In the UK, horizontal unvented cylinders are commonly installed in lofts, roof spaces, low cupboards, eaves areas and properties with limited headroom. They provide mains-pressure hot water, just like a vertical unvented cylinder, and can supply good flow rates to showers, baths and taps, provided the incoming mains water pressure and flow rate are suitable.

The main benefit is space-saving. If there is no suitable airing cupboard or plant room, a horizontal cylinder can make use of otherwise wasted space. They are also useful in flats, barn conversions, extensions and properties where installation space is awkward.

Our range of indirect unvented horizontal cylinders are listed here :  Horizontal unvented cylinders 

However, there are some disadvantages. A horizontal cylinder can sometimes have slightly poorer hot water stratification compared with a vertical cylinder. Stratification is the natural layering of hot water at the top and colder water at the bottom. In a horizontal cylinder, this separation can be less effective, which may slightly reduce usable hot water volume in some situations.

They can also be more awkward to install and service, especially in lofts. The structure must be strong enough to support the full weight of the cylinder when filled with water, and there must be safe access for maintenance. As with all unvented cylinders, they must be installed by a suitably qualified, “G3”-competent installer.

In simple terms, horizontal unvented cylinders are a good solution when space is limited, but where possible, a vertical hot water cylinder is usually the preferred option for best performance, easier servicing and better hot water layering.