Sizing The Heat Exchanger, Primary Circuit; Heating Circuit Distributor And Heat Distributor; Sizing Of The Heating Water Buffer Cylinder; Heating Water Buffer Cylinder For Optimised Runtimes - Viessmann VITOCAL 222-G Technical Manual

Design information

Sizing the heat exchanger, primary circuit

10 °C 8 °C
A B
6 °C 4 °C
A Water
B Brine (antifreeze mixture)
Selection list for plate heat exchangers for water/water heat pumps
Plate heat exchanger, soldered (do not clean; replacement part)
Compact heat Refrigerating
pump capacity
Type in kW
Vitocal 222-G/242-G
BWT 106
BWT 108
BWT 110
Vitocal 333-G / 343-G
BWT 106
BWT 108
BWT 110
Plate heat exchanger, threaded (requires cleaning)
Heat pump Refrigerating
capacity
Type kW
Vitocal 222-G/242-G
12
BWT 106
BWT 108
BWT 110
Vitocal 333-G / 343-G
BWT 106
BWT 108
BWT 110

12.7 Heating circuit distributor and heat distributor

Different heating water flow temperatures are required depending on
the heating system design.
The heat pumps reach a maximum flow temperature of 60 ºC.
To enable the heat pump to operate in mono-mode, install a low tem-
perature heating system with a heating water flow temperature of
≤ 60 °C.

12.8 Sizing of the heating water buffer cylinder

Heating water buffer cylinder for optimised runtimes

V Q · (20 to 25 litres)
HP WP
Q = Absolute rated heat pump heating output
WP
V = Heating water buffer cylinder volume in litres
HP

Heating water buffer cylinder for bridging periods when the supply is blocked

This version is offered for heat distribution systems without additional
cylinder mass (e.g. radiators, hydraulic fan convectors).
*17 230 V appliances
VIESMANN
68
(cont.)
Flow rate
Well circuit Primary circuit
(water) (brine)
in m 3 /h in m
1440
*17
6.7 (6.5 )
8.5 (8.5) 1820
11.0 (10.7) 2350
6.8 1450
9.1 1950
11.4 2440
Plate heat
exchanger
Part no.
7248 331
*17
6.7 (6.5 )
8.5 (8.5) 7248 332
11.0 (10.7) 7248 333
6.8 7248 331
9.1 7248 332
11.4 7248 333
Note
Fill primary circuit with anti-freeze mixture (brine, min. –5°C).
The operational reliability of a water/water heat pump improves when
it is used with a primary circuit heat exchanger. Subject to the correct
sizing of the primary pump and the optimum layout of the primary cir-
cuit, the coefficient of performance of the water/water heat pump will
be reduced by a maximum of 0.4.
We recommend the use of the threaded stainless steel plate heat
exchanger from the Viessmann Vitoset pricelist (manufacturer: Tranter
AG); see the following selection table.
Pressure drop
Well circuit
(water)
3 /h in kPa
1510 15.2
1920 8.1
2480 13.3
1530 15.6
2050 9.3
2670 14.2
Flow rate and pressure drop in the primary circuit are safeguarded by
the integral circulation pumps, provided the total pressure drop from
the primary circuit heat exchanger and pipework does not exceed the
maximum external pressure drop of the heat pump (see "Specifica-
tion").
The lower the selected maximum heating water flow temperature, the
higher the seasonal performance factor of the heat pump.
A heating circuit pump and a safety valve (3 bar) for the heating circuit
side are already integrated into the appliance. Provide a diaphragm
expansion vessel on site that is sized to match the heating system. For
this, take the heating water volume of the devices into account.
Example:
Type BWT 110 with Q = 10.2 kW
WP
V = 10.2 · 20 litres = 204 litre cylinder capacity
HP
Selection: Vitocell 100-E with 200 litre capacity
Vitotrans 100
Primary circuit plate heat
(brine) exchanger
in kPa Part no.
14.0 3003 492
8.2 3003 493
13.4 3003 493
14.4 3003 492
9.3 3003 493
14.3 3003 493
VITOCAL