How To Restart The Furnace After Running Out Of Propane

Propane is arguably the best fuel for residential heating and even cooking. For one, it’s cheaper than electricity. Additionally, it’s a lot more potent than natural gas.

Although you’ll currently pay about $6.23 for natural gas and $26.99 for the same amount of fuel, propane gives you twice as much heat. So, effectively, it means you need far less propane to keep the home at the same indoor temperatures.

Unfortunately, though, propane comes in cylinders that you must refill. This is one of the main downsides compared to natural gas and even electricity. The latter two are in constant supply. As long as you have a connection and pay your bills on time, you’ll never run out of electricity or natural gas – save for occasional disruptions on the supplier end.

Meanwhile, with propane, the cylinder eventually runs empty after several hours (or days) of use and must be refilled. That’s when problems begin.

On the odd occasion, the propane-powered furnace may fail to light after you’ve refilled the tank – until you restart it. Often, it’s because of air trapped in the gas lines. When this happens, you may have to restart the furnace to discharge air.

Although it’s not a very complex process, restarting the furnace isn’t as easy as pressing a button or flipping a switch. It’s a process that can take several minutes.

What Happens When Furnace Runs Out of Oil?

There’s a common misconception that running out of heating oil can cause furnace damages. That’s not true. Although you should always try to refill the tank before it’s completely depleted, there’s no need to fear even if your well runs dry. 

For one, furnaces come with emergency switches that will turn off the unit when it runs out of oil. The switches are automatic and designed to prevent furnace damage. 

That said, however, running out of heating oil can lead to preventable fuel line clogging. It can also accelerate the clogging of filters within the heater. For this reason, you shouldn’t let the heater sit too long with an empty oil tank. 

Fortunately, you can refill your oil-powered furnace with ease, even without the help of an HVAC pro – unless it refuses to turn on, in which case you’ll need to bleed it. Of course, you need to be reasonably knowledgeable about furnaces to bleed it right. Otherwise, you’ll need to call the pros. 

How Can You Tell that You’re Out of Heating Oil?

If you suspect you may have an empty oil tank but aren’t entirely sure, the following tell-tale signs should be enough evidence. 

The heater suddenly goes off

The oil heater can go off suddenly for many reasons, and an empty oil tank is one of them. This is especially true if you’ve gone several days without refilling the unit.

You can manually check the unit to find out whether the tank is indeed empty. Or, check the LED control panel if it has one. Most oil furnaces display “0” or “E” for Empty when fuel is depleted. 

The oil tank gauge reads “1/4”

If your oil tank has a working gauge, a floating bar will indicate how much oil is left in the tank. We recommend refilling the tank when it reads between ¼ and 1/3 full to avoid running out of fuel. So, if your tank reads below ¼, that’s all evidence you need to conclude that you have a near-empty tank. 

Look inside the fuel tank

Remove the largest cap on the top of the oil tank and, using a flashlight, look inside the tank. If the tank is more than halfway full, then you’re in good stead. However, if you can see right to the bottom of the tank, you need to refill the tank.

The same applies if you can see a pile of residue at the bottom. The residue isn’t heating oil. The residue is very dangerous for your furnace. 

Measure the oil level manually 

Find a yardstick or clean rod long enough to reach the bottom of the tank. A dipstick also works excellently for this purpose. Then, insert it to the bottom of the tank, holding the top end in your hand perpendicular to the oil level.

You can use depth measurement to determine the volume of oil left inside the tank. Depending on the size of the tank, a 10-inch depth might mean about 86 gallons remaining (for a 275-gallon tank) or 81 gallons for a 550-gallon tank. 

Other signs 

Other signs that may also point to an empty or near-empty furnace oil tank include strange noises (resulting from air being pulled into the fuel lines because of lack of oil) and weird smells (resulting from clogged spray nozzles).

The smells usually come from oil residue that doesn’t burn properly. Finally, the heater may also keep resetting to tell you that it’s not getting enough fuel to sustain a healthy flame. 

How to Restart Your Furnace

The following is a step-by-step guide to help you restart your propane heater if it won’t start after refilling the cylinder.

Preliminary Steps

 Before you begin, you need to take care of two things – ensure proper safety and shut off the furnace for further protection.

  • Safety precautions 

Remember that you’re dealing with propane – a highly asphyxiating and explosive gas. When inhaled, the gas displaces oxygen in the lungs, making it difficult or even impossible to breathe at high concentrations. Additionally, the furnace gets extremely hot during operation. Furnaces also connect to electricity.

Thus restarting a furnace puts you in great danger. Ideally, it would help if you considered letting a licensed HVAC professional handle the matter. However, if you feel confident in your DIY skills, proceed with great caution.

  • Shut off the furnace

Here should be a switch directly on your furnace for this. However, if you can’t locate the switch, use the reset button. Whichever method you use, you can verify that the heater is off if the On/OFF LED lights up red. It usually lights green when the furnace is running.

Additionally, disconnect the circuit breaker. This effectively disconnects the furnace from the home’s electric supply to prevent electric shocks during the process. All you need to do here is flip the breaker switch. Most breakers are designed to display an OFF sign on the switch when the breaker is disconnected.

Restarting Furnace After Running Out of Propane – Step-By-Step Process

Now, you’re ready to restart the propane heater. Proceed as follows.

Step 1: Fill the tank

Bleeding the tank without first refilling the tank is zero work. So, begin by purchasing quality heating oil from an authorized supplier and use it to refill your tank. Make sure not to overfill it. Most heaters have a “MAX” level to help you fill it appropriately. 

Step 2: Hit the reset button 

This step will help you determine whether you need to bleed the heater in the first place. If you hit the reset button and the furnace roars back to life on its own, you no longer need to bleed it. However, if it doesn’t restart when you hit the restart button, you most likely need to bleed it to clear the fuel lines of debris and trapped air. 

Step 3: Turn off the heater 

Turn off the heater after it refuses to restart after two attempts. You can shut it off manually by finding the white switch. Alternatively, check if the reset button has automatically turned off the unit. Many modern oil heaters utilize the reset button to automatically start and turn off the heater to make the whole process more convenient for the user. You’ll know that the heater is off if you see a red light on the furnace controls. 

Step 4: Gather the necessary tools

 To bleed an oil heater, you need a couple of things. First, you must have an adjustable wrench or an Allen key to fit the bleeder valve. Feel free to check your manual to determine the best option. Or, you can bring both. Additionally, you need flexible nylon tubing. Ideally, bring a ¼ inch diameter tubing. However, you only need about a foot of tubing. 

Lastly, you need a container to catch the oil waste from your fuel lines. A sizeable coffee can, or a small bucket is more than sufficient. Putting a little sawdust in the container can help prevent the oil from splashing. Don’t forget to wear clothes you won’t mind getting dirty. Also, find an old towel for your hands. 

Step 5: Find the bleeder valve 

To do so, you’ll need to locate the fuel pump. The pump has tubes on it. The bleeder valve is the tubing with a hex nut on it. It’s usually on one extreme of the fuel pump. The nut can be made of steel or rubber. It may also be slightly hidden on some furnaces. 

Once you find the bleed valve, loosen the nut a little bit without unscrewing it altogether. You want to make sure it’s ready when you need it. 

Step 6: Attach the nylon tubing 

Slide the tubing into the bleeder valve, positioning it such that the other end leads to the container you prepared earlier. Alternatively, have a second person direct the other end of the tubing into the container to lessen the chances of splashing. 

Step 7: Turn ON the furnace and loosen the bleed valve

Usually, you’ll only need one turn to release the oil from the lines. Allow it to drain until solid comes out. If nothing comes out, try resetting the furnace a few times. If there’s still nothing, you might have a clog. It’s time to call the pros. 

Step 8: Re-tighten the valve 

Whether you successfully bleed the lines or not, make sure to re-tighten the bleeding valve when you’re done. Also, make sure to remove the nylon tubing and dispose of the oil and debris in your container appropriately. 

What Else Do You Need to Know?

First off, restarting the gas heater can be important when the furnace won’t start after refilling the tank. However, it’s not always necessary. Sometimes all you need to do is try a few times, and the heater will come on. You may only need to restart it if the problem doesn’t resolve itself after many trials.

On the same note, keep in mind that restarting won’t always solve the problem. For example, sometimes, you may restart the furnace after refilling the tank, and it still won’t come on. When this happens, you may need to bleed the heater. Bleeding means clearing up the gas lines of dirty fuel. The process can also help eliminate air trapped in the gas lines.

Do not attempt to bleed propane heaters on your own. The only time you can attempt DIY bleeding is when using an oil heater. And, even then, you must be extremely careful as one mistake is all it takes to put yourself and your family in grave danger.

If you need bleeding, shut off the heating system and contact your HVAC services provider.