Installation Cost Guide: Vented & Unvented Hot Water Cylinders

Most homes in the UK have a combination boiler.

But, if you have high demand for hot water, there’s a good chance that water is pre-heated and stored in either a vented or unvented hot water cylinder.

In our 5-minute guide, we’ll cover the two types of cylinder (vented and unvented), typical cylinder installation costs, the best brands and where to find installers.

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Do You Need Vented Or Unvented Cylinder Installation?

There are two types of hot water cylinders:

  • Vented
  • Unvented

The end goal is the same, but there’s a few minor differences.

What Is A Unvented Hot Water Cylinder?

An unvented cylinder is extremely basic. It’s water source is the mains water.

So, an unvented cylinder is the perfect choice if you don’t have space for a water tank, or you’re converting your vented system into an unvented system because you want to save space.

Of course, the downside is if mains water is off for whatever reason, you won’t have hot water (except for what’s left in the tank).

What Is A Vented Hot Water Cylinder?

A vented hot water cylinder is slightly more complex.

It will require a hot water storage tank. If you have a hot water storage tank (most likely, in your loft), you’ll need a vented hot water cylinder.

And, you’ll need to make sure it’s in an area of the house that doesn’t go below freezing in the winter, or you’ll have no hot water at all. That said, a cylinder tank jacket will usually keep water from freezing 99% of the time.

Hot Water Cylinder Installation Costs

We’ve detailed costs below for both unvented and vented cylinder replacement costs.

This assumes that this is a like-for-like swap. Expect to add £250-350 onto the cost of labour if there is not a cylinder already in your property (and therefore, pipework needs to be fitted), or if the cylinder needs to be moved to a new location.

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Unvented Cylinder Replacement

The biggest factor that alters the cost of installation is the type of unvented cylinder you choose.

How big is it?

What brand is it?

If we take Worcester Bosch as an example, they have the SC-90 unvented on offer for around £600. But 90L is extremely small.

But, their SC-300 is over £900 – that’s a huge difference in price.

There are much cheaper options available. Expect to pay anything from £400-1,250 for unvented cylinder installation.

Unvented Cylinder Replacement

The size and brand of the unvented cylinder you choose is going to have a huge bearing on overall cost.

A cylinder could cost anywhere from £500-1000 and costs associated with labour will be £275-450 depending on the ease of the install.

Is A Vented Or Unvented Cylinder Cheaper?

Although it will depend on the specific installation, typically, a vented hot water cylinder installation will cost a lot less than a unvented installation.

When Do You Need A New Hot Water Cylinder?

Unless you’re converted your heating system, moving the cylinder, or the cylinder is leaking, there’s a good chance it doesn’t need replacing.

Manufacturers of both vented and unvented hot water cylinders will provide long warranties. For instance, Worcester Bosch offer a 25-year warranty on their Greenstore cylinders.

The Best Hot Water Cylinders

There’s a tonne of top quality brands selling hot water cylinders.

If you’re looking for a replacement, here are the best cylinders we’ve come across are:

Joule Cylinders

We’ve covered the Joule Cyclone Cylinders here. They are fairly new player to the hot water cylinder market, but they are high quality and reasonably priced. 

Worcester Greenstore

Worcester offer a huge 25 year warranty on their Greenstore cylinders. And, they start as small as 90L with the SC-90, so there’s a cylinder for every type of property.


Gledhill offer a fantastic range of cylinders, and are cheaper than Worcester Greenstore. They’ve also got a good range of direct and in-direct copper cylinders.


Stelflow are made by RM Cylinders. In terms of price, they are on par with Gledhill, but slightly more expensive than the Joule Cyclone we mentioned above.

Finding A Hot Water Cylinder Installer

We’ve got contacts across the UK that fit cylinders, boilers and central heating.

To get free quotes, click here.

Any Questions?

We’re always happy to help.

If you have any questions regarding hot water cylinders, installation costs, or even advice on whether a quote you’ve received is reasonable, leave a comment below. We’ll get back to you as soon as possible.

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  1. Hello, my gledhill electric boiler is not working properly, i have had lots of new elements, it works for a while and then breaks down again. I may need to replace it, it is around 20 years old, any suggestions ?

    1. Hi Susan,

      What Gledhill is it? What volt elements have been used? Have the thermostats been replaced alongside the elements? Is the outflow being replaced quick enough (i.e. the element is covered by water at all times)?


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