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One of the most common places you’ll find a heat exchanger is within your boiler. It’s the crucial component which produces hot water and heating for your property. Essentially, if you’ve found yourself with a faulty heat exchanger, you’ll soon find yourself without hot water or heating.
For that reason, it’s important to take good care of a heat exchanger to ensure your boiler is running at peak efficiency, saving you money on costly repairs. Unfortunately, not many homeowners know what a boiler heat exchanger is or how to keep it maintained.
We’ve compiled a helpful guide on understanding and maintaining boiler heat exchangers, as well as spotting issues that you’ll need to act on to keep your boiler functioning at its best.
In simple terms, a heat exchanger allows energy (such as heat) to pass from one liquid or gas to another without the two fluids ever having to touch. This is a much more effective heating method than simply combining hot and cold water together.
A boiler heat exchanger, in essence, can be thought of as a long piece of pipe which is coiled up. The water in your heating system is pumped through this coiled pipe, hot flue gasses from the burner pass over the surface of the pipe and heat the water as it passes through.
A combi boiler (or combination boiler) provides both central heating and hot water within the same system. Without a working heat exchanger in your combi boiler, you won’t receive any hot water or heating.
Usually, a combi boiler will have two heat exchangers - one for central heating and one for hot water.
As you can imagine, heat exchangers must sustain a high amount of stress when intense heat is consistently applied to the material. The most common materials you will find are stainless steel and aluminium:
Aluminium
Aluminium heat exchangers are lightweight and have a high thermal conductivity. The material itself is highly flexible and can be cheaper than stainless steel to install. Aluminium heat exchangers are often smaller than stainless steel types. The Aluminium is designed to be resistant to corrosion over the design life of the product
Stainless steel
Stainless steel heat exchangers are desired for their durability and very high resistance to corrosion, meaning they often maintain a longer lifespan than their aluminium counterparts. The stainless steel includes a high amount of chromium in order to be highly corrosion resistant which can impact the durability of the material.
There are two types of boiler unit which function slightly differently due to the number of heat exchangers it includes.
Non-condensing boilers
Non-condensing boilers only have one heat exchanger and have a much higher carbon footprint than condensing boilers. When non-condensing boilers burn gas to create heat, the waste gases are disposed of through the exit flue, rather than recycled.
Condensing boilers
Condensing boilers have a much more efficient heat exchanger design, it still uses the same basic principle of the coiled pipe, but it can extract much more energy from the flue gasses passing over it. Put very simply it’s a longer coil of pipe which means more energy can be transferred to the water passing through it. This means that very little energy is lost through the flue.
It is now a requirement of the UK Government that all newly-fitted boilers must be a condensing unit, though exemptions may be granted.
Whether the material is aluminium, stainless steel or otherwise, we recommend that your heat exchanger is checked every 12 months by a gas safe engineer to identify issues before they reach urgency. Without a professional review, it can be difficult to know the ‘health’ of your heat exchanger, though there are some clear signs we recommend looking out for.
Keeping a clean and maintained exchanger will prolong the life of your boiler. This rings true for whichever boiler or type of exchanger you have, as there is always the risk of dirt or debris from your radiators.
You’ll need to get in touch with a Gas Safe registered engineer to clean the device for you. Never remove a heat exchanger yourself, as it is not safe to do so and you could cause unnecessary costly damage to your boiler.
Limescale
Whilst we strongly recommend you do not remove or clean the device yourself, you can take steps to reduce the risk of limescale build up. Talk to your heating engineer about installing a limescale reducer to act as a filter or use a limescale silencer to remove build-up if the problem is further advanced.
Central heating sludge
Central heating sludge causes rust and debris to infiltrate the water. It is recommended that your heating system receives a flush every 5 years to reduce build-up of contamination and damage to your heat exchanger. A filter can also be installed to help catch debris as it passes through a filter.
