________________________________________________________________________________
24
AST 14 C 255/00
DHW FLOWMETER
(only for CTFS version)
The DHW flowmeter is fitted with an internal turbine for metering
the volume while DHW is being drawn.
Besides determining the minimum quantity of DHW needed to
start the boiler
(2.5 l/min ON and 2 l/min OFF)
, it calculates the
necessary output to be developed in DHW mode at that
particular moment, taking into consideration:
- the temperature difference between set temperature
and inlet cold water temperature;
- drawn water flow rate.
This improves the production of domestic hot water, benefiting
both user and efficiency
(three-star efficiency instead of the 2-star
efficiency obtained with the standard flow switch)
.
The flowmeter transmits a pulse signal which is received and utilised by the electronic
board as the frequency used to determine the litres to be drawn:
l/min imp/l
Imp/l
MIN
Imp/l
MAX
Hz
Hz
MIN
Hz
MAX
2
410
377 443
13.7
12.6 14.8
4
443
408 478
30
27.6 32.4
6
452
416 488
45.2
41.6 48.8
8
457
420 494
61
56.1 65.9
10
459
422 496
76.4
70.3 82.5
12
463
426 500
92.6
85.2 100
Warning:
it is not possible to simulate any DHW request with the flowmeter, however it is
possible to delay the reading of the signal with the parameter P15.
Depending on the different output rates, the difference between one flowmeter and
another lies in the flow rate limiting device (flow regulator) which determines the
litres/minute that can be drawn at
∆
t 30K: 10 l/min for 24 kW models, 13 l/min for 28 kW
models and 14 l/min for 32 kW models.
KEY
V1 Pump speed I (min)
V2 Pump speed II
V3 Pump speed III (max)
CTFS 28 – 32 kW
V1
V2
V3
