Installation Factors; Number Of Terminals That Can Be Connected; Selection Criteria - AERMEC IDROBLOC C Serie Manual Técnico Y De Instalacion

INSTALLATION FACTORS

A particular feature of the IDROBLOC C module is that it can
supply, with a flow of water at a preestablished temperature, a
number of fan coils whose total chilling efficiency would be
greater than the cooling power delivered by the module.
A plant that can distribute chilled water to a relatively large
number of fan coils, always ready to enter into operation, can
be produced in this way. Naturally the number of these that
can operate simultaneously is limited by the cooling power
available. It will be the user to exclude all fan coils he con-
siders suitable, depending on the number of persons in the
room. To ensure the maximum independence between the
various rooms, it is recommended that fan coils with incorpo-
rated environment thermostat be installed.
Exclusion from summertime operation of some fan coils is
not effected by hydraulically intercepting the single units, but
simply by keeping them switched off. In the latter, the chilled
water circulates with a higher minimum temperature.
In the return piping of the plant, in this case a mix is produced
of water at different temperatures: a hotter flow coming from
the fan coils in operation and practically at the production
temperature that coming from the fan coils that are off. The
temperature of the water at the evaporator input is in this case
the weighted average of the various return temperatures.
This is permitted by the fact that the plates type evaporator of
the IDROBLOC C module can be traversed by a flow much
greater than that of a normal cooler, for like delivered power
values. Thanks also to the incorporated pump's characteristics,
the flow of water may be such as to ensure a thermal excursion
on the evaporator of 2 °C.
Where an excessive number of fan coils is in operation, the
cooling power absorbed by these would be greater than the

NUMBER OF TERMINALS THAT CAN BE CONNECTED

The number of fan coils that can be connected in parallel is
linked to the characteristics of the boiler circulation system and
of the IDROBLOC C: the flow of water in circulation, depen-
ding on the losses in the hydraulic circuit, must be sufficient to
feed each fan coil in a satisfactory way: in any operating con-
dition, a minimal quantity of water must be circulating inside
THE HOT WATER FEED
IDROBLOC C can be fed with a flow of hot water of various
origin which can then distributed to the fan coils; in any
case, to ensure proper system operation, it is a good idea to
check the characteristics of the hot water pump, which must
ensure the right flow of water to the individual users. In fact,

SELECTION CRITERIA

The curves in the "total cooling capacity and total electrical
input power" chapter give the multiplication coefficients with
which to obtain, starting from the nominal values, the chilling
efficiency and the total electric power input upon variation of
the external air temperature and the temperature of the water
produced. The values indicated by these diagrams are with
reference to a constant thermal excursion of the water, of 5 °C.
For different thermal excursions, multiply the chilling efficiency
by the values shown in the following table.
Chilled water thermal excursion
2°C 3°C 4°C
Cooling power correction factor
0,97 0,98 0,99
5°C 7°C 9°C
1,00 1,02 1,04
power made available by the IDROBLOC C module, and there
could therefore be a situation in which the desired well-being
conditions in the environments served are not attained. This
work condition, which is not in any way dangerous for proper
device operation, is signalled on the control panel through the
appearance of the marking " Ht " (only on the "cold only" ver-
sion).
The impossibility of using all the installed fan coils simul-
taneously does not in general constitute a limitation as the
conditioning requirement is in different rooms and at different
times: for example in a residential dwelling, a day zone and a
night zone may be identified, to be serviced alternatively.
In heat pump operation, IDROBLOC C can lay on a flow of
hot water that may be used to heat rooms with. This possibility
means that rooms can be heated in the spring and autumn sea-
sons without having to switch on the boiler. In the same way
as in cooling operation, the number of fan coils that can come
into operation simultaneously depends on the thermal power
delivered by the machine.
In winter operation, the thermal heating capacity must obviou-
sly be sufficient for simultaneous operation of all the terminal
units installed.
If using the IDROBLOC C module as a traditional chiller, the
number of fan coils that can be connected depends on the
cooling power that is available; in this case, all the units instal-
led can operate simultaneously.
Warning: the antifreeze protection is activated only when
the unit is powered, it is therefore recommended to leave the
IDROBLOC C under electric power even in the cold season.
each fan coil.
Determining the number of fan coils that can be connected
is therefore in relation to the total flow of water in backlash,
which is the sum of those needed by the single fan coils to sati-
sfy the thermal load relative to each of these.
the hot water, before being distributed to the users, enters the
IDROBLOC C, where it meets a proportional resister to the
flow rate as shown in the "internal pressure drop in heating
mode with boiler" chart.
The power absorbed is not significantly affected by the heat
range of the water.
The "effective pressure in cooling mode" chart gives the useful
head available for the cooled water distribution system.
The "internal pressure drop in heating mode with boiler" chart
gives the internal pressure drops of the IDROBLOC C at the
various flow rates for water coming from the boiler. Knowing
the characteristic of the circulation system in any boiler present
or, in any case, the head available upstream of IDROBLOC C,
we can calculate the useful head available for the distribution
plant.
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