Should I Turn Off My Furnace During The Summer?

It’s a question that many homeowners ask once the summer gets into full gear: can’t I shut down my oil furnace to save energy?

The answer depends on several factors, including what type of oil furnace you have, how you’re using it, and what your personal preferences are (of course, it’s important to first determine if you even have a furnace: if you have radiators, radiant floor heating, or baseboards, you don’t – you have a boiler).

Why would a furnace run during the summer?

There are several reasons why a furnace would continue to run year-round…here are three of the most likely candidates.

• It could be old. Older furnaces (15+ years old) are typically lit by a pilot light, which runs 24/7/365; if your pilot light goes out, your furnace won’t work. Pilot lights were used for convenience: they enabled the furnace to fire automatically, without someone having to light it by hand each time the house needed heat.

  The problem with pilot light designs is that they are inefficient. The Annual Fuel Utilization Efficiency (AFUE) ratings of these older furnaces range from 56 to 70 percent –  which means a little more than half of the energy from the oil becomes heat for your home (by contrast, modern oil furnaces – which use an electronic ignition – can reach efficiency ratings into the mid-90s).

• It could be heating your water. Modern indirect water heaters and older tankless coil systems are fairly common today; these options use the power of your furnace (or boiler) to heat the water in your home. This streamlined approach saves energy because your existing central heating system doubles as a water heater.

  The process works great during the months where you have your heating system on anyway (you’re basically getting your hot water for free – a big deal considering water heating can account for almost 20 percent of your energy bill), but it requires you to keep your boiler or furnace running year-round (although an indirect water heater runs less frequently – and much more efficiently – than a tankless coil system). Read more about these water heater types here.

• It could be assisting your cooling system. Some HVAC systems are set up so the central air conditioning system works with the furnace to keep the house cool (if you use window units, your furnace is not cooling your home).

  In central air conditioning systems, your furnace powers an outdoor compressor and AC evaporator coil. The compressor keeps the evaporator coil cool with refrigerant to remove heat and humidity from your home. Your furnace’s blower then spreads the cold air from the coil throughout your ductwork and into your living space.

As you can see, understanding why your furnace is burning fuel is the key to determining if it’s possible to turn it off over the summer. But is it recommended? Let’s take a look.

Turning off your pilot light: risks and benefits

If you have a furnace with a pilot light, it is possible to turn it off for the summer: it can save you a few dollars and make your home a little quieter due to reduced blower noise. But it’s not without some risks.

For one thing, furnaces are prone to corrosion from water and soot when they’re shut off during the summer, which can speed corrosion. Inactive furnaces are also prone to attract insect visitors to your fuel tank and fuel and vent pipes; these critters and the debris they create can slow the flow of fuel to your furnace when you turn it on in the fall.

Cleaning your furnace before you turn it off can help prevent corrosion, while topping off your tank can deter insects from moving in and creating debris.

Turning off your furnace

Turning your furnace off for the summer is a straightforward process, which we have outlined below. However, we strongly recommend that you review your furnace’s owner’s manual before shutting down your furnace, since your equipment’s shut down procedure may differ.

For systems with a pilot light

1. Lower the thermostat to its lowest setting.
2. Wait for the furnace to stop its heating cycle.
3. Flip the furnace power switch to “Off.”
4. Twist the pilot light shut-off valve clockwise to cut off its oil supply.
5. Turn the fuel tank’s main shut-off valve clockwise to turn it off.

For systems with no pilot light

1. Lower the thermostat to its lowest setting.
2. Wait for the furnace to stop its heating cycle.
3. Turn the furnace’s power switch to “Off.”
4. Twist the oil tank’s fuel shutoff valve clockwise to shut it off.

So, you see, the answer is not a simple, straightforward one. Give us a call and we can have someone take a look and give you the best answer. If you’ve already decided to turn off your furnace, consider scheduling an oil burner cleaning and a heating oil delivery in RI from the pros at Vaughn Oil to keep your heating system in great shape and ready for the fall!