Pressurised hot water systems are often called unvented systems. In an unvented system, incoming pressurised cold water typically enters a hot water tank suitable for pressurised water up to 10 -13 bar where it is heated either directly by means of electrical immersion (direct); or by means of heat exchanger coils within the vessel (indirect). Traditionally, houses would use a single coil fed from the gas/oil boiler. However, if one chooses to integrate solar collectors a second coil is required. Cold water from the mains is delivered to the base of the cylinder, the water is heated. Then, when a tap or shower is turned on the mains water pressure pushes the hot water out.
These mains pressure cylinders provide quicker heat recovery than the low pressure open vented cylinder, i.e. it takes less time to heat up.
Advantages of Pressurised hot water systems
There are a number of advantages with using an unvented hot water cylinder. For example:
- High water pressure - great for showers so no need for booster pumps
- Balanced water pressure at hot and cold taps/faucets
- Balanced shower pressure - allowing for safer temperature control
- Fast filling baths.
- Potable (drinking) water at all taps.
- Better high pressure terminal fittings - such as taps/faucets and valves
- No separate cold water storage cistern/tank - enabling loft conversion
- Improved cylinder location flexibility due to mains water pressure
- Quicker to install than an open vented cylinder and its associated fittings
At Midland Heating & Plumbing, we can provide the design, supply, installation, and commissioning of complete pressurised domestic hot water systems.
