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Step-by-Step Boiler Sizing Guide

At Origin Plumbing and Heating, we understand that choosing and sizing your boiler can be complicated. When working out what size boiler you will need, the first thing to consider is,how much heat and hot water do you and your family require. This will help you to determine the correct boiler size and minimise the stress of the boiler installation process. It is important to choose your system size correctly so that you can have hot water at your disposal and heat your home efficiently. This will also avoid creating high energy costs. Here at Origin our engineers are highly trained and well experienced in all aspects of boiler installation and repairs.

Boiler size also affects what type of system you will need.

Combi Boilers

Combi boilers, short for combination boilers, are one of the most common boilers installed throughout UK homes. This type of system will fulfil both your heating and hot water demands. The size of your combi boiler will be determined by your family size, demand for hot water and the amount of bathrooms in your home. The correct sizing is crucial with this type of system. However, when sized and installed correctly they are practical, versatile systems. Other benefits of the combi boiler include being efficient, easy to maintain and low cost to run.

Combi Boiler Size Calculator

Before looking at the factors which decide the size boiler you will need, understanding how boiler size is measured first is key. You need the output of the boiler in kilowatts (kW) and not the physical dimensions of the boiler. A kilowatt unit is used to measure how much energy is emitted from a boiler in heat. The more hot water and heat your home requires, the higher the boiler output will need to be. These three factors will determine what size boiler you will need: 

  • The number of radiators
  • The number of bathrooms (with non-electric showers)
  • The number of people in the home (the demand for hot water)

combi boilers

It’s always best to book a consultation with a gas engineer to size and install your boiler. This will ensure you have the correct system for your needs and that it has been installed correctly. Visit our website to find out what boiler models and sizes we offer. Contact us today to book a consultation.

Gas Boilers 

Installing a gas boiler can be a little more complicated. Using natural or propane gasses, gas boilers heat the water in the boiler to boiling point. Once the steam is created, it is then transferred using the pipes in your system to the individual radiators throughout your home. A gas boiler that is too small for your home will not fulfill your needs. It will struggle to cope with demand and therefore will not provide hot water and heat efficiently. Installing a gas boiler that is too big, will leave you with more than you require and expensive energy bills. When it comes to sizing this kind of system, the process is a little more technical and will involve calculating the square feet in your home.

Gas boiler size calculator 

To calculate a gas boiler, you’ll need the size of your house to hand. You were likely informed of this when you brought your home, however, if you do not have this information, you’ll need to measure your home. To begin, measure each of your rooms by beginning in the corner. Measure the two walls that meet in this spot and then record the dimensions. Complete this step for each room, once you’ve finished you’ll need to convert all of your measurements into square feet. The next step is to calculate the BTU’s (British Thermal Units). 

gas boilers

Your boiler system will need to produce 50BTU per square feet of your home to heat it efficiently. To get a rough size estimate multiply the measurement of your home by 50. Other factors can affect boiler size and therefore, it can become complicated. Variables such as heat loss and boiler installation can affect the amount of work your boiler needs to do. To ensure you have the best sized system for your home, it’s best to contact a reputable engineer.

Need Advice Now? Check Out Our Video Plumber Service!

At Origin, we can offer you instant quotes using online video calling! Our team members take a look at the problem using a popular video chat program, including Facetime, Whatsapp, or Zoom to evaluate the problem, determine the cause, and then let you know what needs to be done. This allows us to get you the information you need quicker and more conveniently than ever before!

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