Baxi PBM-i 20 Manual Del Usuario página 92

WATER CONNECTIONS
The correct operation of the components that help
ensure the safety of the appliance and the system
should be checked regularly:
• make sure the filters are clean
• check operation of the flow switches installed.
• Make sure that the frost protection heaters on the heat
exchanger are powered when the unit is OFF
Water flow to the heat pump must conform to the values
shown in the section on "General Technical Data".
The flow of water must be maintained constant during oper-
ation.
Risk of freezing
The unit must be prevented from freezing at outside air tem-
peratures around 0°C.
The following are recommended:
• use suitable percentages of antifreeze (see "Ethylene gly-
col solutions")
• protect the piping with heating sheaths,
• empty the system, making sure no water remains at the
lowest points in the circuit or there are closed valves
where water may stagnate.
Ethylene glycol solutions
Water and ethylene glycol solutions used as a heat carrier in
the place of water reduce the performance of the unit.
Multiply the performance figures by the values given in the
following table.
The heat pumps must be fitted with a filling/top-up sys-
tem connected to the return line and a drain valve in the
lowest part of the system.
Systems containing antifreeze or covered by specific
legislation must be fitted with low-loss headers.
Water quality
The water used in the system and domestic hot water cir-
cuits must comply with the following characteristics:
Fouling factors
The performance data given refer to conditions with clean
evaporator plates (fouling factor = 1).
For different fouling factors, multiply the figures in the perfor-
mance tables by the coefficient given in the following table.
12 PBM 20÷40 EN
The water content of the unit must be such as to avoid dis-
turbing operation of the refrigerant circuits.
It is recommended to use non-toxic food grade antifreeze,
compliant with the standards in force in the countries where
the unit is used, if domestic hot water production is also fea-
tured.
The antifreeze used must be corrosion inhibited and com-
patible with the water circuit components.
Freezing point (°C)
0 -5
Percentage of ethylene glycol by weight
0 12%
cPf 1 0,985
cQ 1 1,02
cdp 1 1,07
cPf: cooling capacity correction factor
cQ: flow rate correction factor
cdp: pressure drop correction factor
Ph 6-8
Electrical conductivity less than 200 mV/cm (25°C)
Chlorine ions less than 50 ppm
Sulphuric acid ions less than 50 ppm
Total iron less than 0.3 ppm
Alkalinity M less than 50 ppm
Total hardness less than 50 ppm
Sulphur ions none
Ammonia ions none
Silicon ions less than 30 ppm
Fouling factors
(m °C/W) f1
2
4,4 x 10 -
-5
0,86 x 10 0,96
-4
1,72 x10 0,93
-4
f1: capacity correction factor
fk1: compressor power input correction factor
fx1: total power input correction factor
I A
-10 -15 -20
20% 28% 35% 40%
0,98 0,974 0,97 0,965
1,04 1,075 1,11 1,14
1,11 1,18 1,22 1,24
Evaporator
fk1 fx1
- -
0,99 0,99
0,98 0,98
-25