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Flue Gas Heat Recovery is a device that sits neatly between boiler and flue.


It collects any remaining heat in the flue gas which would normally go through the flue, into the atmosphere and be wasted. This extra heat is then recycled back through the boiler to give it a head start when heating up the incoming cold water.


How does Flue Gas Heat Recovery (FGHR) work?


The waste flue gases pass through the FGHR device and any heat that remains is extracted by specially designed heat exchangers inside. This heat is then reused to pre-heat water coming into the boiler from the cold mains supply. This significantly reduces the amount of gas required by the boiler to heat the water, which means lower energy bills for the householder and greater carbon savings.

FGHR is a sealed-for-life unit that has no moving parts and does not require any maintenance other than a visual check during a normal boiler service. And it has no controls or settings for the user to worry about.  

An additional benefit of the device is that, as the flue gases leaving the FGHR device contain considerably less moisture and hardly any heat, the amount of pluming from the outside flue terminal is significantly reduced.


What are the benefits of Flue Gas Heat Recovery (FGHR)?


  • Increases boiler efficiency, saving between 37 and 50 per cent of the gas used to heat hot water annually (according to tests conducted by an independent scientific test house)
  • Reduces water usage in the dwelling - helps to reduce the amount of wasted lukewarm water that a boiler produces waiting for the water at the tap to get up to temperature. It produces useful hot water quicker
  • Increases the hot water flow rate
  • Easy to install – no controls, settings or moving parts; maintenance free and does not require servicing
  • Low carbon solution
  • Less nuisance ‘pluming’ from the flue terminal.

Related FAQs

Should I turn off my boiler in the summer?

Generally, it is best to keep your boiler switched on even during the summer months, however this can depend on your home and your circumstances.

Is a condensing boiler a combi boiler? 

Is a condensing boiler the same as a combi boiler? The short answer is yes. However, there are 3 types of condensing boilers.

Why should I get the water in my central heating system cleaned?

If your boiler breaks down due to sludge in the system, the repair work is not covered under your warranty and can lead to expensive repair bills as a result.

Why should I have a filter fitted?

Many boiler breakdowns occur due to sludge in the heating system. A magnetic filter is an effective way of preventing this sludge from accumulating, and may prevent costly breakdowns at a later stage.

How often should I have my boiler serviced?

We advise you have your boiler serviced every year in accordance with the manufacturer’s instructions and to keep your warranty valid.

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