Faulty Heat Exchanger On A Boiler - AWP Boiler Installations

20 November 2024

Causes, Costs & How to Fix

If you think you have a faulty heat exchanger, or it is leaking from your boiler installation, the next question you will want to know is the possible cost of boiler repairs or a replacement boiler. The answer to this unfortunately can be very expensive, possibly meaning the cost effective option is to replace it with a new boiler. With new boiler warranty being attractive, often a faulty heat exchanger can result in being beyond economical repair or deemed written off. For a more comprehensive understanding of heat exchangers the following information will help you understand potential costs, boiler repairs or replacement boiler options.

Can You Repair a Heat Exchanger?

Consulting a fully Gas Safe registered heating engineer and obtaining quotes for boiler repairs to replacement heat exchangers is the first port of call, however you may find it will be more cost effective to have a new boiler installed complete with warranty. For quotes to have a new boiler installed by a Worcester Bosch accredited installer you can contact us, we offer extended warranty up to 12 years on some of our Worcester Bosch boiler installations.

How Much Is Boiler Heat Exchanger Replacement?

Although it is good news you can replace your boilers faulty heat exchanger, the bad news is the cost of replacing the heat exchanger will start at around £500. This is why investing in a new boiler is generally considered a better option. A new Worcester Bosch with up to 12 years warranty, in our opinion, is a more cost effective way to go than replacing the old heat exchanger.

What Is a Heat Exchanger in a Boiler?

A heat exchanger is what converts a gas boilers heat from gas, to water. As the water flows through the heat exchanger absorbs the heat, then it will circulate through your central heating system to your radiators and your hot taps for hot water. As the water loses heating through the return pipe, it makes its way back through the boilers heat exchanger then heats up to go back around the central heating circuit. This is why the heat exchanger is a vital part of the gas boiler and can be such an expensive boiler part to replace.

Boiler Heat Exchanger Leak

A leaking heat exchanger can be a common issue with older boilers, due to the sludge and magnetite travelling around the central heating circuit. A fully Gas Safe registered heating engineer can diagnose it is the heat exchanger that is leaking on your boiler installation and your best option of how to fix it to prevent it happening in the future. It is possible power flushing may be advised to clear out your central heating system.

Problems with Limescale Build-Up in the Heat Exchanger

Hard water areas can be an issue when it comes to your boiler and in particular your boilers faulty heat exchanger. The build up of limescale can get into the parts on your boiler. A limescale reducer can be worth installing if this is the case.

Unusual Noises: Any kettling, whistling, banging or gurgling noises from the boiler installation can indicate your boiler and heat exchanger is overheating.
Boiler Lockouts: Each boiler has an NTC thermistor that monitors the water temperature. If it is too high, it will cause a boiler lockout. This will happen when overheating, or with a faulty heat exchanger.
Heat Exchanger Leaks: Hotspots can cause cracks in the heat exchanger, which in turn will then cause your heat exchanger to leak. In this case often you may be better with a replacement boiler.

Ways to Fix and Prevent Limescale Build-Up

Preventing limescale build-up is often more effective than addressing it after it occurs. Here are a few cost-effective strategies:

Central Heating Sludge

Whilst it is limited limescale that originates from the boiler, sludge and debris in your central heating system accumulates from rust and magnetite inside the system. This sludge can usually be the main issue as to why heat exchangers begin to fail.

Unusual Noises: If limescale has created a hotspot on the heat exchanger. You may hear kettling and whistling noises which cause steam bubbles from the overheated water.
Boiler Lockouts: Similar to limescale, this can cause the central heating system and boiler installation to lockout, if the water flow is restricted.
Bleeding Radiators: When you bleed your radiators, if the water is discoloured or black this can strongly indicate your central heating system is sludged up and in time this may cause a blockage.

Ways to Fix and Prevent Heating Sludge Build-Up

A Gas Safe registered heating engineer can help give you advice with the best options to prevent your central heating system building up with sludge. Power flushing or a chemical flush is often a common recommendation to prevent the build up of sludge and magnetite. The Benefits Of A Central Heating Powerflush.

Heat Exchanger Repairs

With a faulty heat exchanger, boiler repairs can become very expensive. Usually replacement boilers are the best way to go if you need a new heat exchanger. A new boiler with a flushed out central heating system would usually be highly recommended.

How Much Does It Cost to Replace a Heat Exchanger?

Typical costs to replace a faulty heat exchanger can start from around £500, that is why generally a new boiler that carries an extended warranty can be the most cost effective way forward, rather than to replace the faulty heat exchanger.

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