Viessmann Vitodens 200-W B2HA 88 Technical Data Manual page 52

System Design
System Design Considerations
System layout
The max. boiler water temperature for space heating
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and DHW production is for models B2HA 88 to 530.
To minimize distribution losses, Viessmann
recommends that the heating and domestic hot water
systems be based on a maximum boiler supply
temperature of 185°F (85°C).
Due to the low return temperatures required for gas
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condensing, no mixing valves should be used in the
heating circuit whenever possible. If mixing valves
are required, e.g. for multi-circuit systems or
underfloor heating systems, only 3-way mixing valves
must be used.
Do not use 4-way mixing valves with condensing
boilers.
Underfloor heating systems
For underfloor heating systems Viessmann recommends
the use of plastic tubing with an oxygen diffusion barrier
in order to prevent the diffusion of oxygen through
tubing. If plastic tubing without an oxygen diffusion
barrier is used in underfloor heating systems, Viessmann
recommends that such systems be separated from the
boiler with a heat exchanger.
Underfloor heating systems and heating circuits
containing a very large volume of water must be
connected to the boiler via a 3-way mixing valve; please
refer to the applicable installation example in this manual.
Vitodens 200-W B2HA 88-150, 311- 530 Technical Data
(continued)
Oxygen diffusion barrier underfloor tubing
The boiler warranty does not cover leaks resulting from
corrosion caused by the use of underfloor plastic tubing
without an oxygen diffusion barrier. Such systems must
have the non-oxygen diffusion barrier tubing separated
from the boiler with a heat exchanger. Viessmann
recommends the use of underfloor plastic tubing with
an oxygen diffusion barrier.
Warranty
Our warranty does not cover damages resulting from
the following:
- installation or service by unqualified and unlicensed
personnel.
- attempting to perform any repair work on the boiler
other than that mentioned in the boiler literature.
- tampering with or attempting, without Viessmann
permission, to readjust the factory settings of the;
-combination gas valve
-combustion air opening of the burner blower
- leaks resulting from corrosion caused by the use of
underfloor plastic tubing without an oxygen diffusion
barrier. For detailed warranty information, please read
warranty sheet supplied with product.