ISSUE 2016 Rev 1 - Installation Manual
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RM Cylinders
may exceed 10 bar, then an additional upstream pressure reducing device should be fitted.
The mains supply pipe-work should be a minimum of 22mm, which may entail upgrading the existing 1/2” (15mm) cold mains pipe-work.
The water supply must be of a wholesome water quality, defined as Fluid Category 1 in the Water Supply Regulations 1999. In areas of hard
water content greater than 200ppm, treatment for this should be installed.
Electric Supply
This appliance must be earthed. It is suitable for a 240 volt A.C. supply only. The electrical installation must be carried out by a competent
electrician and be in accordance with the latest I.E.E. wiring regulations.
Ensure the electrical supply is isolated before making any connections to the cylinder.
GENERAL INSTALLATION AND COMMISSIONING
Cylinder Connections
The standard pipework connections on the cylinder are 22.0mm compression.
Should imperial ¾” tube be used then imperial ¾” olives are required for successful connection to the cylinder.
Cold Mains Pipework
The cold mains pipework should be a minimum of 22mm, through to the cylinder installation. Care should be taken not to run cold water
pipes adjacent to hot water or heating pipework, thus minimising any heat transfer. Install an isolating valve (not supplied) to the cold mains
pipework. Typically, a 22mm BS1010 stopcock or a quarter turn full-bore lever valve should be used, do not use a screwdriver slot, or other
similar valves.
Make the connection to the cold feed of the cylinder, incorporating a drain valve.
Inlet Control Set
The inlet control set comprises of a 3.0bar pressure reducing valve, 8.0bar expansion relief valve, non return valve, in-line strainer, 22mm
compression connections for cold entry, outlet to the cylinder and an outlet for a balanced cold supply. The inlet control must be positioned
above the Temperature and Pressure Relief Valve (TPRV) that is mounted on the side of the cylinder. This position ensures the cylinder does
not have to be drained in order to service the inlet control set. Ensure the directional flow arrow on the inlet control set follows the required
flow of water.
See schematic diagram.
A balanced cold supply is necessary if there are to be any showers, bidets, or monobloc taps in the installation. Connection to the balanced
cold outlet will facilitate this requirement ensuring both hot and cold outlets are automatically balanced upon filling.
Expansion of Heated Water
The expansion of heated water in the cylinder is accommodated by an entrapment of air in the upper section of the cylinder. This is separated
by a composite disc interface which rises and falls as the stored water heats and cools. The required levels of water and air are established
automatically upon filling and require no specific commissioning. Servicing is required -
see service section
In usage there may be occasions when heated hot water pressure may rise to approaching 8.0bar which may affect some terminal fittings. To
overcome this, consideration should be given to installing a 3.0bar pressure control valve
(available from RM Cylinders)
, to the hot outlet
pipework of the system.
Hot Water Pipework
The main section of hot water distribution pipework should be installed in 22mm, which can be reduced to 15mm and 10mm dependent on the
type of tap. The volume of the hot draw off pipework should be kept to a minimum so the transfer of the hot water to outlets is as quick as
possible. Do not use monobloc mixer taps or showers if the balanced cold connection is not provided, as the unit will back pressurise and
result in discharge. Ensure that the top of the vessel is accessible for servicing.
Secondary Circulation
Where secondary circulation is required a potable water circulator should be used in conjunction with a non-return check valve to prevent any
backflow. Larger secondary circulation systems may require an external expansion vessel should the increased expansion requirement be
greater than can be accommodated within the cylinder. A bespoke secondary return connection is supplied on 210, 250, 300 single coil
indirect and twin coil indirect models. On smaller sizes, the return can be introduced into the cold feed pipe between the inlet control set and
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