What is a Heat only boiler?

Heat only boilers, also known as conventional or regular boilers, provide central heating to our homes and are installed in many UK properties built before the 1970s. Despite being common household appliances, the workings of these boilers remain a bit of a mystery for many of us.

At Ideal Heating, we believe in making the complex simple. If your heating system has a cylinder and a pair of water tanks, most likely up in the loft, you have a Heat only boiler. These pieces work together to provide all the hot water your home’s radiators, taps, and showers need. In this guide, we’ll explore how they work, their key benefits, and whether they are the right choice for your lifestyle.

Browse all Heat only boilers today.

How does a Heat only boiler work?

Heat only boiler models keep our homes warm and provide the hot water we need for our kitchens and bathrooms. Depending on whether you have an open-vented system or sealed system (see below), your Heat only boiler will work hand in hand with several extra pieces of equipment:

• A hot water cylinder 

• A cold-water storage tank

• A feed and expansion tank

• A pump

The cold water tank is filled from the mains supply, which in turns feeds into the hot water cylinder. That’s where the water is warmed up by a heat exchanger inside your boiler, before it’s then used to supply your radiators, taps and showers with hot water.

A pump is used to send all of the hot water that’s produced through your central heating system, supplying your home’s radiators as well as any taps and showerheads.

Sealed and open-vented Heat only boilers

If you have an open-vented system, a feed and expansion tank will make sure the system’s water levels remain at the same level. It ensures any water lost through evaporation or leaking is replaced, as well as making sure that water expansion caused by heating doesn’t lead to a build-up of pressure.

A sealed system uses an expansion vessel rather than a feed and expansion tank. This might be built into the boiler or be a separate containment unit, and provides space to house water as it expands when the system is heating up.

Learn more about high-efficiency condensing boiler technology.

What are the benefits of a Heat only boiler?

If your home has a high demand for hot water, a Heat only boiler could be the right logical solution. They can supply large amounts of hot water to multiple taps simultaneously, whereas another model might struggle to keep up.

We speak with the assurance that comes from over 100 years of manufacturing. An additional positive is that because they use a pump, they aren't as reliant on mains pressure. If your area has low water pressure, a Heat only boiler will still work properly.

Wanting to get a Heat only boiler, but not sure which size? Try our power calculator.

What size property is a Heat only boiler best for?

Heat only boilers are best suited to large homes where a steady supply of hot water may be needed at the same time, such as a property with two bathrooms where several people all need to wash and shower in the morning.

If you have plenty of space to house your boiler, most likely in your loft, then a Heat only boiler would be a great option. For an example of a modern, hard-wearing Heat only boiler, take a look at the specs of the Ideal Logic+ Heat to see if it could be the right fit for your home.

Are there any drawbacks to a Heat only boiler?

A key point to be aware of when it comes to Heat only boilers is that they can run out of hot water, because they draw water from a cylinder rather than directly from the mains. Once all of the water from the cylinder has been used, it will need to be refilled with cold water and heated to the temperature needed for our hot water taps and showerheads.

Another thing to consider is that if you don’t actually use a lot of hot water, a Heat only boiler may not be the most efficient heating solution. The cylinder may heat up more water than you require to use, whereas a Combi boiler will only provide the amount of water you need.

How to maintain your boiler

Our commitment to quality ensures our products are built to last. We always recommend that your boiler be serviced at least once a year. This ensures your boiler works safely and efficiently while protecting your warranty.

Book an annual service for your Ideal boiler.

Should I replace my Heat only boiler with a Combi?

If your home has three bedrooms or less, one bathroom and one shower, it’s possible that a Combi boiler could be a better option for you. Because it only uses the hot water you need rather than maintaining a constant supply, a Combi would make a more efficient choice.

However, if you live in an older home with less modern radiators, they may not be equipped to cope with the high water pressure supplied by a Combi or System boiler. To learn more about the benefits and drawbacks of Combi boilers and System boilers take a look at our pages: What is a combi boiler? and what is a system boiler?.

Compare Combi vs. Heat only boilers in our guide to replacing an old boiler

Reliability you can trust with Ideal Heating

Whether you are sticking with a traditional setup or looking toward the future, Ideal Heating provides the expertise to ensure you have made the right choice for your home.

Explore the full Ideal Heating Boiler range. 

If you need further advice, use our boiler selector tool or reach out to a trusted local installer to move forward with peace of mind.