The heat transfer fluid WTF B (accessory) offered for solar thermal
systems is also used in heating systems (e.g. holiday homes) as an
antifreeze agent. The freezing point ("crystallization point") of the ready
mixed heat transfer fluid is -24 °C and the maximum frost protection
("setting point") is -32 °C. As it has a lower heat capacity than pure water
but is more viscous, boiling noises may occur under unfavourable system
conditions.
Frost protection down to -32 °C is not required for most heating systems;
-15 °C is usually sufficient. The heat transfer fluid must be diluted 2:1 with
water to set this operating point. This mixing ratio has been tested by
Potterton in relation to its practical suitability for use with condensing
boilers.
Important
Up to a mixing ratio of 2:1, the heat transfer fluid WTF B is
approved as frost protection down to -15 °C for use with Potterton
condensing boilers.
Caution
Keep the installation room frost-free.
If an antifreeze agent is used, pipework, radiators and condensing
boilers are protected against frost damage. For the condensing
boiler to be ready for operation at any time, suitable measures
must also be taken to keep the installation room frost-free. If
applicable, please also note special measures for any installed
domestic hot water calorifiers.
The table shows the relevant volumes of heat transfer fluid and water that
need to be mixed together for varying volumes of water. If other frost
protection temperatures are required in exceptional cases, individual
calculations can be made on the basis of this table.
Water content of
the system
[l]
Volume
WTF B
[l]
Mixing in water
[l]
Frost protec
tion down to
[°C]
50
36
14
-15
100
71
29
-15
150
107
43
-15
200
143
57
-15
250
178
72
-15
300
214
86
-15
500
357
143
-15
1000
714
286
-15
(1) The water for the mixture must be neutral (drinking water quality with no
more than 100 mg/kg chlorine) or demineralised. Please also follow the
manufacturer instructions.
5 Before installation
7703301 - 01 - 16072018
31
