EcoSolar Energy Conscious Design Limited
17
•
open vented, a vent pipe will extend from the cylinder through the roof and terminate some
distance above the roof with an open end.
•
valve vented, a thermal / pressure and / or pressure relief valves will be installed to relief any
excess pressure or heat from the cylinder.
Low Pressure Systems
Low pressure hot water cylinders are generally fabricated from copper, insulated and have a
specification stamped on the cladding over the insulation providing details of pressure rating etc.
Copper cylinders are historically proven and have a good resilience to temperature, however they are
generally only available as low (7.6m head) or medium pressure (12.2m head).
Connection to an existing hot water cylinder, with no solar system
connections
In many retrofit installations the solar system will be installed on to a cylinder that has no spare
cylinder connections. Most of these will require the installation of a four way inlet which allows the
cold water supply and warm water returns from the collector to be installed in to the existing cold
water connection. Alternatively spare lower connections can be utilised.
Where the four-way inlet is required, reference should be made to the existing hot water cylinder to
determine any limitations. Some cylinders have a bottom entry cold feed and have no solar
connections. Many hot water cylinders have a dispersion plate located above the bottom entry inlet
thereby not allowing the 10mm dispersion tube, which is connected on the 4 way inlet, to be inserted
in to the cylinder from the bottom. This dispersion plate may, in some cases, be drilled, to allow the
dispersion tube to pass through. Reference should be made to the cylinder manufacturer to confirm
that this is acceptable.
Connection to a hot water cylinder with solar system connections
These cylinders will either have connections just made into the hot water cylinder and allow the
stored water to circulate through the solar collector, direct system, or have a heat exchanger installed
within or encompassing the cylinder, indirect system.
