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Common Intergas Boiler Problems & Repair Advice

Rob Wells
By: Rob Wells
Updated: 27th March 2024

Last Updated: 12th January 2022

Intergas Boiler Repair

While Intergas boilers are extremely reliable appliances, should the worst happen this guide is here to take you through Intergas boiler problems and provide you with repair advice, so you know exactly what to do. Many common boiler problems don't even need the expertise of a heating engineer but if one is needed (and if in doubt always get in touch with an engineer), you can get free boiler repair quotes using Boiler Guide.

Common Intergas boiler problems

Low boiler pressure

Without sufficient boiler pressure, your Intergas boiler won’t be able to ignite. Checking the boiler pressure couldn’t be easier, simply take a look at the pressure gauge – if the needle is below 1 bar then your Intergas boiler is low on pressure.

Increasing Intergas boiler pressure

A sudden drop in pressure could indicate a leak in the system, which can cause damage to components within the boiler, not to mention your home. If there’s any indication of water leaking, then you’ll need to hire a Gas Safe registered engineer to fix it before the pressure can be increased.

Once the leak has been fixed, if there was one, it’s possible to increase boiler pressure yourself by following the steps in our guide to low boiler pressure. If in any doubt though, don’t hesitate to contact a professional.

Frozen condensate pipe

A frozen condensate pipe can occur during the colder months as this pipe leads outdoors to a drain to dispose of acidic water. When the condensate pipe freezes, it can cause a blockage which will prevent the boiler for working.

Thawing a frozen condensate pipe

If your condensate pipe has frozen, you might want to try thawing it out yourself, which you can do using our tutorial. If you feel unsafe doing so you should call out a Gas Safe registered engineer.

Boiler overheating

An boiler that’s overheating can eventually lead to some serious damage if left. Fortunately, the fix is fairly simple and something you can do without hiring a Gas Safe registered engineer.

Intergas boiler overheating fix

Air in the system is one of the most common reasons for a boiler overheating. In the same way as a physical blockage, air in the system, or ‘airlocks’, can prevent water from circulating around the heating system. To remove this air, you can either hire a heating engineer to bleed your radiators or follow steps to bleeding a radiator yourself.

No flame

When you turn on your heating or use the hot water tap, the circuit board in the boiler (or PCB – printed circuit board) will tell the gas valve to open, which will provide gas to ignite the flame. When the 4 error code appears, it means that the PCB is unable to detect this process.

Fixing no flame on an Intergas boiler

Seeing the Intergas 4 error code isn’t a simple one to resolve and you should never attempt to fix it yourself. In this case, the issue could lie with the flame sensor or gas valve. Depending on the issue a heating engineer might be able to repair them but there’s a chance they could need replacing altogether.

Fault detecting flame

When your boiler gets to work, a flame ignites to heat up the water. When this happens a flame sensor tells the printed circuit board (PCB), which is effectively the ‘brain’ of the boiler, that the flame is working.

So, the flame could either be lighting but going undetected, or it might not be igniting at all.

Flame detection fault fix

There are many reasons why you could be seeing the Intergas error code 6, all of which should be looked into by a Gas Safe registered engineer:

  • Low gas pressure
  • Faulty gas valve
  • Blocked flue or condensate pipe
  • Issue with the flame sensor
  • Debris in the burner

The only exception to this is if the condensate pipe has frozen, causing a blockage. This is most likely after a period of freezing cold weather and you can find out how to fix that earlier in our list of Intergas boiler problems.

Radiators not heating up

Your radiators not heating up can be down to a number of reasons, but the two most common are sludge or air build-up in the system and unequal distribution of heat. If only the bottom of your radiator is getting hot, you may need to bleed it.

Bleeding radiators

Bleeding a radiator is fairly straightforward and our guide to bleeding radiators can take a you through the steps. If you don't feel safe bleeding the radiators yourself then you should contact an engineer.

Hearing strange noises

Any strange noises you hear coming from your boiler tends to be caused by air in the system or it’s kettling.

Fixing a noisy boiler

If there’s too much air in the system, you’ll be able to tell because your radiators won’t heat up properly. To clear the air, you will need to bleed the radiators. Kettling is the term used to describe a sound resembling a boiling kettle coming from the pipes. This happens when sludge, limescale and other debris builds up, blocking the water, causing it to boil, steam and whistle like a kettle. Removing this build-up requires a heating engineer to perform a powerflush.

To find the cause of your noisy boiler, use our guide to central heating noises.

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Which Intergas boiler problems need an engineer?

Not all boiler problems will need the trained eye of an engineer and can be done yourself, use the table below to know when you should be contacting an engineer.

Problem Possible Cause Do you need an engineer?
No heat or hot water Broken diaphragms and airlocks, failure of motorised valves, issues with the thermostat or low water levels Yes
Leaking and dripping Most common cause is a broken internal component but it will depend where the water is leaking from Yes
Banging, whistling or gurgling noises A common cause is air in the system, alternatively it could be that the water pressure is too low or it's kettling Yes
Pilot light goes out Could be a broken thermocouple which is stopping the gas supply Yes
Losing pressure There could be a water leak in the system, the pressure relief valve needs replacing or the radiators have been bled recently No, unless there's a leak
Frozen condensate pipe Your boiler should display a fault code or warning notification Yes
Thermostat issues Thermostat may be turned off or not set to the correct settings (time etc.) Consider replacing
Kettling Limescale or sludge building up on the boiler's heat exchanger Yes
Radiators not getting hot Sludge or air build up in the system or an unequal distribution of heat Your radiators will need to be bled which doesn't require an engineer but if you don't feel like carrying out the task yourself
Boiler keeps switching itself off Could be low water pressure, a problem with the thermostat or a lack of water flow due to a closed valve, air in the system or the pump not circulating the water in the system correctly Yes

Intergas boiler warranty

As standard, Intergas boilers come with a 12 month warranty but depending on the model you have installed the warranty can extend from 3-10 years. Take a read of our complete guide to Intergas warranties to find out even more about what they offer. A boiler warranty is well worth having as you’re covered should anything go wrong so keep it valid by arranging an annual Intergas boiler service by a Gas Safe engineer.

Boiler insurance and ongoing cover

When your warranty has come to an end you might want to consider covering your boiler with boiler insurance. You can easily take this out with your energy supplier but there's no obligation to do so. When comparing boiler insurance, the best ones will offer annual services and safety inspections.

Is it time to replace your Intergas boiler?

Have you had your Intergas boiler for quite a few years? If you have, potential savings of £365* a year in a detached home may make you want to think about getting a new one. Take a look at the table below to see how much you could be saving depending on your current boiler efficiency rating and property type.

House Type G (< 70%) F (70-74%) E (74-78%) D (78-82%)
Semi-Detached £240 £170 £150 £135
Detached £365 £255 £205 £165
Detached Bungalow £190 £135 £120 £105
Mid Terrace House £205 £145 £130 £115
Flat (Mid Floor) £95 £65 £60 £50

Figures are for England, Scotland and Wales only*.

Finding the best boiler installer

If you like the sound of a new boiler then you need to choose who to replace it, which can be a big decision. In the end, your choice will come down to either a local engineer or a national company.

Local engineers can offer very competitive rates and you'll be getting a very personal service from the same person throughout your communications. To make sure you're getting the best deal, it's a good idea to get a quote from more than 1 engineer, we recommend getting up to 3.

Send us an enquiry today to receive free quotes for a new boiler and find trusted engineers near you with our free service.


Data Source: Energy Saving Trust, Heating Your Home: Boilers (2022)
*Based on replacing an old gas boiler with a condensing A-rated boiler with thermostatic radiator valves, programmer and room thermostat in a detached home. Figures are based on fuel prices as of November 2021.

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Rob Wells

About the author

Rob Wells

Rob is another of our resident home heating experts. He manages our external partnerships, making sure you get the most up to date information.

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