Installation | Ariston Unvented Hot Water Storage Cylinders guide

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2.INSTALLATION

2.1WATER REGULATIONS

2.2BUILDING REGULATIONS

2.3HOW THE APPLIANCE WORKS

These regulations (byelaws in Scotland) ensure a good supply of wholesome water, and that only approved materials, pipes and fittings are used to convey water.

These are a statutory document and take priority over all other regulations and recommendations. The installation of an unvented hot water storage cylinder is classified as a “Controlled Service” and Regulation G3 applies. To meet the requirements of the Regulation, installation of an unvented system should be undertaken by a “competent installer”.

All installations of unvented hot water storage systems having a capacity of more than 15 litres should be notified to the relevant Local Authority by means of building notice or by the submission of full plans. It is important to note that it is a criminal offense to install an unvented hot water storage system without notifying the Local Authority. The installation of the unvented cylinder and hot water system must comply with BS 6700 and the HSE Legionella Code of Practice.

The immersion heater(s) are controlled through a thermostat which senses the water temperature. The operating temperature can be pre-set by adjusting the spindle in the head of the thermostat. In addition to the thermostat there is a thermal cut-out incorporated if the thermostat fails and the water temperature rises too high. Once the cut-out operates it can only be re-set manually after the fault has been rectified.

Indirect models have dual thermal controls. In addition to the above there is a separate cylinder thermostat and thermal cut-out for controlling the indirect circuit. Again the thermal cut-out operates if the cylinder thermostat fails, by disconnecting the live feed (call for hot water) from the programmer.

Classico (STD/STI) models have magnesium anodes provided to prevent corrosion of the cylinder tank.

All High Capacity (STD/STI) 500 litre models, Wall-hung(ST) units and the Contract (STD/STI) Floor-standing models utilise the ProTech anti-corrosion system (electronic anode).

The factory fitted temperature & pressure relief valve at the top of the cylinder is a safety device to back-up the thermostat(s) and thermal cut- out(s). It works by sensing an excess in water temperature or pressure and releasing the hot water into a discharge tundish and drain.

The cylinder will only work in the vertical position. The inlet pipe needs to deliver cold water to the bottom of the tank. When water is heated it expands. To accommodate this increase in volume an expansion vessel is provided. A cold water combination valve is also provided in two pieces, loose jointed for ease of installation. These comprise a combined line strainer/pressure reducing valve and core non-return valve/expansion relief valve.

The strainer prevents any debris entering the other controls. The pressure reducer ensures the correct operation of the expansion vessel, and prevents any damage to the control valves through too great a pressure.

The non-return valve ensures the water expansion is forced into the expansion vessel and prevents contamination of the mains cold water supply. The expansion relief valve will discharge expanded water to the discharge tundish if the expansion vessel fails.