the associated price tags. Because of the way the fuel burns, oil boilers will always have soot formation, which must be cleaned and removed regularly to avoid any reduction in efficiency. Oil boilers will also have an oil filter, which must be changed or cleaned regularly. Gas boilers on the other hand still require service, however there is much less cleaning required due to the size of the boiler and the way the fuel burns.

Operation and efficiency

Natural gas and oil are very different types of fuel, even down to the way they are measured. Gas is measured in Therms (or cubic meters), while oil is measured in gallons (or liters).

Unit for unit, oil is a more energy-dense fuel source than natural gas, with about 40% more energy per unit. However, when installed correctly, a gas condensing boiler can be more efficient than an oil boiler at approximately 95% vs. 87% AFUE efficiency respectively. Per unit of fuel, a gas condensing boiler can provide better heat output.

While oil boilers heat water to a certain high temperature, gas boilers are much more flexible in their heating settings. A condensing boiler, when properly installed and programmed, can heat water to a significantly lower temperature, reducing the fuel required to properly heat a home. On top of that, a condensing gas boiler is designed to condense leftover heat in the exhaust and return it to the boiler, making the system even more efficient.

All in all, oil and gas heating are two very different ways to create the warm and cozy home you're after. Their differences may attract you to one choice or another, but it's always in your best interest to find a trusted heating contractor to guide you into making the decision that is right for you.

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