If you have a home that is not connected to the mains gas grid you will probably be one of the 1.5 million homes in the UK that use oil heating.
If so, selecting the wrong oil boiler for your home could cost you thousands of pounds in wasted energy bills and repair costs.
One of the biggest mistakes people make…
is going out and buying an oil boiler without fully understanding what they need.
Which means they end up with a boiler that is too small, too large or just the wrong type for their home.
And that is an expensive mistake to make.
In this guide we’ll tell you…
- Oil boiler types explained
- Oil boiler sizing explained
- Oil boiler installation considerations
- How to future proof your oil boiler
So whether you are a homeowner trying to find a reliable oil boiler for your home or a landlord looking for the most cost effective heating system, our expert guide will tell you exactly what you need to know.
Ready to learn more? Read on.
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- Are oil boilers still worth it for off-grid homes?
- Oil boiler types explained: picking the best type for your home
- Oil boiler sizing explained: don’t make this common mistake
- Oil boiler efficiency explained: the ratings that matter
- Oil boiler installation considerations: take note
- Maintenance: how to make your oil boiler last longer
- Wrapping up
Are oil boilers still worth it for off-grid homes?
If you live in a rural off-grid property then you have no choice but to use an oil boiler for your home heating.
Oil boilers are the best option for homes off the mains gas grid as they provide a reliable, long-lasting heating solution for both radiators and hot water.
How do oil boilers work?
Oil boilers work by burning kerosene that is stored in an external tank. This heats water which is then pumped around your radiators or out through your taps.
Simple but effective heating technology.
And one that is tried and tested.
The key thing to note when considering oil boiler installation is knowing the cost of an oil boiler replacement beforehand.
This will give you a good idea of your budget so you can narrow down the models on the market that suit your needs.
The boiler unit itself will cost you between £1,800 and £4,000 on average.
But that’s just the start.
You also need to factor in the installation labour costs, any expenses associated with removing your old boiler and the cost of upgrading your system.
The result is an investment of between £3,000 and £7,500 or more depending on your property.
It’s the reason getting your oil boiler right the first time matters so much.
The good news is modern oil boilers are as efficient as it gets.
The best models achieve efficiency ratings of up to 97.4%.
This means that nearly all of the fuel you purchase is converted into usable heat to keep your home cosy.
Oil boiler types explained: picking the best type for your home
The three main oil boiler types are regular, system and combi boilers.
And they each suit different homes and heating requirements.
Regular boilers work with a separate hot water cylinder and cold water tank.
This system is great for larger homes with multiple bathrooms that require a lot of hot water simultaneously.
The downside is they take up more space.
System boilers are similar to regular boilers but don’t require a cold water tank in the loft.
This makes them more compact and easier to install in properties with limited space but high hot water demand.
Combi boilers heat water on demand straight from the mains.
No tanks, no cylinders, just instant hot water wherever you need it.
Combi oil boilers are great for smaller homes but can run into problems if multiple taps are on at once.
All modern oil boilers are condensing boilers.
Condensing boilers extract heat from exhaust gases that older boilers simply wasted.
This is how they get such high-efficiency ratings.
Oil boiler sizing explained: don’t make this common mistake
Most people get it wrong here.
Assuming bigger is always better when it comes to boiler output.
The truth is an oversized boiler will be constantly turning on and off wasting fuel and wearing out components more quickly.
An undersized boiler will struggle to keep your home warm enough.
Boiler size is measured in kilowatts (kW) and the right output depends on your home size, insulation levels, number of radiators, hot water demand and other factors.
These are the rough guidelines…
- Small homes with 1-2 bedrooms need 18-26kW boilers
- Medium size homes with 3 bedrooms require 26-35kW output
- Large homes with 4+ bedrooms need 35kW or more
Don’t just guess at your boiler size though.
A qualified installer can do a heat loss calculation that will work out the exact kW output you need based on your home’s specific characteristics.
This will ensure you get the perfect size boiler.
Oil boiler efficiency explained: the ratings that matter
Oil boilers have to meet minimum efficiency standards, but not all boilers are created equal.
A few key numbers to look for when comparing oil boiler models…
SEDBUK rating: The % of fuel that is converted into usable heat. Efficiency ratings of 90% or above are considered efficient but the best boilers achieve 94-97% efficiency.
ErP rating: Letter grade from A+++ to G showing how energy efficient the boiler is. Always aim for A or above rated boilers at a minimum.
One thing to note…
According to recent data, running an oil boiler for an average UK home will cost between £1,200 and £2,000 each year depending on the size of the property and insulation.
This means that a highly efficient boiler can save you hundreds of pounds per year over an older lower efficiency model.
This efficiency gap will add up quickly over the boiler’s expected lifespan.
Oil boiler installation considerations: take note
Installing an oil boiler isn’t a DIY job.
You must use an OFTEC-registered engineer to install your system legally and safely. Using a non-registered installer voids warranties and is dangerous.
Your oil tank must meet current regulations. It must be bunded (double-skinned) if it holds more than 2,500 litres of oil or is within 10 metres of a watercourse.
Flue positioning is important for safety reasons. Exhaust gases must discharge away from windows, doors and air intakes.
System upgrades may be needed depending on your existing set up. Installing new pipes, radiators or controls could be required to get the best performance.
Which is why choosing a fully qualified installer is vital.
Maintenance: how to make your oil boiler last longer
You can make your oil boiler last 20+ years instead of just 10-15 if you do regular maintenance.
Annual servicing by an OFTEC registered engineer will keep your boiler running efficiently and catch small issues before they become big, expensive repairs.
Between servicing do these checks…
- Keep an eye on your oil level and order refills when you start to run low.
- Check for leaks around the boiler and tank.
- Listen for any unusual noises when the boiler is running.
Treat your oil boiler to regular maintenance and it will reward you with fewer emergency breakdowns in the depths of winter.
Wrapping up
So that’s our oil boiler buying guide.
Choosing the right oil boiler comes down to understanding your home’s heating needs and property characteristics.
Get the sizing right, choose an efficient boiler and work with qualified installers.
Proper maintenance will also help your oil boiler run strong for decades.
Your investment upfront will pay for itself in lower running costs and reduced repair bills.
Modern boilers are also compatible with HVO, a renewable fuel which can cut emissions by up to 88% as it becomes more widely available.
Make sure you take the time to compare different models and get quotes from OFTEC-registered engineers.
Quality not price will be the deciding factor so don’t cut corners on your oil boiler.
Your future self will thank you when your home stays warm and your heating bills stay under control.
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