Heater Element Problems

The heater elements are white ceramic plates with two white wires connected that are attached to each ceramic heater plate. They are attached to the ceramic plate with a metal clip which holds them in place. There is also some white thermal paste between the element and the plate to ensure good heat transfer. Often this paste can dry out and go hard which people often think is some form of glue (which it is not!). For more details about the thermal paste please read this FAQ page.

We've split this page into two sections and it is important you read the correct section based on the model of GHD irons you are trying to fix:

All heater element resistances discussed on this website are nominal values and it is normal for them to vary plus or minus 10ohms either way. Heater elements will either work correctly or be open circuit. I've never seen an element with an incorrect resistance - they do not age or vary resistance significantly with age.

Mk3 Heater Elements

The Mk3 irons use the resistance of the heaters to control the temperature - as they get hot the resistance changes and this change is measured by the microcontroller.

The red light that the user sees is illuminated whenever the heaters are switch on. Therefore when the irons are first switched on the red light is on all the time as the heaters are on at full power. As the irons approach the operating temperature the heater power is turned down (by switching them off for short periods of time) which means the light starts flashing. Once they are at the operating temperature then the flashing slows right down.

If one or both of the heater elements break it will be detected by the microcontroller and heaters do not get energised. This means the light does not come on and the irons will look to be completely dead. Sometimes you may be able to see a very faint glow of the red light (try the irons in a dark room) if just one element is broken.

Mk3 Heater Element Failures

There are two common types of heater element failure seen in the Mk3 GHDs:

1) Heater elements cracking - This can either be a hair line crack that you can't see or a big crack which means the element is in two pieces. This can happen because the irons are dropped and the impact has caused the element to shatter, the element has overheated and broken or because an intermittent cable connection has generated a power surge which has caused a localised hotspot and a crack to occur.

2) Wires coming detached - This mostly happens on the older GHD3 or SS model (which have white glue over the heater wires rather than red glue). The spot welding fails and the wires come off. Initially this will manifest itself as the LED only coming on when the GHD's are closed. Gradually they will work less and less until the light doesn't come on at all.

Testing Mk3 Heater Elements

If you are testing GHD3's for the heater wires coming off, just try gently pulling on the wires between the heaters and the PCB. Any bad wires will just come off in your hand.

In all GHDs the heaters are in parallel when connected to the PCB. This means that if both heaters are working, then you will measure half the heater resistance when they are connected to the PCB. If you are unsure, just disconnect the heaters and then measure them on their own. If you need a soldering iron to disconnect the heaters, then you've got fake GHDs.

Mk3 GHDs have 160 ohm heaters so you'll measure about 80 ohms when they are both connected to the PCB and 160 ohms when they are disconnected.

Repairing Mk3 Heater Elements

Obviously if an element has cracked then it cannot be repaired. A number of people have tried to repair heaters with detached wires, however I've not heard of anyone who has successfully made it reliable again.

Soldering the wires can work for a while, however at 180 deg C the solder will soften and the connections will soon fail again.

Therefore I recommend replacing the heater element with a new one (see the next section for details).

Replacing Mk3 Heater Elements

Instructions for replacing a heater in a pair of 3.1b's are here. These instructions are also basically correct for GHD 3's as well. When fitting heater elements you must apply a small amount of thermal paste. For more info about this paste, see the thermal paste page

The heaters in Mk3 GHDs have a different resistance to the heaters in Mk4 GHDs. Therefore make sure you get the right ones for your GHD version.

We stock the following two types of heater suitable for Mk3 GHDs:

The GHD MS uses a narrower element. This is available here:

After replacing a heater element in a Mk3 pair of GHDs you may need to recalibrate the irons for the new heater resistance. This can be done using the VR1 calibration resistor however you should do it with GREAT CARE! For more information about doing this please read the VR1 page.

Mk4 and Mk5 Heater Elements

The Mk4/Mk5 irons use a thermistor to measure the temperature of the heater on the non switch side arm. For more details about the thermistor and how to replace it please read the thermistor page.

The red light that the user sees is software controlled and does not tell you anything about the power going to the heater.

If a heater breaks you will see the following symptoms:

Mk4/Mk5 Heater Element Failures

The only failure mode we've seen in the mk4/Mk5s is the heater elements cracking - This can either be a hair line crack that you can't see or a big crack which means the element is in two pieces. This can happen because the irons are dropped and the impact has caused the element to shatter, the element has overheated and broken or because an intermittent cable connection has generated a power surge which has caused a localised hotspot and a crack to occur.

As the irons are now older, we are seeing broken wires at the element end or the PCB end where the wires are screwed to the PCB

Mk4/Mk5 Heaters Operating at the Wrong Temperature

The only problem we have seen that results in the plates operating at the wrong temperature is if there is not enough thermal paste under the heater with thermistor. If a heater is broken then it will be open circuit - if it gives a resistance then it is working normally. If you are having problems with the irons working at the wrong temperature then have a look at the thermistor page.

Testing Mk4/Mk5 Heater Elements

In all GHDs the heaters are in parallel when connected to the PCB. This means that if both heaters are working, then you will measure half the heater resistance when they are connected to the PCB. If you are unsure, just disconnect the heaters and then measure them on their own. If you need a soldering iron to disconnect the heaters, then you've got fake GHDs.

Mk4/Mk5 GHDs have 70 ohm heaters so you'll measure about 35 ohms when they are both connected to the PCB and 70 ohms when they are disconnected.

Replacing Mk4/Mk5 Heater Elements

We have some videos on dismantling the heater assemblies on Mk4 and Mk5 irons:

Thermistor Side (Non Switch Side)

Thermal Fuse Side (Switch Side)

When fitting heater elements you must apply a small amount of thermal paste evenly and thinly over the element. For more info about this paste, see the thermal paste page

The heaters in Mk4/Mk5 GHDs have a different resistance to the heaters in Mk3 GHDs. Therefore make sure you get the right ones for your GHD version. The resistance is different so that the Mk4/Mk5 irons can also work in the US at 110V.

We stock the following types of heater suitable for the standard 1" Mk4/Mk5 GHDs:

The GHD MS4.0 uses a narrower element. This is available here:

The GHD SS4.0 model uses a wider heater.

After replacing a heater element in a Mk4 pair of GHDs there is no need to perform any calibration as the temperature control is done via the thermistor. The only reason they would operate at an incorrect temperature is if the wrong thermistor has been fitted or the element has not been fitted to the ceramic plate correctly. See the thermistor page for more details.

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