Ideal L1 fault

L1 Ideal Boiler fault code – How to fix!

As per the boiler manufacturers, Ideal, the L1 boiler fault code relates to a lack of water flow or an overheating of the hot water flow temperature.

What is the hot water flow pipe of my boiler?

The flow pipe on your boiler is the one where hot water leaves the boiler for your central heating system after it’s been heated. This will be hotter than other pipes and will show the Ideal boiler fault code L1

There are thermistors on the return and flow pipes on Ideal Logic boilers. These sensors measure resistance based on water temperature. This resistance reading is sent via the printed circuit board (PCB).

The boiler will continue to function if the temperature is within its operating range. The L1 Ideal boiler fault code will display if the temperature rises above or drops below the operating range.

How dangerous is the Ideal boiler L1 fault code

Your Ideal boiler should show a boiler fault code and then to protect itself it will lock out. The lock out means the boiler will cease to work, and this usually makes the boiler safe.

Ideal boiler fault codes are there for your and your boiler’s protection. If your boiler shows any fault code but doesn’t lockout it is best to turn it off and call a Gas Safe registered engineer.

The boiler’s components are protected by the lock out in case of damage. It also serves as a safety device and will stop the boiler’s power.

How can I reset my boiler in order to clear the L1 fault code

As we’ve mentioned, the safety lock-out mode function is a safety measure. Therefore, you shouldn’t be resetting your boiler until a Gas Safe registered engineer has the problem fixed.

Only a Gas Safe engineer should work on boilers so do not try and fix the boiler fault codes yourself as it may cause more issues, and if you have a faulty gas valve, you could cause a leak.

What causes the Ideal L1 fault code to appear?

As with any ideal fault code, the issue can usually be caused by a number of different things, but however, it does narrow your problems down to the following reasons:

This could be the root cause of your problem.

  • Faulty flow thermometer
  • Limescale buildup on the flow pipe
  • Broken heating pump
  • Malfunctioning PCB

What happens if there is a flow thermistor fault?

If the flow thermistor on your Ideal boiler is faulty, the readings it’s passing on to your PCB could be incorrect. In this case, the temperature reading might be much higher than it actually is.

This is recognised by the boiler’s PCB and locks it out. The PCB will the give out the Ideal boiler fault codes relating to the problem, in this case L1

What is the problem with my boiler’s thermistor?

Generally, a thermistor issue is caused by wear and tear due to a boilers age. The vibrations from the boiler could have worked loose or damaged the connections to the thermistor, causing it to pass on intermittent readings to the PCB.

What is the cost of repairing a flow thermistor problem on an Ideal boiler?

Repairing this issue isn’t that difficult and this is one of the cheaper repairs on boilers. The thermistor will cost £40-50 on its own. You should expect to then pay a Gas Safe engineer £80-£100 to come out to check your boiler and figure out what is going on and then fix it.

The cost of the repair will run between £120-£150. It is expected that the work will take about an hour for a boiler engineer.

Limescale in a central heating system

Central heating systems hold their pressure thanks to the water that they contain. This water isn’t purified, as it comes straight from the mains supply.

Mains water can contain a lot of minerals, some more than others. These minerals can settle on central heating systems.

Limescale tends to settle on the heat exchanger most, but also the flow tube.

What happens if limescale builds up in my boiler’s flow pipe?

Where limescale settles, the water tends to burn a little hotter than it does in the rest of the heating system.

Although it is not dangerous, this can pose a problem. The flow thermistor monitors the flow water’s temperature. If limescale settles near the temperature sensor, it will be reading a temperature that is higher than it should.

The temperature reading at your thermistor may be too high because of limescale, but the rest might be the right temperature.

Problem is, the PCB can only recognize the temperature reading from the thermometer. It will not recognise the water temperature.

What can I do to solve my limescale issue?

Manufacturers such as Fernox and Sentinel produce limescale removers. They’re sometimes called heating silencers. This is fluid that you add to your central heating system. When they come into contact with limescale they start to break it up keeping your water flowing more freely.

You can catch it in a limescale remover (a small filter), or you can flush the system to get rid of all limescale. A magnetic boiler filter will also be installed.

If that doesn’t solve the problem, then the pipework or thermistor responsible may have to be replaced.

Could my central heating pump cause the L1 fault code to be displayed?

Your heating pump is what circulates the water around the central heating system to your radiators. So, if there’s a water circulation fault, this central heating pump needs to be checked.

You can also link it to an overheat. The boiler will heat up too much if the water isn’t circulated quickly enough or at all.

A Gas Safe engineer will first check that the pump is set to the correct setting. The Grundfos UPS2 pumps, which are newer than the UPS1, have three-speed settings. You will need the fastest flow setting if you live on a large property with many radiators.

An engineer will also check to make sure the pump isn’t blocked. The engineer will first bleed the pump with the bleed screw. A pump with an air lock can restrict its circulation.

While they are removing the boiler casing, they will take apart the pump and clean it. These debris are caused by heating sludge, which builds up in the heating system.

If the shaft and bearings of the pump are in good shape, it can be re-fitted to clear the L1 fault code from your Ideal boiler.

How can I stop this from happening again?

It’s likely this debris has come from rust. That breaks off the inside of radiators, towel rails and copper pipe.

This is the quickest and most effective way to avoid it.

  • To get rid of central heating sludge, fill the system with a central heating inhibitor.
  • Add a limescale inhibitor to the heating system.
  • To catch any debris, install a magnetic boiler filter

What does the PCB have to do with L1 fault codes?

If the boiler engineer still can’t find why the Ideal boiler is showing L1, there’s a good chance it’s due to a faulty PCB or Printed Circuit Board.

Your boiler’s control panel is made up of the PCB. Your boiler will not work properly if it isn’t working correctly.

It needs to read the readings from a thermistor. It may also lock the boiler if it isn’t translating the readings correctly.

What can a boiler engineer do to check if there is a problem with the PCB?

The first thing they can do is do a visual check or inspection. They’ll be looking for loose wiring and any possibilities of other faults such as burnt-out connections. If they find any, these need to be fixed right away.

They will need to test the unit using a multimeter if nothing happens with a visual inspection. This will tell you if the PCB is defective.

You will need to replace the PCB in your boiler if it is defective. A new PCB will generally cost between £400 and £500 depending on which model boiler you have.

Do I need a new boiler?

If you boiler has started showing L fault codes then it may be time to consider how old it is. Older boilers can start to cost money in terms of repairs and a higher gas and energy bill. An Ideal fault code and other boiler issues could mean the start of more problems if it is over 10 years old.

Speak to a qualified engineer when you get your annual service, they may give you a better idea of what state your unit is in. If your error code is worse than L1, then why not get a quote online now in under 20 seconds to see how much a new boiler costs.

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