RAYBURN
COOKERS
INSTALLATION
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CENTRAL HEATING
Heatranger Gas-fired Models 480CD
This is a condensing boiler and offers considerable flexibility in central heating system design and is compatible for use with most modern systems.
This can include normal open-vented or sealed systems utilizing conventional radiators or underfloor heating. They may be also used in conjunction with 'Heatstore' type hot-water cylinders.
Whilst it is difficult to predict the total number of radiators which can be supplied, it is more appropriate to refer to the radiators stated output and then check that the total is within the maximum output of 23.4kW. Always allow a margin of 10% for pipe-work losses and of course an allowance for the domestic hot water requirements. Thermostatic radiator valves (Trv's) may be used.
As this condensing boiler has a modulating burner, it may be connected to smaller sized heating systems without any loss of efficiency.
A fully pumped, indirect system is required, similar to that shown below, noting that the diameter of the flow and return pipes should be 22mm.
Whatever type of system is used, it must be fully pumped and contain a corrosion inhibitor suitable for an alloy heat-exchanger.
Although no heat is generated by the boiler when only the cooker burner is in operation, the Rayburn does incorporates its own pump over-run control. Therefore it is necessary to provide a bypass loop, in circumstances where zone valves are fitted which can completely close both circuits. An automatic pressure adjusting valve should be fitted to the bypass.
Since these models incorporate a manual reset overheat device, it is possible to use a sealed system as an alternative to the conventional open-vented arrangement. Sealed systems, set to operate at a maximum pressure of 2 bar, will require the appropriate ancillary equipment, such as expansion vessel, pressure relief valve and filling loop.
Time control for the heating system can be obtained by the use of an external programmer. If this is of the 3 channel type, separate control can be achieved for each of the cooking, hot-water and heating functions. Motorised valves should be used to provide the necessary control, in conjunction with cylinder and room thermostats and may be of the 2 port zone type or 3 port mid-position variety.
If under-floor heating is to be used, this should
be a proprietary packaged system, consisting of all the necessary controls etc.
Such systems normally require the water temperature through the plastic pipe
coils to be restricted to a relatively low temperature such as 30-50 degrees C.,
but the Rayburn's boiler thermostat must not be used for this purpose, otherwise
the domestic hot water temperature would be insufficient and damage to the heat
exchanger may result from condensation. Instead, the under-floor equipment
manufacturer will normally supply the necessary thermostats and mixing/blending
valves to control the water temperature to the heating coils. Always refer to
the manufacturers technical literature and instructions.
Thermal store type hot-water cylinders may also be used with these models, in which the heat for the radiators is drawn from the cylinder. Note that two circulating pumps will normally be required. A typical system is shown below, courtesy of Albion Cylinders Ltd and featuring their 'Mainsflow' system.
The system must be installed in accordance with local water bylaws, Building Regulations and British standards and we strongly encourage that the plumbing and electrics be carried out by a competent person.