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Common Warmflow Boiler Problems & Repair Advice

Rob Wells
By: Rob Wells
Updated: 7th January 2022

Last Updated: 7th January 2022

Warmflow Boiler Repair

Boilers are supposed to be reliable appliances, that are kept out of the way and left alone to get on with their jobs. It's easy to even forget that the heating and hot water we enjoy on a daily basis is being provided by a boiler, until it stops working.

As you jump out of that suddenly freezing cold shower, it can be easy for the home to slide into a state of chaos. The good news is that there are many common problems that can be resolved in minutes, without the need of an engineer.

We've put together this handy guide of some of the most common Warmflow boiler problems and repair advice, to help you recognise, identify and tackle many boiler issues. If you do need an engineer though, use our free service to get quotes from reliable engineers near you.

Common Warmflow boiler problems

Boiler failing to ignite

When the flame in your boiler is failing to ignite, a red reset button will be illuminated. Seeing this, indicates that there's a fault or there isn't any fuel getting to the burner. Try resetting twice, and if this doesn't get the flame igniting again then you'll need to get an engineer to take a look.

Not getting any heat or hot water

There are several potential causes when your home isn't being provided with heating or hot water, including broken diaphragms and airlocks, failure of motorised valves, issues with the thermostat or low water levels.

Start by checking if your boiler has stopped working as a result of an issue with boiler pressure or your thermostat. If not then it's probably because of a broken diaphragm, airlock or valve which means that it may need to be replaced with a new part by a Gas Safe registered engineer.

Low boiler pressure

Firstly, check for a visible leak in the system and if you find one contact a registered engineer. If not, then you could try repressurising the system yourself but only do so if you feel comfortable and be sure to follow your heating systems' manual. Visit our guide to low boiler pressure to learn more.

Boiler switching off

If your Warmflow boiler is constantly switching itself off, it could be due to low water pressure, a thermostat issue or a lack of water flow due to a closed valve, air or the pump not circulating the water in the system properly. If you've been through all of these and can't identify the issue then it's a good idea to call out a Gas Safe registered engineer to take a look at your boiler.


Are you hearing a strange rumbling noise, as if a kettle is boiling somewhere? When limescale or sludge builds up on your boiler's heat exchanger you can get something called kettling. As these build up in your boiler, they can restrict the flow of water within the heat exchanger. This can overheat the water, causing it to steam and boil.

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Which Warmflow boiler problems need an engineer?

Once you've identified a problem with your boiler, you need to know what the potential cause is and whether you'll need an engineer. Use our table below to help you know exactly what to do.

Problem Possible cause Do you need an engineer?
No heat or hot water Can be caused by several things including broken diaphragms and airlocks, failure of motorised valves, issues with the thermostat or low water levels Yes
Leaking and dripping Most likely to be a broken internal component but it will depend where the water is leaking from Yes
Banging, whistling or gurgling noises Air in the system could be causing this, otherwise it could be that the water pressure is too low Yes
Pilot light goes out The thermocouple could be broken which is in turn stopping the gas supply Yes
Losing pressure Could be a water leak in the system, the pressure relief valve needs replacing or due to recently bleeding radiators Only if there's a leak
Frozen condensate pipe This fault should be displayed on your boiler as an error code or warning notification Yes
Thermostat issues Thermostat could be turned off or not set to the correct settings (time etc.) Consider replacing
Kettling Limescale or sludge building up on the heat exchanger Yes
Radiators not getting hot Sludge or air building 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 or the pump not circulating the water in the system properly Yes

Warmflow boiler warranty

Warmflow boilers are guaranteed against defective parts and faulty workmanship for 24 months from the date of manufacture. In the case of Combi boilers, the water jacket and thermal store are guaranteed for a total of 5 years from the date of manufacture but this doesn't include the burner, labour, handling or shipping. Get to know their warranties even better with our guide to Warmflow warranties.

An annual Warmflow boiler service will help to keep your boiler running to its safest and most efficient levels for as many years as possible. This is also required under the terms of the warranty or it will become invalid.

Boiler insurance and ongoing cover

If your Warmflow boiler warranty has expired, then boiler insurance could be worth considering. When comparing insurance, the best ones will include an annual service and safety inspection, so keep an eye out for them. You can take out insurance with your energy supplier.

Could it be time to replace your Warmflow boiler?

If your Warmflow boiler has been providing a reliable service to your home for some period of time, it could be worth considering a new one. If you live in a detached home, your potential savings are as much as £365* a year. Take a look at the table below to see how much you could be saving depending on your current boiler rating and property.

House Type G ( 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 engineer to replace a Warmflow boiler?

If replacing your Warmflow boiler is something you'd like to go ahead with, that means you'll now need to think about deciding who will do the installation.

Whoever you get to replace a boiler must be Gas Safe registered, that's the easy part. The decision you'll have to make, comes down to a national company or local engineer, so which is right for you?

With national companies, you'll not only be getting your boiler replaced but be offered extra services like ongoing boiler cover and big brand protection, always a plus.

Local engineers, however, can offer extremely competitive rates with a personal service so you can talk with the very same person from the first phone call to the last.

We don't recommend going with the first engineer you talk to so it's a good idea to get a quote from up to 3 engineers to give you the best chance of getting the perfect deal for you.

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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