New Boiler Installation Guide

How to make sure you get a good boiler installation

When it comes to getting a new boiler it can by necessity have to be a quick decision.  This is usually because you have found yourself with broken boiler and need to get your heating and hot water back up and running as soon as possible.

We understand that when buying a new boiler and having it fitted can feel like a lot of big decisions that you need to make.

Please read our blog below to get a view on the information exchange you should have with your engineer.  This will make the process easier for you.

Our guide on types of boiler, so you can understand the right type for you:

  • Combination boiler / combi boiler: This is the most frequently used type of boiler. It provides on demand hot water and can be good choice for many people’s residences.  However, it should be noted it is not the best choice for everyone. There are situations where heat-only or system boilers are a better option.
    • Positives of Combination boilers: The boiler is compact in nature as it houses neatly all the component parts within its own case.  This not only gives a neat appearance but also removes the need for a cold-water supply and expansion tank in the loft space.  Most importantly this type of boiler can provide hot water as demanded.
    • Negatives of combi boilers: Due to the number of moving parts in this form of boiler there is an increased potential for issues in comparison to a conventional boiler. The combination boiler option is most appropriate to a property with a smaller number of inhabitants.  This is because you can only us the hot water from the boiler for one purpose at a time.  An example of this would be whilst one person is running hot water in the kitchen another cannot use hot water in the bathroom to have a shower.
  • Heat Only / Conventional boilers: This type of boiler is heat only and needs a water tank with components like the circulation pump being located external to the boiler. This type of boiler usually requires cold water plus expansion and feed tanks that are located in a loft space.  The generated hot water is held in the hot water cylinder/storage tank.  This approach will usually have an on/off switch allowing you to create a reservoir of hot water for when you know you are going to want it.  You also have the option to have it switched off when it is not needed.
    • Positives of Heat only boilers: These types of boiler are more appropriate to homes that have a need to provide hot water to a number of occupants at the same point in time.
    • Negatives of heat-only boilers: These types of boilers will not provide on demand hot water. This means there is a waiting period for hot water once the storage tank becomes empty.  An example of this could be if a resident has just run a bath.  Due to the nature of these boilers not being on demand and the slow loss of heat from the hot water storage tank they are less efficient than combination boilers.
  • System boilers / closed vent boilers These can be a good option if you feel your requirements suite a heat-only boiler type, but you don’t like the idea of a lot of external components to the boiler. In this type of boiler, a number of parts that are external in a heat-only boiler are contained withing the boilers body.  It should be noted that this boiler approach still needs a hot water cylinder.  However, the feed and expansion tank that is normally placed in the loft space is covered by an expansion vessel within the boiler.  The boiler will typically also house the pump and a number of the valves.
    • Positives of system boilers These are suited to large homes where you want to have hot water available at multiple taps simultaneously. This approach does not require a large cold-water tank housed in a loft space.  This is a very good for if your residence is in a location with low water pressure from the mains.
    • Negatives of system boilers This approach requires you to be able to situate a hot water cylinder. These types of boiler can be more expensive to install than a basic level combination boiler.  As for conventional heat-only type boilers, system boilers are not as efficient as the combination style of boiler.  This is in part due to their loss of heat from the hot water cylinder over time.  In addition, there is a time lag in waiting for hot water once the heating tank has been emptied.

Installation of the Boiler

When you engage with a heating engineer regarding acquiring a quote to provide you with a new boiler this should not be just a quick chat.  Good engineers take the time necessary to perform a complete heating survey of the residence.  Further the engineer will gain an understanding of the requirements for hot water and heating.  Once this has been done the engineer will be able to give you a recommendation regarding the size and type of the boiler, they feel is most suited to your needs.

Below are a number of questions you should give consideration to prior your conversation with the engineer/installer:

What you need to be aware of for a good boiler installation

Make sure you inform your engineer/installer of the full details of both your hot water and heating requirementsDon’t forget to include any plans you might have for the future of your residence.

Give consideration to the questions detailed below and ensure you pass on the answers to your engineer/installer:

  • What it the nature of your hot water usage. g. Do you frequently require hot water from greater than one tap shower at the same time?
  • What is the shower type you have? Is it a of a pumped power type or do you intend to put in one of this type in the future?
    • If you have or do a combination boiler is not in a lot of cases compatible with a powerfully electric pumped shower. Therefore, if you want to go down the combination boiler route you will need to lose the shower pump facility.
  • How do your requirements for hot water change across the year? g. do you regularly have a number of house guests?
  • Are there any house improvement activities you have planned? An example of this would be if you are intending to extend the property or perform a conversion on your loft space.  You will also want to inform them of works such as under floor heating or the installation of an additional bathroom.
  • What have been the problems with your current system? Give yourself a good amount of time to think back on issues you have had.

The answers to the above questions will be of large importance for the engineer/installer to recommend the correct type/size of the boiler for your residence.

Questions to put to the engineer/installer so you get the best installation

During your conversation with the engineer/installer about your needs for hot water they are likely to raise some if not all of the following for your consideration.

Your engineer/installer will be able to provide you with a good understanding of the positives of each extra option.  It should be noted not all of the extras will be necessary for many installations.

The benefits of each will need to be balanced against the expense.  It should be noted however that extras like system flush or water filter are likely to be helpful towards the health and longevity of the systems working life.


  • Condensate disposal This covers pipework that routes water produced from boiler to a drain. Any external pipework should be minimized.  If any of this pipework requires it to be external to the property it should be protected from cold temperatures.
  • Water treatment (flushing and cleansing) The majority of heating systems will need at a minimum a gravity flush and cleanse plus a chemical inhibitor on the final system fill. Systems that are heavily sludged may be in need of a powerflush.  Your engineer/installer will be able to advise on the best option and the reasons for it.
  • Scale reducers / system filters Enquire of your engineer/installer if these are appropriate as they can potentially increase the life of the boiler. It should be noted that Scale reducers are important for hard water areas where a combination boiler is installed. 
  • Plume effect (water vapor generated from the boiler flue) The size of the plume that is likely to happen? and will where it is to be placed? Will this cause concern to your neighbors because of its location?  It should be noted that the plume can be taken further away using piping called a plume management kit.
  • Controls for the heating Do you have the heating controls you require? Plus what other choices are available to you?
  • Radiators Do you have older radiators? These can be inefficient or be corroded internally.  If this is the case, they might need to be replaced.  Ask for advice from your engineer/installer.
  • Additional energy-saving measures There is government legislation the requires the installation of a new boiler to have as a minimum one of the following four energy-saving measures: Smart heating controls, Weather compensating thermostat, Load-compensating thermostat, Flu gas heat recovery.

Your engineer will be able to take you through the positives and negatives of each and provide guidance on what it suitable for your residence. Contact us today.

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