Potential Troubles of a Wood/Oil Furnace Combination

With the escalating prices of home heating in recent years, many people have begun to make use of a combination wood and oil furnace. This type of furnace gives the homeowner flexibility in what they heat their home with during the cold winter months. While this is a great way to keep some heating costs down, there are some potential problems associated with a combination wood and oil furnace. Here are a few of the problems that you can watch out for for effective use of your wood/oil furnace.

Chimney Requirements

For anyone who is looking into purchasing, or installing, a combination wood and oil burning furnace will want to pay very close attention to the chimney requirements. Since you are burning 2 different types of combustibles they have their own flue, draft, and cleaning requirements. The technical specs on the type of furnace you buy will determine the specific needs. However, most of the time there are different flues for both of the heating services to work.

Space Requirements

After making sure that the chimney is going to be adequate for your furnace, the next most important trouble spot to take a look at is the space where the furnace will go. The oil burning side of the furnace is not going to require much space. Many times they can be closed in very tight quarters. Wood stoves, however, much have plenty of space as they can rise to extreme temperatures. Installing a combination furnace will require at least 3 to 6 feet of clearance around the furnace to protect from fire.

Cleaning Requirements

An oil burning furnace will require an annual cleaning to ensure that is runs efficiently and without any problems. The wood burning furnace must be cleaned every day. As wood is burned there are two things that accumulate within the burn chamber. First, you will have the ash. This must be removed to keep the air circulation at its most efficient. The second particle is creosote. This is not as much of a problem if you are burning process materials such as wood pellets. Creosote can build up very quickly, especially when the weather is very cold and then turns warm. This excess build up will cause smoke to go throughout the home instead of out the chimney.


The thermostat is the piece of hardware that runs the furnace with a temperature that you set. The thermostat is found with any oil burning furnace. Some wood stoves can also be operated via a thermostat in a central area of the home. With a combination oil and wood burning furnace you are going to need to rely on 2 different thermostat switches.

Air Flow

When you burn wood you must have an adequate air flow into the burn chamber so that the wood will burn at the right speed. If you mostly use the oil furnace and then switch to using wood, many homeowners forget to check their air damper on the chimney. This will cause the smoke to be blown back into the home, or the wood to burn inefficiently.