Boiler Installation Dartford Kent

Boiler Systems: What Are The Different Types of Boiler Systems?

Boiler Systems: What Are The Different Types of Boiler Systems?

Do you need to replace your boiler? A lot of customers that I talk to confuse themselves by researching the different types of boiler systems that are available. I often get asked “how do boiler systems work?” and “which boiler system is best suited for my house?”

One of the problems with having access to so much information out there via the Internet is that, unless you know where to look, you often waste hours reading irrelevant material which is probably of no use. If you have a three bedroom semi detached house it’s unlikely that you’ll need a GRP water tank, multiple unvented cylinders and a Grundfos CME Booster pump to handle your heating and hot water needs.


I like to compare it to researching personal health symptoms on Google and concluding that you have a terminal disease when you probably only have a sore throat!

Some things are best left to the experts and choosing the right boiler system for your home is best left to an experienced, qualified Gas Safe Registered plumber.

For the majority of households in the UK you’ll only need to concern yourself with either a combi boiler system or a system boiler system. A small percentage of homes may benefit from a conventional open vent boiler system so I’ll explain all three.

Worcester Gas Combi Diagram

How a combi boiler system works

Combi Boiler System

A combi boiler system, or combination boiler system, is the most popular type of boiler in the UK. It’s a water heater and central heating boiler in one – hence the name.

They’re very popular because homes in the UK are typically small and tight for space. With a combi boiler, you don’t need any tanks or cylinders so it’s normally the best option to go for.

They are cost effective and energy efficient as water is heated on demand rather than stored in a cylinder full of hot water.

The water is delivered at mains pressure so if you live in an area with good water pressure then you’ll have a great powerful shower like the ones you get in posh hotels!

If you have low mains pressure do not despair as there are way around this. I won’t go into detail but feel free to get in touch with us so that we can advise you accordingly.

So to summarise the advantages are:

  • Unlimited hot water on demand
  • Space saving as there is no need for anything else
  • Quick to install so you save on labour costs

A disadvantage that I must mention is if you live in a household which has more than one bathroom. If both showers are used at the same time then the water pressure will drop as the water supply is literally split in half. If someone turns the kitchen tap on then it’s split into three. A minor disadvantage if you manage shower times accordingly but important to mention so that you consider all aspects.

Worcester Gas System Diagram

How a system boiler system works

System Boiler System

A system boiler requires an unvented cylinder (for best results) for storing hot water and heats your central heating system directly.

There is no need for anything extra in terms of cold water or expansion tanks in the loft as the heating and hot water components are built into the actual boiler itself. This makes it pretty reasonable in terms of the amount of space that you need when compared to the benefits that it offers.

One of my favourite features of this system is that if two or more showers are being used at the same time the water pressure doesn’t drop by much. Everyone will still have a great shower.

If you live in an area with high water mains pressure, when using an unvented cylinder, this pressure is maintained throughout the system so you have a strong flow of water coming through your taps and showers.

If you don’t have good water pressure than contact us for alternative options. There’s always a way around this issue.

To summarise:

  • Perfect for homes with more than one bathroom
  • Constant supply of hot water to all taps and showers
  • Economical to run
  • Installation is relatively quick which makes labour costs reasonable

Larger homes may benefit from a circulation pump so that the hot water comes out instantly as soon as you open the tap.

I can’t think of many disadvantages to this system except for the higher initial costs, to begin with in terms of equipment but the benefits easily outweigh this issue. This is probably my favourite system for homes with two or more bathrooms.

Worcester Gas Regular Heat only Traditional Diagram

How a conventional open vent boiler system works

Conventional Open Vent Boiler System

A conventional open vent system, or traditional, regular or heat only boiler system, is a boiler, expansion tank, cold water tank, and hot water cylinder set up. The boiler sends hot water to your radiators, the expansion tank maintains the water level in the central heating system, the cold water tank feeds the hot water cylinder which sends hot water to your taps and showers.

It sounds very complicated I know but it really is simple. It’s a traditional method which has stood the test of time but newer systems are making this one obsolete.

A great feature of this system is that the water pressure is maintained even when multiple taps and showers are open as water is fed from a reservoir as opposed to a small 15mm pipe.

To summarise:

  • Great for houses with more than one bathroom
  • Suitable for areas with low mains water pressure
  • You need a lot of space
  • You’ll probably need a separate shower pump
  • Installation takes longer so higher labour costs
  • Once the cylinder runs out of hot water you need to wait for it to refill and then heat up

A final note on having a hot water cylinder is that it is usually fitted with an electric immersion heater so if your boiler develops a fault then you switch to using the immersions as a temporary backup so that you still have hot water. No more cold showers!

Boiler Installers Dartford Kent

We install boilers in South East London & Kent

Which Boiler System if Right For Me?

Use this information as a guideline only but like I mentioned in the beginning of this blog, always consult an experienced, qualified Gas Safe Registered plumber to help you choose the right boiler system for your home. It is not as simple as it sounds so leave it to us professionals!

If you liked this blog post and found it useful I’d be grateful if you could help by sharing it with your friends and family on Twitter or Facebook.

If you have any questions feel to free to comment down below and I’ll answer them personally.

If you live in South East London or Kent and need some advice in terms of what boiler system to choose for your home then feel free to get in touch. We’d love to hear from you.

We install boilers in all areas around South East London and KentCall us for a free quote!

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Richard Costello, from Dartford in Kent, is the owner of MultiPlumb and has been involved in the plumbing industry installing bathrooms and boiler systems for over 15 years. If you have any questions or suggestions for future blog posts feel to get in touch at richard@multiplumb.co.uk.
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