How Much Does a Commercial Boiler Cost to Replace

It is difficult to put a price to replacing a boiler as there are so many variables at play. However, in this article I hope to give you some idea of what these are and how it differs.


In one sense buying a commercial boiler is not dissimilar to buying a vehicle. The larger and more powerful the boiler is then the more it is going to cost. When looking to replace a boiler the first factor to look at is going to be the kW output. This is how much energy the boiler can produce and it is based on the load of the building it is supplying and will have the largest impact on the final cost of the project. When replacing the boiler, it often makes sense to simply replace like for like based on the output of the existing boiler. However, it is always wise to double check the building loads required as the existing boiler could have been over or undersized for a number of reasons.


The second point although seemingly obvious is how many boilers you are replacing. It is usually cheaper to go for one larger boiler however many commercial properties have two or more so that should one of the boilers breakdown for any reason they are not left completely without heating or hot water until the boiler is fixed and back up and running. When doing this it is common practise to have slightly more capacity than you need so that the remaining boiler or boilers will still be able to reach a comfortable temperature on their own. An important point to note here is that by having more than one boiler and more kW’s than you need your boiler should last longer than were you to choose a single boiler with only just enough power. This is because the boilers will not have to work so long and hard to keep the building up to the desired temperature.


The third main factor is the location of the boiler and the space available. Floor standing boilers tend to be more expensive than wall mounted until you get to around 400kW mark where you would need a lot of wall mounted boilers to make up the output and so it would be cheaper to install fewer large floor standing boilers.  However, in some plant rooms particularly basement pant rooms, there is simply not the space or height to fit wall mounted and so floor standing boilers would have to be installed. The location is also very important as the flue run can make a substantial difference to the cost of the boiler. Occasionally a flue dilution system may have to be installed if the flue can’t be installed 2 meters above ground level or is too near an openable window.  This is best avoided however as they don’t work that well with modern condensing boilers.


Control systems can make the largest difference to a boiler change. for example in a house or church where there is little need for sophisticated controls you can simply use the boiler controls with a simple time clock. However in other situations a full BMS control system may be required. This can in many cases cost more in its own right than the boiler works depending on the size of the project and the requirements. Other times its not even necessary to change the controls and the existing control system can be connected onto.


Then there is other associated equipment that may accompany the boiler change. This is not always necessary but for example if your pumps are very old and may not have much life in them then it may be cheaper to get them replaced with the boiler whilst your doing the works rather than wait till they fail and have to then get someone out to replace them at a later date. Sometimes it is recommended particularly on systems whether there is old pipework then it is recommended that a plate heat exchanger be installed to separate the boiler from the system. This can add to the cost quite dramatically as they can be expensive items of equipment and it will also mean further pipework alteration and additional pumps in the plant room. However, it does provide protection for the boiler and can prevent irreparable damage to the boiler that could mean having to replace it or at least change the heat exchanger in the boiler itself after sometimes only a few months if there is a lot of debris in the system.

These are the main variables however as you can imagine there are many other things that could significantly vary the cost for example if there is any asbestos in the plant room, roof repairs if you are using a new flue route, chimney alterations and many other potential complications.

So overall there are a lot of variables that will affect the price you pay for replacing a commercial boiler which is why when you get a price you will find that the contractor will always want to survey the site first so that there are no unexpected costs even if it is a seemingly straightforward change. This said if, for a very straightforward single boiler replacement a guide you can use to give you a rough idea before you get firm quotations is to be thinking somewhere between £100 – £150 per kW. So, for example, to install a new 80 kW boiler you would be looking between £7,200 and £12,000. However as soon as you have complications like a long flue run, new controls, having to replace pipework, installing a secondary heat exchanger then this can change the final price substantially.

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