Ideal Boiler L7 Fault Code
The Ideal fault code L7 NTC Thermistor issue Q & A or require an engineer for an emergency boiler repair.
The Ideal Boiler Fault Code L7 Error Common Q & A
Just below, we have a list of common questions relating to the L7 fault code on the Ideal boiler.
- What does the L7 fault code mean on my Ideal boiler?
- Is my boiler dangerous if it’s showing the L7 fault code?
- Is there a DIY fix for the L7 fault code on Ideal boilers?
- What are the NTC thermistors on my boiler, and what do they do?
- What causes the NTC thermistor not to log a rise in flow temperature on my boiler?
- How will my emergency boiler engineer be able to check to see if the NTC thermistor is damaged or faulty?
- My boiler engineer says the NTC thermistor’s connections and wires have been water damaged, what could be the cause?
- How could the heat exchanger contribute to water damage, and the L7 fault code being displayed?
- If I need a new heat exchanger in my Ideal boiler, how much is it likely to cost?
- Why would the pump fail and contribute to the L7 fault code being displayed on my Ideal boiler?
- If the pump’s flow is being restricted, will it need to be replaced?
- My emergency boiler engineer thinks the pump needs replacing, how much is this likely to cost?
- What else could be causing the L7 fault code to be displayed on my Ideal boiler?
What does the L7 fault code mean on my Ideal boiler
If your Ideal boiler is displaying the L7 fault code, it means the NTC thermistor on the flow hasn’t measured a reading that’s increased by at least 5 degrees since the boiler ignited.
When this fault code is displayed on the control panel of your boiler, it’s likely to have attempted to ignite 3 times before locking out.
Is my boiler dangerous if it’s showing the L7 fault code
If your boiler is currently not working (i.e. it’s locked out and displaying the L7 fault code), it isn’t dangerous. It only becomes dangerous if it displays a fault code, and the boiler is reset without fixing the fault.
When you reset your boiler, it should go through the same sequence again. It will try to ignite 3 times, not notice a temperature increase on the flow pipe’s NTC thermistor, and then lock out.
However, sometimes a reset can mislead a boiler into thinking the problem has been fixed. It might work intermittently for a few minutes, and it could be operating dangerously. So, don’t reset your boiler until it’s been fixed.
Is there a DIY fix for the L7 fault code on Ideal boilers
There are several fault codes where the issue can be fixed on a DIY basis. The most common is a boiler with low pressure.
However, the L7 fault code will likely require physical work on your boiler. The only people qualified to work on gas appliances are those qualified and registered on the Gas Safe Register
This becomes even more important if you are the landlord of a property. Working on a boiler without Gas Safe certification in this case could lead to large fines, and even jail time.
What are the NTC thermistors on my boiler, and what do they do
All electronic components on your boiler are monitored and operated by the printed circuit board. The NTC thermistors monitor temperature on the flow and return pipes (in ohms) and feed back these readings to the PCB. From these readings, the PCB can convert them into temperatures (in degrees).
The flow pipe NTC thermistor monitors hot water leaving the boiler. The return thermistor monitors the water that’s circulating back from the heating system, ready to be reheated.
This helps the PCB know when the boiler’s water is up to temperature. If it needs heating further, it passes the signal to the gas valve to keep supplying the burner. If water is already up to temperature, it shuts down the gas valve until the NTC thermistor gives a reading below the temperature that’s desired.
The PCB also wants to see that the differential (in degrees) between the flow and return doesn’t exceed the maximum. And of course, when your boiler fires up, it expects to see the flow temperature rise quickly.
In the case of the L7 fault code on your Ideal boiler, it’s not seeing a rise of flow temperature.
How will my emergency boiler engineer be able to check to see if the NTC thermistor is damaged or faulty
The most obvious cause of the L7 fault code being displayed would be that the NTC thermistor on the flow pipe isn’t monitoring temperatures correctly. This could due to be faulty wiring, loose connections, a faulty thermistor, or incorrect installation.
But, the potential causes of the L7 fault don’t stop there. This fault code relates to anything that affects the temperature of flow water, which could include a broken heat exchanger, faulty pump, or even the PCB.
My boiler engineer says the NTC thermistor’s connections and wires have been water damaged, what could be the cause
The first thing your emergency boiler engineer will need to do, is a quick visual inspection. If the NTC thermistor isn’t connected to the pipe correctly, it won’t be able to log readings and pass them on to the PCB.
Assuming the installation of the NTC thermistor is correct, they’ll need to check both wiring and connections. There’s a chance that these could have become damaged or worked loose. If they have, they can be repaired and re-secured to fix the L7 fault code on your Ideal boiler.
If the connections and wires show no issues, it’s likely that the NTC thermistor is faulty. Your heating engineer will be able to test the component using a multi-meter. This enables them to see if the NTC thermistor is getting power. And, if it’s not, they’ll need to fit a new thermistor on the flow.
How could the heat exchanger contribute to water damage, and the L7 fault code being displayed
If water damage has occurred, your repair engineer will need to fix the root cause, before working on the thermistor. If they don’t, the damage is likely not only to occur again, it’s likely to work its way into other expensive boiler parts too.
Lots of parts in a boiler can leak. But, parts that could be related to the heating and flow of hot water (and therefore, the L7 fault code) mean the issue is likely with the pump or the heat exchanger.
Cracks in the heat exchanger can produce leaks large enough to damage internal components. Likewise, if the seals on the pump degrade, they can leak and damage internal boiler parts too.
If I need a new heat exchanger in my Ideal boiler, how much is it likely to cost
The heat exchanger can contribute to the L7 fault code being displayed in two ways. Firstly, a cracked heat exchanger is going to leak, and cause damage to components such as the NTC thermistor’s water damage.
More importantly, if the heat exchanger is cracked, there’s a good chance it’s not operating correctly. If it’s not able to heat water, that could be the reason that the NTC thermistor on the flow isn’t detecting a change in temperature.
Why would the pump fail and contribute to the L7 fault code being displayed on my Ideal boiler
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If the pump’s flow is being restricted, will it need to be replaced
The heat exchanger is one of the most expensive parts in your boiler. Typically, you should expect to pay around £450-500 for a replacement, depending on the exact model of boiler that you own.
For this reason, you’ll want to ensure that the rest of your boiler components are in good condition. If they’re not, it will make more sense to invest in a new boiler, rather than one that’s already proving to be unreliable.
New boilers typically have a warranty of 5 years or more, and faults like this would be covered under that warranty.
Why would the pump fail and contribute to the L7 fault code being displayed on my Ideal boiler
Your heating pump is what circulates water around your heating system. If the pump is restricted in any way, it won’t be pumping hot water out of your boiler. And, that’s going to lead to the L7 fault code being displayed.
There are a range of reasons a pump might be restricted. This includes blockages in the form of heating sludge, air locks and even seized bearings.
If the pump’s flow is being restricted, will it need to be replaced
If the pump’s overall condition is good, it can usually re-conditioned.
For instance, the heating sludge (which is a build-up of rust from radiators and pipework) can be cleaned out. Your emergency boiler engineer can bleed the heating pump which will get rid of any air locks.
And, if the pump’s bearings are worn or seized, these can be replaced too. When refitting the boiler, your heating engineer will ensure that the pump’s shaft is exactly horizontal. A pump that isn’t installed with the shaft horizontal leads to premature wear of the shaft and bearings. So, this could have been what’s caused the problem in the first place.
My emergency boiler engineer thinks the pump needs replacing, how much is this likely to cost
A quality boiler pump from a leading brand like Grundfos is likely to cost around £250 to replace, including labour. The job will take roughly 1 day to complete, including sourcing parts.
What else could be causing the L7 fault code to be displayed on my Ideal boiler
As a precautionary measure, your boiler engineer should always test the printed circuit board (PCB) on your boiler.
The PCB controls all the electrical components. So, it stands to reason that if the PCB is failing, the fault codes that it’s showing and even the signals it gives/receives could all be wrong.
And, the main reason for testing the PCB, is because it’s the most expensive part in the boiler to replace. If this part is faulty alongside even one other, a better use of your money would be to invest in a replacement boiler rather than a repair.
Other Ideal boiler issues
For more boiler issues regarding the Idea Boiler then please visit the Ideal Boiler Problems And Cures page.