System Boilers

System Boilers Matty July 7, 2022
Vokera Vision Plus boiler in kitchen
system boiler cutout

What does a system boiler do?

System boilers fit somewhere in between a combi boiler and a regular boiler. A system boiler has a separate hot water storage cylinder but doesn’t require a cold water storage tank.

System boilers are ideal for homes with high hot water demand, usually due to requiring hot water in multiple bathrooms at the same time.

System Boilers

A system boiler is a boiler type, like a combination boiler or a regular boiler, that is more commonly found in larger homes with a higher demand for heating and hot water.

System boilers have a separate hot water storage tank which allows a system boiler to store hot water so that it’s ready on demand. If you aren’t sure what boiler type you have, we’ve written a blog covering it to help you out.

Due to a system boiler storing hot water, it means that they are able to provide a constant supply of hot water to multiple outlets in your home at the same time. So if you have two bathrooms with taps and showers running, you will still have hot water in both and the water pressure will not be affected.

Despite combi boilers being the most popular boiler type in the U.K, there is still a place for the system boiler. A system boiler setup comprises the system boiler itself and a hot water storage tank.

As with a combi boiler, a system boiler is connected to the mains water feed, heating water directly as it comes into your property. Once a system boiler heats water via the heat exchanger, it is pumped into the hot water storage tank, so you have a nice amount of hot water ready and waiting.

A combi boiler heats water on demand, when you turn on a hot water tap it will heat the water instantly. Combi boilers do have a small reservoir of hot water stored within the boiler but not the same volume as a system boiler.

A system boiler is a ‘sealed system’, so it can benefit from condensing technology. Condensing boilers recycle energy from the exhaust gases your boiler emits to preheat the cold water, making the system even more energy-efficient.

System boilers are very similar to regular boilers as they both pre-heat water and store it in a separate storage cylinder. 

However, regular boilers require a cold water tank in the attic, rather than taking the cold water directly from the mains as it enters your home. Regular boilers are usually found in older homes, and they are often converted to combi boilers when the time comes to replace your boiler.

Regular boilers are kept under pressure with the use of a header tank in the loft (also called a feed & expansion tank), whereas system boilers use a pressurised heating circuit, topped up by mains water.

Regular boilers use an external expansion vessel to maintain the water pressure, while the expansion vessel is often internal in a system boiler. Regular boilers use more space than a system boiler and often require more complex piping, which is why system boilers are more commonly used in modern properties with multiple bathrooms.

Most homes in the U.K choose to have a combi boiler fitted, you can choose to convert your system or regular boiler to a combi boiler when you complete the WarmZilla online survey to get your boiler quote. It only takes a few minutes and you’ll be given a selection of boilers to suit your home.

Any system boiler purchased from WarmZilla comes with Gas Safe installation, system filter, system cleanse, inhibitor, smart thermostat, up to 12 years guarantee, any flues or extension kits you may need; plus, if your condensate or gas pipes require upgrading – that’s included in your fixed price regular boiler quote too!

You can choose to change your system boiler to a combi boiler or replace your system boiler for another system boiler using the WarmZilla online survey.

You can also add thermostatic radiator valves and radiators to your order – all your heating requirements with one easy online purchase.

What system boiler you need for your home depends on a few factors – how much you want to spend, what brand of boiler you like, the setup of your current boiler, and the size of your home.

System boilers usually run on natural gas, LPG, or oil. Many system boilers are solar compatible but you will need to check for each boiler.

We’ve got a handy blog covering the best system boilers currently available to buy, so if you are looking to replace your system boiler, it’s worth having a read to see what the best system boiler replacement options are.

If you don’t want to do any research on buying a new boiler, the good news is, you don’t have to. Just take the WarmZilla survey, answer a few simple questions about your home and we’ll recommend suitable system boilers from brands you can trust.

If you like to do a bit of boiler research before you buy then you’re in the right place. You can use our boiler comparison tool to compare up to three system boilers against each other in a head-to-head showdown to see which one has the stats you’re looking for.

System boiler prices vary by brand, kW model, what kind of flue you need, whether you need a gas pipe upgrade, and more.

We’ve covered everything you will need to know in our new boiler cost guide blog. Giving you all the info on the costs involved in getting a new system boiler installed and all the extras you get with a WarmZilla boiler.

System boiler prices from WarmZilla start at £1945 for a Worcester Bosch 12i, a very reliable boiler from a very reliable brand. You can also pick up an Ideal Logic 18kW boiler for £1989.

WarmZilla offers the best boiler prices on the market, guaranteed. Or we’ll give you £50 off your order.

The main things that are carried out on a boiler service are;

  1. Visual inspection
  2. Check for corrosion and leaks
  3. Ensure boiler seals are in good condition
  4. Check gas/oil pressure
  5. Test appliance to ensure the rate that the gas/oil is being burned is safe
  6. Combustion analysis 
  7. Ensure correct operation of components and controls

A service certificate is then issued detailing what has been done and any remedial works (if applicable).

Servicing your boiler can also save you money as it could be operating inefficiently – it might only need a few tweaks here and there to correct it and put it back to how it should be. Saving you money on utility bills and potentially expensive repair costs that could have been preventer with an annual boiler service. Who doesn’t link to save money!


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