Ideal boiler F1

Ideal Boiler F1 Fault: Complete Guide on How to Fix

Last updated on June 10th, 2024

An Ideal boiler F1 fault will cause your boiler to lock out so you have no heating or hot water. This can be very frustrating, especially on a cold winter night.

I have been repairing boilers full-time for over a decade and have fixed my fair share of Ideal boilers.

In this post, I’ll show what to do when you have an Ideal boiler F1 fault and how to get your boiler going again.

How to Fix F1 on Ideal Boiler

The Ideal boiler F1 fault indicates low pressure. You must learn how to repressurise a boiler to fix it.

Repressurise Ideal boiler

You need to check the pressure gauge and if it’s low, repressurise it until it’s at 1 to 1.5 bar.

It could be other problems causing the F1 low water pressure fault code, but a leak is by far the most common reason for your Ideal boiler pressure dropping.

The Ideal boiler F1 fault code should disappear when the boiler is repressurised, and you should hear the pump start to circulate the water in the boiler.

How to Reset an Ideal Boiler

The first thing I would check on an Ideal boiler that is not working, no matter what fault code is showing, is to check the pressure and reset the boiler.

Knowing how to reset an Ideal boiler is the simplest way to get your boiler working again as it might have locked out without any problems.

how to reset an Ideal boiler
How to reset an Ideal boiler

To reset an Ideal boiler, you must turn the right-hand knob clockwise as far as it will go and hold it there for a few seconds, then release it.

Ideal Boiler F1 Error Keeps Happening

If your boiler has regular pressure loss, showing F1 and going to lockout, you most likely have a leak on the boiler or central heating system that needs fixing.

There are other reasons for the F1 error to keep happening. You might need to recharge the expansion vessel and/or the pressure relief valve needs replacing.

Ideal boiler pressure low

If the boiler pressure is dropping straight away after repressurising, then you must have a serious leak or an open-ended pipe on the heating system. This must be found and fixed to get your boiler working again.

How to Repressurise an Ideal Boiler

To repressurise an Ideal boiler, you must find the filling loop. If it’s a built-in filling loop, it will have two blue or black handles under the boiler.

Both handles must be turned to open and then closed when the pressure reaches 1 to 1.5 bar.

How to repressurise an Ideal boiler

If it’s an external filling loop, it will probably be on two of the pipes under the boiler. A filling loop will have two valves with either one or two black handles and a flexible hose connecting them together.

You must open both valves to repressurise the boiler, then close them both when it is repressurised.

Filling loop open
External filling loop

You should be able to hear the water filling the central heating system when both valves are open, if not, then the filling loop might have problems, or the house’s mains water could be turned off.

Other Causes of Ideal Boiler F1

Other causes for the Ideal boiler F1 fault code, if it’s not low water pressure, could be:

  • Pressure sensor faulty
  • PCB faulty
Ideal Logic boiler heating on

Ideal Boiler Guides


An Ideal F1 fault can be easily fixed by repressurising the boiler so no need to call in a gas engineer.

If your boiler pressure keeps dropping, you will need to find and fix the problem first or you will keep getting L1 on your boiler and not be able to use it.

Feel free to leave feedback or ask me any questions in the comment section below and I’ll try my best to help.

Please share this post if you found it helpful.

Ideal Boiler F1 Fault FAQs

Why does my Ideal boiler keep losing pressure?

Your Ideal boiler keeps losing pressure because you most likely have a leak on your central heating system, which could be at the boiler.

Another reason your Ideal boiler keeps losing pressure could be an expansion vessel problem, or the pressure relief valve might be letting by.

How long should an Ideal boiler last?

An Ideal Boiler, like most modern boilers, should last at least 10 years. You might get 15 or more if serviced regularly and well maintained, but I have replaced boilers that are less than 10 years old.

Sometimes it’s the environment around the property that determines how long a boiler lasts. If your boiler is over 10 years old and you are starting to have regular problems with it, it might be worth getting some quotes for a new boiler.

What happens if the condensate trap is blocked?

If your Ideal boiler condensate trap gets blocked, the condensate wastewater will not get discharged and this will cause your boiler to lock out and stop working.


  • Steven Reid

    I am a full-time plumber and Gas Safe registered engineer. I incorporated Housewarm Ltd. in 2011 to provide heating and plumbing services to homes in Newcastle upon Tyne, England. I now blog about what I've learned over the years to help DIYers and plumbers.

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4 thoughts on “Ideal Boiler F1 Fault: Complete Guide on How to Fix”

  1. Roisine

    Hello, I have an ideal logic max system s18ie installed 2 years ago. House is a bit older and have a hot water tank in the hot press. I have no pressure in my boiler and fd fault showing. There is no filling loop at the boiler and cannot see at the tank either. I am stumped and feel I’m missing something fairly obvious but can’t figure out where it is.

    1. Steven Reid

      Hi Roisine, there must be a filling loop somewhere. On a system boiler like yours, it’s usually in the cupboard where the hot water cylinder is. It won’t be at the boiler as there’s no water supply on your type of boiler.

      1. Roisine

        I thought that would be the case and can’t see anything. At the hot water tank there a red lever on one pipe, a red knob higher up on one of the pipes, an identical red knob further down and a smaller red knob very close to a pipe attached to the tank itself. I can’t see anything else. I can’t unfortunately attach a picture as that may make more sense.

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