20
2.10 Sizing of the primary circuit
The primary circuit will be sized in order to satisfy the flow necessary to each ModuSat TP
installed in each apartment. The total flow D supplied by the circulating pumps of the boiler
room being the sum of the individual flows of each ModuSat TP, is:
The sizing of the piped circuit constituting the primary circuit could be carried out in order
to obtain a self-balancing of the installation. The diameter of the rising main primaries will
be selected so that the pressure loss is weak compared to each apartment branch
pipework. The reduction in diameter between each branch connection will be limited or
even better non-existent. The use of a speed lower than 1 m/s, for example 0,5 m/s will be
optimal.
This way, the apartments closest to the boiler room will not require a very reduced setting
of the balancing valves. A diameter of 22 mm will be optimal for branches towards each
apartment. The pressure loss of each satellite branch is defined by the loss through
energy meter, the dirt separator, the 2-way valve, the pipework and the pressure loss of
the PHE in the ModuSat TP. The total pressure loss is 1,5 m at 1000 litres per hour.
In order to guarantee the hydraulic independence of the boilers and of the installation, a
mixing header is installed between the boilers and the primary distribution system. Use
either Evinox headers or Evinox packaged boilers with built in headers.
2.11 Design of the boiler room
The ModuSat TP’s provide each apartment with heating and hot water, which is supplied
by a primary circuit coming from a central boiler room. When the boiler room supplies one
or more buildings, its power usually exceeds 72kW and it must satisfy the regulations
relating to this size of plant.
2.11.1 Determining the kW load required for the boiler plant
The ModuSat TP can be classified in the system of production of hot water with PHE. The
power of the boiler room for heating will be calculated in a traditional way starting from the
losses of the building and the power absorbed for the production of domestic hot water
(increased by a coefficient, which will take into account the losses of distribution: for
example x 1.05).
However the boiler must be designed to satisfy the peak demand corresponding to the use
of domestic hot water considering that for DHW each apartment needs 25-30 kW
The peak hour period, taking into account the natural proliferation of collective housing
buildings, enables the power for heating and domestic hot water not to be added. A
coincidence factor has been defined statistically for centralised hot water production
systems.
See the table below (ref. GDF/SDIG gas fired collective heating).
N = number of standard housing units T = peak period in hours S = Coincidence factor
To Next Page
Loading...
