Buying and installing a new boiler for your home

TIP 1: A boiler is an investment in your home

We may not realise but a boiler is one of the most high value purchases you will make for your home, and its not the place to be cheap about it .

Looking at it as an investment, more than just another cost, will help you make the right decisions.

On bigger purchases one of your first thoughts is probably, “is it reliable? I’m putting a lot of money into this !”

Your new boiler needs to be reliable and have great back up from the manufacturer and your installation company.

There is nothing worse than paying a lot money for a new boiler just for it to not work reliably.

A high quality boiler will cost you more but then, the less money you will have to shell out on expensive repairs further down the line.

According to “which?”, the average cost of a boiler repair is £210 which is quite an incentive to pick a reliable brand, especially when you consider these repairs over the boilers life which should be minimum of 10yrs.

To choose the most reliable brand of boiler, you need pick from well established companies with long warranties, The top 4 are:
Baxi, Vaillant and Viessmann, Worcester Bosch.

“QGE and the team have been absolutely fantastic. We had some complicated plumbing work done at our house ranging from external drainage through to internal heating reconfiguration. The communication was excellent throughout, they turned up exactly when they said they would, used carpet protectors and cleaned up afterwards. QGE even responded to an issue on a Sunday night. Unreservedly recommend.”
new boiler installation old street

TIP 2: It’s down to the materials

Many manufactures use different materials for boiler to be cost effective and to produce the best heat efficiency numbers on paper.
Good idea right? ………. not really!

The majority of manufactures use Aluminium for the construction of the main heat source in the boiler, it’s light weight and cheap to make, but the problem is condensation.

All new boilers have to be a condensing boiler, meaning the boiler takes unused heat for the exhaust gases and uses them to preheat the radiator water before going over the gas burner and become hot again. The byproduct of this is water.


One of several problems is that condensation water is slightly acidic and will slowly destroy aluminium, reducing your boilers efficiency year on year and reduce the boilers life span.

Ideally, the best material for your boiler is Stainless Steel.
In short, stainless steel is resistant to the condensate and is also better for the water condition inside your heat system.

It’s imperative you ask you installer if they know about the mismatch between aluminium and condensate.

Condensate PH 4-6
Aluminium Ph range 6-8.3

There are only a handful of manufactures that use stainless steel and they are :

• Baxi*
• Vaillant*
• Viessmann

So here we have narrowed down the manufactures you should only be looking at for longevity.

* only certain model have Stainless steel heat exchangers.

TIP 3: Maximise boiler efficiency with controls

If you are replacing an old boiler chances are your thermostat is old and works on old technology. New boilers are made to run at low temperature and for a long time.

Your old dial thermostat on the wall gives only an on or off command , meaning the boiler will go to maximum every time until the house gets too hot and then switch off until its too cold and then come on.

Using new smart thermostats such as Nest, Honeywell T6, Tado and Vaillant controls make all the difference.

These thermostats speak computer language to the boiler and tell it exactly how much energy to put into your home. Resulting in savings on gas, making your home comfortable constantly and reducing the stress on your boiler which contributes to an extended lifespan.

When selecting your smart thermostat you need check it speak opentherm or more commonly “OT”, which is a computer language.
Vaillant has its own language called eBUS which Tado also uses. For simplicity these two languages are effectively do the same thing, which is talk to your boiler and give it intelligent information.

There are thermostats on the market such as Hive which are not “OT” and are simply a standard thermostat with the convenience of operation form your phone, its important you check for opentherm compatibility.

TIP 4: What size boiler do I need?


When it comes to boiler size, bigger is not better, you need to consider the following:

• Hot water requirements of the occupants

• The heating load of the building

• Will fit in the space you have allocated for it?.

Your heating engineer will have to carry out a calculation of the heat loss of your home and each building is different.

This process requires the room measurements of each room including, how many windows and the type of construction of the building. This calculation will tell the engineer what the Kilowatt rating of the home is and can then select the right appliance for you unique situation.

Installing a boiler that is too big into a property will cause it to cycle on and off continually as it can not get rid of the excess heat. This causes thermal stress to the boiler and can damage the major components causing a premature failure.

Many engineers just select what-ever kilowatt rating boiler was there before or bigger , this is not helpful, so ensure your installer carries out the heat loss calculation and shows you the results.

Now you are armed with this important information, you can now make the right choice for your new boiler and if your installer doesn’t know or care about these things, then you need to find another installer that does.

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