How Does A Thermocouple Work On A Patio Heater

How Does A Thermocouple Work On A Patio Heater

Are you wondering, how does a thermocouple work on a patio heater? We have the guide for you to learn all about thermocouples so you can keep your patio heater in good condition.

Thermocouples work based on the thermoelectric effect. This process involves thermal energy being converted to electrical energy. As two different metal wire conductors are connected, a voltage occurs which varies with temperature changes.  As a change in temperature is detected at the measuring point, a voltage is created (variation is electron density of each metal). The voltage is then measured and calculated as temperature.

You invested in a patio heater so you can enjoy your patio comfortably during the evenings. As with all things, the heater can stop working. 

So, it is a good idea to know all about the thermocouple and how to keep your patio heater running. Knowing how a thermocouple works is the first step.

You may not even know what a thermocouple is or what to do with it. Do not worry because we have the guide for you. You will learn all you need to know about the thermocouple, what it does, and how to maintain it. 

The thermocouple is an important component of your patio heater and you don’t want to be left out in the cold.

What Is A Patio Heater Thermocouple

A thermocouple is essentially a safety device for your patio heater. They are found on other devices as well. The thermocouple is designed to keep the pilot lit using a small electric current.

Thermocouples are sensors that measure temperature. They consist of two wires, each made from a different metal. These are welded together to create a junction at one end. 

Any change in temperature that occurs at this junction generates a voltage. The voltage is then calculated as temperature.

Design And Calibration

Thermocouples can be found in several designs including probes, probes with connectors, transition joint thermocouples, infrared thermocouples, and thermocouple wire. 

The range of temperatures is established by the diameter of the wire. Every calibration will have a different temperature range.

They can also be found in different calibrations. The most commonly used thermocouples are called Base Metal thermocouples. These are types J, K, E, T, and N. There are also Noble Metal thermocouple or types C, S, R, and GB.

Thermocouple Time Constant

Time constant is defined as the time needed for a temperature sensor to reach a specific change (63.2% of a step change) in the temperature. To reach 100% of the step change value, five time constants are required. 

The fastest response will be given with an exposed thermocouple junction. Smaller tubes and sheath diameter will also result in faster thermocouple responses. However, the maximum temperature might be lower.

How Does A Thermocouple Work

Thermocouples work based on the thermoelectric effect. This process involves thermal energy being converted to electrical energy. As two conductors are connected (two different metal wires) a voltage occurs which varies with temperature changes.

The junction of the two wires is known as the measuring point. The opposite ends are called connection points, and these are connected to a voltage reader. 

As a change in temperature is detected at the measuring point, a voltage is created (variation is electron density of each metal). The voltage is then measured.

A thermocouple is not like a thermometer. It measures the differential temperature rather than the actual temperature. Because of this, they also require a cold junction compensation. 

This ensures that the ambient temperature at the connection ends do not alter the measuring point.

Where Is The Thermocouple On A Patio Heater

The thermocouple on your patio heater will be located near the igniter. It will shut off the gas in the event the igniter is not working. Should you need a new igniter, these can be found easily on Amazon. 

The thermocouple will also shut off if the electric igniter fails. It looks like a small piece of thin metal tubing or a wire. Typically, it is located near the front of the heater.

How Long Does A Thermocouple Last

Thermocouples can last for several years however, they do not last longer than the heater or furnace they are in. You can get replacement thermocouples from hardware stores as well as Amazon. 

Because they come in different sizes, you may want to check with a professional before you buy, to make sure you get the right replacement.

Patio Heater Thermocouple Not Working

You bought the patio heater to keep you nice and toasty when you are sitting outside. But it is no good if it is not working. Bad weather as well as wear and tear can be the reasons the heater is not working.

A broken thermocouple can also be to blame. It is helpful to know how to check this and to identify if it can be repaired or needs to be replaced.

If your patio heater is broken and you are looking for a new one that will stand up to bad weather, check out my article on the Best Patio Heaters For Wind

How Do You Check If A Thermocouple Is Working

To check your thermocouple, you will need a wrench, screwdriver, lighter or candle, and a multimeter. Multimeters can be found for an affordable price on Amazon.

The thermocouple will be near the igniter part of the heater towards the front. It will be made of a tube, wires and a bracket. The tube is positioned above the bracket and there will be copper wires leading from the tube to the heater.

The first thing to do is an inspection. There are several things to look for that indicate a problem.

  • Discoloration
  • Cracks
  • Pinholes
  • Missing insulation around wires
  • Corrosion of wires
  • Faulty connectors

Using a multimeter, check the thermocouple. Make sure the heater is off and remove the thermocouple. Unscrew the copper lead and connection first and then remove the bracket nuts to do this. 

Make sure the meter is set to ohms and touch the two leads to it. It should read zero. You can then change it back to volts.

Using your flame source such as a lighter, and place the tip of the thermocouple into a flame. As it heats up, attach one lead of the meter to one side of the thermocouple. 

Then attach the other lead to the end of the thermocouple by the igniter. A working thermocouple will produce a reading of 25 to 30 millimeters.

How Do You Know If You Have A Bad Thermocouple

After performing a test with the multimeter, a reading of below 25 millimeters indicates that you need a new thermocouple. You can also tell if the thermocouple is bad if the heater will not ignite. 

If the pilot light is not staying lit, the thermocouple is likely to blame. If the pilot flame is lit but very small, you may only have a small obstruction in the pilot tube.

What Happens If A Thermocouple Fails

The thermocouple is designed to keep the pilot light lit. If the thermocouple is not working the flame will not stay on. It may also produce only a small flame if there is a thermocouple malfunction. Without a pilot light, the gas valve will not work, and neither will your heater.

Because the thermocouple serves as a safety device, you should not use the patio heater if it is not working. You first need to establish if the thermocouple is at fault, and get it repaired or replaced before the heater can be used.

How Much Does It Cost To Fix A Thermocouple

You can get replacement thermocouples from Amazon for less than $15. If you are not experienced or you want to hire a professional to replace it, the price will be higher. Repairs and replacement can cost as much as $150 when done by a professional.

How To Replace Patio Heater Thermocouple

To replace the thermocouple, first remove the covering on the heater to see the igniter. Typically, you will need a screwdriver to do this.

Removing The Old Thermocouple

You will see that everything is connected so that the igniter and thermocouple are held into place. This ignition assembly can be loosened by unscrewing one screw. 

Unscrew the box housing at the back of the thermocouple and slide it back. Loosen the nut that holds the thermocouple in place with a pair of pliers. Then you can pull the wire connectors loose with your hand.

Installing The New Thermocouple

Take the new thermocouple and connect the connectors to the tilt switch. Connect the other end to the gas valve. Use an 8mm wrench to tighten this connection. Run the thermocouple and wires back through the box housing. 

Essentially putting it back in the reverse way as the old thermocouple was removed. Insert it through the hole at the front, reconnect the housing, and tighten the bolt around the new thermocouple.

How To Bypass A Patio Heater Thermocouple

If the thermocouple is not getting any heat, the pilot light for your heater will not stay lit. There are ways to bypass if this need be until you can get the thermocouple replaced.

You can remove the spring valve from inside the thermocouple. First move the tilt switch wire out of the way and using an 8mm wrench, remove the thermocouple from the heater. 

Take a 13 mm socket wrench and pull the valve housing out of the way. If you do not have a socket wrench, you can buy a reliable and cheap socket set from Amazon for all handy projects like this.

Using pliers, remove the valve. You can identify the valve as the part that pushes in and out with the thermocouple. It creates the electricity that allows the electromagnet to open. 

Remove this spring valve using pliers and replace the thermocouple back into place. Now gas can flow directly to the burner as soon as it is turned on.

How To Clean Patio Heater Thermocouple

Regularly cleaning your heater and thermocouple is the best way to ensure it lasts longer. Keeping it clean will help it to light and stay that way. 

Winds can blow debris into the heater and rainwater can wash out the fire. When possible keep the patio heater under a canopy or out of the elements when not in use.

Cleaning The Insides

To clean inside the heater, first turn off the gas. Clean the pilot by removing dirt, oil build up and spider webs. Use a damp rag to wrap around the inside and a dry towel when done. 

The thermocouple can also collect dirt and bugs. Remove the flame screen from the heater and remove the thermocouple by unscrewing the bolts.

Use a hose to rinse inside the tube. After it air dries, reconnect the thermocouple. This will now let gas travel easier to the flame so your patio heater will stay lit. 

Reconnect your gas and tighten the connection between the pilot and gas valve if needed.

Check For Gas Leaks

You can also take this time to check for a gas leak. Using soapy water on the heater hose, you will see bubbles where any leaks are present. Should you find any leaks, contact a professional for repairs. Working directly with gas is tricky and dangerous.

Stay Protected

Invest in a patio heater cover from Amazon. This will protect the heater front he elements when not in use. You can also store the heater in a garage or shed during bad weather. 

The more protective you are of the patio heater, the less likely the thermocouple will falter. They should last for several years, so if you are replacing one much sooner than that, your maintenance schedule could be to blame.

Helpful Tips For How Does A Thermocouple Work On A Patio Heater

The thermocouple plays a big role for a small device. Without it, the pilot light on your patio heater will not light. This means no heat for you. 

Rather than face the cold, you can clean, maintain, and even replace your thermocouple with ease. A few helpful tips to remember before you start:

  • Always use a multimeter to test the thermocouple first
  • Check for gas leaks regularly
  • Make sure the gas if off before looking at the thermocouple
  • Contact a professional if needed

Final Thoughts

The thermocouple is probably not anything you have given much thought to. Don’t feel bad if you did not even know what it was. 

Without the thermocouple, your patio heater will not do as intended. It therefore is important to understand this device to stay toasty when relaxing outdoors.

So, how does a thermocouple work on a patio heater? Our guide helps you maintain and understand the thermocouple, so you can take better care of your patio heater. 

This small device makes a big difference, so follow our guide and don’t get caught in the cold.

Drew Thomas

My name is Drew Thomas and I’m the creator of Fun In the Yard, your one stop site for all your outdoor games, sports, party activities, outdoor gear, and lawn & gardening tips.

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