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ASSA ABLOY Hospitality
66 8003 016-3
3.1.4.7 Connection examples for outputs N, L, RV, Y and W
In HVAC (
Heating Ventilation and Air Conditioning
) systems, a difference is often
made between
2-pipe systems
and
4-pipe systems
.
In a
2-pipe system
there is one pipe in and one pipe out; both pipes either have cold
water or hot water. If there is cold water in the pipes, the air conditioning can only
be used for cooling. If there is hot water in the pipes, the air conditioning can only
be used for heating. In most cases, cold/hot water in the pipes is changed twice a
year (Spring/Autumn) through an actuator connected to the
cool output
on the
thermostat.
In a 4
-pipe system
there are two pipes in and two pipes out; one set of pipes in/out
has cold water and the other set of pipes in/out has hot water. The thermostat can
choose whether cooling or heating is applicable by activating either the
cool output
or the
heat output
on the thermostat.
For a thermostat to know whether the water in a pipe is cold or hot, a
pipe
temperature sensor
is used. There are two types of pipe temperature sensors;
see details
here
.
Figure 19
