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Energy Saving

Gas hot water boiler replacement

Considering gas boiler replacement? In the first place, if a green energy option isn’t right for you, we can help you choose the right gas condensing boiler for your need. By and large, the type of boiler you’ll want for a public swimming pool is very different from a guest house or cafe.

It’s important to realise that all new gas boilers are condensing, even domestic combi boilers. This technology makes better use of the heat generated from fuels such as gas or oil.

What is a gas condensing boiler?

Gas condensing boilers are highly efficient and work by extracting heat from exhaust gases.  They reuse it and indeed, this makes them up to 25% more efficient than non-condensing boilers. Your new boiler could reach up to 99% efficiency. 

If you also consider taking a green gas or mixed green gas tariff, then you’ll also be reducing your production of greenhouse gases.

They are also considered a lot safer than older systems. 


Certainly, Landlords, or those responsible for managing student accommodation, have serious legal obligations to ensure that gas boilers are safe. If they aren’t, replacement is necessary. In fact, safety obligations apply to anyone responsible for gas boilers.

STOP! Think about green alternatives first

On the other hand, if you want to reduce your energy costs and reduce your emissions, now is a good time to think about alternatives to polluting natural gas. 

Furthermore, with not only national net-zero carbon legislation in play but also many Councils pledging to be carbon net zero by 2030, you should above all consider a different approach to your boiler replacement.

Specifically, in 2019,  270 councils had already declared a climate emergency. 

To put it another way, could you find room outside for an Air Source Heat Pump or Ground Source Heat Pump? If not, should you consider a green gas tariff or mixed green gas tariff?

How about a biomass boiler? In fact, both these options are particularly good if you’re not on mains gas. In commercial applications, Heat Pumps and Biomass boilers will both give you 20 years of income from the Renewable Heat Incentive (RHI). 


As an illustration as to why you should consider alternatives to gas boilers, there’s Energiesprong / ZEBCat (Zero Energy Buildings Catalyst). This is the  net-zero carbon model from the Netherlands, which is being applied to social housing stock by councils. They are ditching gas boilers in favour of newer, energy-efficient and renewable technology. In fact, gas is completely out, altogether.

In reality, if you invest in a fossil-fuel technology now, you could find yourself replacing it years ahead of time. To clarify, Councils are replacing gas boilers in their own housing stock. How soon before they make your business do the same to meet the UK’s legal climate obligations?

Get the right advice and help first

If you’re in two minds, IU Energy can help you understand the options and help you with net zero carbon transition. You may also end up benefiting from that 20-year government renewable incentive funding we referenced, not to mention the enhanced capital allowances (ECA) which may be available. This can really add up and may improve your profits.

However you decide,  IU Energy is qualified and highly experienced in surveying and installing all types of commercial gas condensing boilers. Equally, we are especially good at energy-efficient and renewable technology installation. We are trusted by clients in –

  • Care homes
  • Construction
  • Councils
  • Farms
  • Healthcare 
  • Hospices
  • Hotels
  • Places of Worship
  • Restaurants
  • Retail
  • Schools
  • Sports Stadia
  • Student Accommodation

Further information

You can download a gas boiler replacement Technology Information Sheet here.

Below are some of our case studies for projects we have conducted using efficient gas boiler replacement, followed by FAQs.


All modern boilers use condensing technology.

A combi-boiler is a specific type of heating system. It combines water heating with central heating in one unit and takes up much less space than a traditional boiler installation. A combi-boiler works by heating water directly from the mains outlet (as opposed to feeding in from a water tank). It also means that your water is always delivered with mains pressure.

This technology is only suitable where the demand for hot water is low.

‘Condensing’ boilers use technology that improves the efficiency of modern boiler systems. It collects the heat or vapour from flue gases and reuses/recycles it, something which makes some condensing boilers as much as 25% more efficient than non-condensing boilers, reaching up to 99% efficiency. It is increasingly fitted in combi boilers.

Most commercial applications benefit from a full system boiler where water is stored in a tank. System boilers provide space heating directly, whilst also supplying hot water to a storage cylinder. They have most of the individual components of a heat and hot water system built into the boiler unit, so whilst they do require a separate cylinder, unlike a conventional boiler they don’t also require a cold-water tank.

Hot water is pumped through the radiators and the hot water cylinder, delivering a faster response, which could be more economical and mean lower running costs than a conventional boiler.

We recommend a service package which includes annual servicing. This is necessary for both reliability and the safety of the plant.

If you’re in Food, Healthcare, Beverages, Paper, Packaging, Pharmaceutical, Petrochemical, Feed Mills, Agriculture, Laundries or Textiles, please contact us for a more detailed conversation as your system will necessarily require more planning. 01252 26 26 26

The general lifespan of a boiler is around 10 to 15 years. While this is an average, your boiler may last longer if you take good care of it.

You should decide to replace your boiler when repairs become too expensive or start mounting up. Opting for a new boiler at this point should save you money in the long run.

To find boilers that are economical, look for their ENERGY STAR rating. A well rated boiler should run very efficiently, whereas a poorly rated model may be more cost effective to replace in the long run.

You should find that all modern boilers are more economical when compared to older models.

How much energy is your business currently wasting?

IU Energy is a multi-award-winning business, providing comprehensive energy management services to its B2B clients, including energy reduction solutions, renewables and independent energy procurement.


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