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Last updated: 18th August, 2023


Heat Only Boilers

Heat Only Boilers

Buying a new boiler can be a stressful process. There are a lot of different systems to consider, from water supply to fume exhaust vents.

Buying a new boiler can be a stressful process. There are a lot of different systems to consider, from water supply to fume exhaust vents. You'll want to make sure you know what you're doing before you checkout your shopping basket.

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We're here to help you wrap your head around the world of Heat Only boilers and how to install them in your properties, from how much a heat only boiler type will cost you to regular delivery and VAT options to supply your heating radiators properly.

If you've got any more questions after the end of this guide, feel free to connect with us, and our customer service team will be happy to help you with boilers or replacing heating in your property.

What is a Heat Only Boiler?

Heat only boilers are often also known as regular boilers, open vent, or conventional boilers, as opposed to combi boilers, which are more complex and run your heating and hot water together.

Heat only (or regular) boilers provide the heat that is used in your central heating system range, and hot water stored in large cylindrical water tanks rather than share heating and hot water. This type of boiler is more commonly found in larger properties.

Heat only boilers are for heating a house, which means that they often require a lot of external accessories. The efficiency levels of a classic open vent system boiler are better, though.

If you're in the search for something to replace a regular boiler, don't feel you have to search for the best combi boiler. With the right support and warranty, a heat only boiler can be a great, efficient option at an affordable price.

Do I Have A Heat Only Boiler or a Combi Boiler

All boilers heat water. That's just what they do. But when you're staring into the cupboard and trying to work out what sort of boiler is heating your house, it can be difficult to work out the answer.

You can't just use the brand to tell, either, as many of the leading brands such as Potterton, Worcester, Vaillant, Baxi and Glow-worm all deliver both combi boilers and heat only boilers. There are a few details you can use to identify a conventional boiler, however.

In general, a modern combi boiler will combine all of the elements of a heating system into a single device. A classic heat only model comes with vat and water pressure attachments that are used for providing central heating water. Search for these to identify what type of system you have.

An efficient heat only boiler will be installed alongside multiple separate hot water storage cylinder vat, cold water storage tank vat, and feed and expansion tank units for support.

The last of these is usually kept in the attic above the boiler somewhere to allow gravity to help out with the water pressure and help with efficiency in your boilers heat system.

Look out for cold water tank units and hot water cylinder tanks in the loft! You're also likely to have a separate external circulating pump component rather than one held within the body of the boiler itself.

All of these peripheral elements are indicators that you might be dealing with a classic heat only boiler.

Different Types of Heat Only Boiler

Heat only boilers are a broad category and one which includes a wide range of multiple different models, styles, and designs. This means that there are types of heat only boiler output suited to different sizes of homes and different budgets, even from big brands like Glow-worm or Worcester.

The biggest difference between different heat only models is in size. If you've only got a small home, then a smaller hot water device will be fine.

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How much does a Heat Only Boiler Cost?

The cost of a heat only boiler can vary. The gap between large and small models can be a major difference with VAT taken into account, even within a single brand such as Glow-worm.

When buying appliances, additional VAT charges can add up, so keep an eye on VAT as you plan your budget. Make sure you include that extra 20% for VAT, as VAT is not always clear on listings.

No matter what you're buying, VAT matters, an unwanted VAT charge can ruin your budget!

A low-end regular option will come to around £400 to £500 in your basket, VAT included, while larger regular models will be more like £1600, VAT included, from leading brands like Glow-worm.

Consider your budget and make sure you take VAT into account before you add a hot water boiler to your basket because VAT can be a nasty surprise, but there should be something that is easy to deliver to you. The VAT registration is the same for both types, so no need to worry about VAT after you've included it.

It can cost additional money to deliver your tanks to your home, but it should be possible to find a boiler delivery system that will deliver them for free. The team that deliver your boiler should also be able to install it for you as well as deliver it.

Installing a Heat Only Boiler and Hot Water Cylinder

Heat only boilers can be quick to install if you already have the additional water tanks and filter basket installed. In this case, you can have a small sealed hot water boiler unit installed in a cupboard in your kitchen.

If you don't have the water cylinders already installed in your home, then installing an open vent model is going to be harder and come at a higher price. You'll need water tanks for your home, which will usually be placed in your loft. That can take a lot of time and effort and can be more expensive.

Hire professional plumbers or installers to install your regular boiler for you. Most boiler retailers will be able to help with that! Add services such as that to your basket.

You should be able to get free delivery as part of the installation. The delivery team and installers will be able to help you with gas and flue setup, delivery, vat filter installation, and free output management.

Best Heat Only (Regular) Boiler Brands

At iHeat we have a great range of Heat Only boilers available in a range of kW's suitable for your home.

Worcester Heat Only / Regular Boilers




Worcester Bosch Ri 15kW



Worcester Bosch Ri 18kW



Worcester Bosch Ri 21kW



Worcester Bosch Ri 24kW



Worcester Bosch Ri 27kW



Worcester Bosch Ri 30kW



Viessmann Heat Only / Regular Boilers




Viessmann 100-W 16kW



Viessmann 100-W 26kW



Viessmann 100-W 35kW



Ideal Heat Only / Regular Boilers




Ideal Logic+ 15kW



Ideal Logic+ 18kW



Ideal Logic+ 24kW



Ideal Logic+ 30kW



Boiler Support and Repairs

Repairing a classic style heat only boiler is complex. You should be able to get a few years warranty and breakdown cover from your chosen boiler retailer, and calling in a professional for repair work should be straightforward. Call customer service if you're not sure what to do.

When you check out your basket for your regular boiler, make sure you add warranty to your basket. Even the best boiler goes wrong sometimes, and adding VAT, warranty etc. to your basket can make your life as a customer much easier in future without needing to deliver additional products for flue, gas, or output maintenance!

Should You Go For A Heat Only Boiler?

Regular heat only boilers might not be quite as convenient as combi boilers, but they are much more affordable and nowhere near as complex as you might expect.

Choosing a boiler for your home is an important decision, so you should take it slowly and carefully and consider delivery options. Consider the size of your home and what sort of infrastructure you already have built into your home, and plan your heating system to match those variables!

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Stephen Day profile photo
Article by
Stephen Day | Co-founder
Gas Safe registered and FGAS certified engineer with over 20 years experience in the heating and cooling industry.