Replacing A Patio Heater Thermocouple

Patio heaters are fitted with a thermocouple, this device controls the flow of gas and ensures it’s working normally. A thermocouple that has failed will switch the burner off, you’ll notice this when the pilot lights but goes off when turned up. Changing the thermocouple fixed 90% of the firing problems, if you ever wondered how to change one just read on.

You’ll need a 8mm spanner, pliers and Philips type screwdriver.
Make sure the lpg gas cylinder is NOT connected, and heater has NOT been fired up for at least 60 minutes.

These instructions are for branded BFX750 gas patio heaters, generic or unbranded patio heaters can vary. Some additional tips are included for generic patio heaters.

The patio heater thermocouple cannot be safely accessed in situ, you’ll need to take the burner off the pole. To do this remove the wing nuts holding the reflector and lift the reflector off. Next disconnect the gas regulator, either unclip or cut the LPG hose close to the fitting. Older generic patio heaters may have a steel gas pipe that runs inside the pole, if so you’ll need to replace the small washer seal inside when refitting. Remember to store all the parts for reassembling later.
Most patio heaters will have 4 stainless steel bolts securing the burner to the pole, see picture below. Unscrew and take care holding onto the burner to ensure it doesn’t fall off.

patio heater pole fixing screws

Patio Heater Pole Fixing Screws

With the burner off the pole place it upside down in on a table or a work area. First check for any cracks or wear to the LPG hose, replace the hose if there are any signs of damage. You will notice some small bits of metal inside the flame screen, this is normal and will not harm the burner. Branded BFX750 patio heaters have a stainless steel casing, generic patio heaters are often manufactured in tin or chrome so the casing on a generic heater could be pitted. If you have a lot of rust use a wire brush to clean and remove as much as you can. If the rust is very bad (tin/chrome burner have a life of 2 years or less near coastal areas) then it might not be worth salvaging.

patio heater burner repair

Patio Heater Burner Repair

With the Philips type screwdriver unscrew the 4 stainless steel screws holding the flame emitter screen in place. Normally they will unscrew with ease but tin/chrome burners may struggle, if so try using a blow torch to loosen the screws. Store with other parts.

patio heater flame emitter screen

Patio Heater Flame Emitter Screen

The easiest way to access the thermocouple is to take the mesh off in one go, unscrew the stainless steel screw at the top of the mesh panel – see picture below. Lift the mesh off by squeezing; it should come away in one cylinder. You now have full access to the patio heater gas control valve and tilt swtich if fitted. Store with other parts for reassembling later.

burner mesh screws

Remove Mesh Screws

Good quality patio heaters will have a tilt switch fitted as standard, this is a small black box with 2 leads. The tilt switch turns the gas off when the patio heater is tilted or moved. Take the pliers and pull off the 2 spade connectors attached to the tilt switch. On some generic patio heaters these can be soldered on in which case you’ll need a soldering iron to remove.

remove patio heater tilt switch leads

Remove Tilt Switch Leads

You’ll see the thermocouple at the back of the patio heater gas control valve. Using the 8mm spanner unbolt the small brass connector to loosen and remove the thermocouple. This should unscrew easily, just pull away from the back of the gas valve – see below.

pull thermocouple away from gas valve

Rear Of Gas Valve

Last job is to flip the burner upright facing towards you. You will see the tip of the thermocouple, on branded BFX750 patio heaters the thermocouple is held in place using a clip. Since a thermocouple is a consumable item that will require changing every few years this system is designed for ease of use. Generic patio heaters may use a steel nut, these tend to corrode and make it difficult to remove. Just unclip using the pliers and the thermocouple is now ready to remove – see below.

unclip patio heater thermocouple

Unclip The Patio Heater Thermocouple

Pull the old thermocouple out and you are ready to refit a new patio heater thermocouple. Follow the instructions in reverse order and when done ensure a leakage test is conducted before firing up the patio heater. For instructions on how to leak test and solutions to other patio heater problems please read Patio Heater Guide To Problem Solving.

replace patio heater thermocouple

Replacing A Patio Heater Thermocouple