Domestic Hot Water

Historically a domestic hot water storage system used in the UK consisted of a copper cylinder and cold water storage tank situated in the loft. The cylinder was required to have an open vent pipe that ran from the cylinder back to the cold storage tank and predominantly out of the loft as an overflow pipe. This brought with it a number of disadvantages, Poor shower performance, possible water contamination and noisy cistern filling along with the potential freezing hazard and likelihood of unbalanced hot and cold water supplies.

So what is an unvented cylinder?
Unvented cylinders or mains pressure cylinders as they are sometimes referred to are increasingly the preferred choice for many Developers and end users when it comes to hot water cylinders. Since the early 1980s when unvented cylinders were specified and installed in the UK the market has increased along with demand year on year, and there are over 30 different manufacturers now offering various different models of cylinder.

A mains pressure unvented hot water storage system is a hot water cylinder, where the water contained within it is held at some pressure above atmospheric. It is normally supplied direct from the mains and the system is sealed to the atmosphere. This type of system does not require a cold water storage tank, thus saving space and due to working at higher pressures the cylinders are designed to higher standards. Unvented cylinders have many benefits over traditional systems as the hot and cold water supply to all outlets will be a higher pressure which allows for greater system design and flexibility, offering a wider choice of taps and mixers. Cylinders can be sited almost anywhere and provide High performance showers without the need for booster pumps.

With so many different types of cylinder now available how can you make that important decision and choose the right model for the right application at Artizan heating we pride ourselves on offering expert advice on the systems we promote and with many years experience we only promote systems that we know will suit our customers applications and offer the best aftercare support. With the installation of multi-bathroom dwellings, customers are demanding a system that meets their individual requirements. So more than ever it is essential to obtain both pressure and flow readings before promoting the use of such systems. It is true to say that mains fed systems such as unvented cylinders will only be as good as the main supply that feeds them, and with pressures in certain areas of the UK being reduced, it is vital that the mains supply is tested before incorporating an unvented cylinder into any design.

So what can you do when the main supply will not support a mains fed system! Or the property has several hot and cold outlets to feed and requires a greater supply! Renewing the main or installing break-tanks are some options. The other option could be the Dualstream system.

The Dualstream system utilises an accumulator, which has a controlled butyl diaphragm that stores cold mains water at mains pressure and a stainless steel unvented cylinder. When a tap or shower is turned on the accumulator enhances the main supply and helps maintain the pressure to all hot and cold outlets regardless of the flow rate on the incoming main supply. There is an air charge in the top of the accumulator to help force the water from the vessel into the hot and cold supplies, sized correctly the system will run more than one outlet at the same time stabilising pressures and increasing flow rates at taps, showers and baths. The systems are ideal for properties with poor mains supplies or multi-bathroom outlets. With sizes from 125 litres to 500 litres, and twin coil cylinders for use with solar, systems can be designed to suit most applications.

The difference between standard unvented cylinders and the Dualstream system is the use of the accumulator, which has been designed to increase flow rates at mains pressure. This patent product has many benefits and can be used in many applications to do with flow rate issues. The Coldstream range of Accumulators from GAH Heating Products can be installed on mains fed systems to provide increased flow rates and stabilize pressure problems on existing mains fed appliances. And can even be installed on a main supply feeding a Combination Boiler. The accumulator can be installed anywhere on the main supply entering the property, basement, utility, loft and Artizan heating work closely with GAH to provide you with expert advice.

Indirectly heated cylinders are designed to be run in conjuction with an external heat source, gas, oil central heating boiler. They are often supplied with an immersion heater as back-up.

Directly Heated cylinders are generally heated by electric immersion heater supplied with two or more immersion heaters and can take advantage of "economy tariff" electricity.

Cylinder Size
Both direct and indirect mains pressure cylinders are available in various sizes for most applications, from 100 litres to 500 litres.

Controls
Unvented systems have a number of controls built into their design to prevent an uncontrolled supply of heat to the stored water and are generally sold as a package with the controls required.

Maintenance
All manufacturers will provide an initial guarantee for their products. At Artizan Heating we recommend at regular intervals the system should be checked to ensure the correct operation of valves and filters and as part of the benchmark warranty conditions.

We install a full range of boilers including those from:-