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General Design Considerations
The wall chosen for the boiler should be level and capable of supporting the weight of the unit when full of water as shown in
Section 4
. The discharge pipework for the safety valves must have a minimum fall of 1:200 from the unit to a safe discharge
point. All exposed pipework and fittings on the boiler should be insulated, and the unit should NOT be fixed in a location
where the contents could freeze.
In new systems, pipes should be insulated to comply with building regulations, the maximum permissible heat loss is indicated
in the table below, and labelled accordingly as follows:
i. Primary circulation pipes for domestic hot water circuits should be insulated through their length, subject only to practical
constraints imposed by the need to penetrate joists and other structural elements.
ii. All pipes connected to hot water storage vessels, including the vent pipe, should be insulated for at least 1 metre from
their points of connection to the cylinder (or they should be insulated up to the point where they become concealed). In
replacement systems, whenever a boiler or hot water storage vessel is replaced in an existing system, any pipes that are
exposed as part of the work or are otherwise accessible should be insulated as recommended for new systems or to some
lesser standard where practical constraints dictate.
Insulation of pipework
Further guidance on converting heat loss limits to insulation thickness for specific thermal conductivities is available in TIMSA
“HVAC guidance for achieving compliance with Part L of the Building Regulations”.
The
Gabarrón Mattira combi boiler is designed for use with single bathroom properties only and is capable of
a delivery up to 12 L/min hot water flow rate.
Mains Water Supply
Existing properties with a 15mm supply will be satisfactory provided the local mains pressure is good. For new properties,
the communication and service pipe into the dwelling should be a minimum of 22mm (usually in the form of a 25mm MDPE
supply). The optimum performance is achieved if the inlet pressure is 3 bar dynamic. However, the Gabarrón Mattira combi
boiler will function with lower inlet pressures, but this will reduce the performance. For optimum performance, 15 L/min
incoming mains flow should be present; however the
Gabarrón Mattira combi boiler will work at lower flow rates, although
performance will be affected. Normally, the Gabarrón Mattira combi boiler provides in excess of 10 L/min in most
conditions. Flow rates for ALL mains pressure systems are subject to district pressures and system dynamic loss. Particularly
on larger properties, the pipe sizes should be calculated in accordance with BS EN 806-3:2006 and BS 8558:2011.
Mains Water Connection
A ½” BSP thread is provided on the boiler for connection to the incoming mains cold water supply. A 1/2" x 22mm
connection fitting is supplied to join the pipe work to the boiler connection. The installation of a full bore isolation valve on
the mains water supply to the boiler is required (in close proximity to the boiler location). An internal non-return valve
within the Group combination valve prevents possible back-flow should the water main fail.
Pipe outside diameter
Maximum heat loss
15mm
7.89W/m
22mm
9.12W/m
28mm
10.07W/m
35mm
11.08W/m
