System Design Considerations - Viessmann VITOGAS 100 Technical Data Manual

System Design Considerations

The Vitogas 100 is designed for closed loop,
forced circulation hot water heating systems
only.
Boiler selection
The boiler model size should be based on an
accurate heat loss calculation of the
building. The boiler selected must be
compatible with the connected radiation.
Venting
For proper operation of the Vitogas boiler, all
products of combustion must be safely
vented to the outdoors, while ensuring that
flue gases do not cool prematurely.
It is critical that the chimney system be
properly designed to handle the relatively
cool flue gas temperatures produced by the
Vitogas boiler.
Flue gases which cool too quickly and
produce condensation lead to damages if
the chimney diameter is too large and the
chimney system is not well insulated.
If a calculated chimney diameter lies
between two values, the larger diameter
should be selected.
The Vitogas 100, GS1 boiler is a Category I
boiler as defined in the ANSI Z21.13 CSA
4.9 Standard. Use approved vent material
(such as B-vent) only.
Intermediate section
Use the shortest possible path between the
boiler and the chimney. A maximum of two
elbows may be installed in the intermediate
section. Avoid the use of two level 90°
elbows.
The intermediate section must be sealed gas
tight at the boiler vent pipe collar and at the
chimney connection. Ensure any test port
for combustion values is sealed as well.
The chimney connection between the boiler
vent pipe collar and the chimney must be
installed with insulation. We recommend
consulting a reputable chimney installer for
advice in project-specific circumstances.
Warranty
Our warranty does not cover damages
resulting from the following:
– installation or service by unqualified and
not licensed personnel
– corrosion caused by flue gas condensation
due to low boiler water and/or return
water temperatures
– operation with contaminated fill and
supplementary feed water
For detailed warranty information, please
read warranty sheet supplied with product.
Combustion air supply
The boiler must not be located in areas or
rooms where chemicals containing chlorine,
bromine, fluorine, or other corrosive
chemicals are stored. Examples include
refrigerants, bleach, paint, paint thinner, hair
spray, cleaning solvents, water softener
salt, etc. The combustion air must not be
contaminated with any amount of the above
mentioned chemicals.
Boiler should never be installed in areas
where excessive dust, high humidity, or risk
of frost exist. Ensure adequate ventilation
and supply of fresh combustion air.
Consult Viessmann if uncertainties exist in
regard to a suitable boiler installation
location.
This boiler/burner unit needs clean fresh air
for safe operation and must be installed so
that there are provisions for adequate
combustion and ventilation air.
For gas or propane, use the "Natural Gas
Installation Code CAN/CSA-B149.1 or
B149.2" (Canada), or "National Fuel Gas
Code ANSI Z223.1" (USA), and/or
provisions of local codes.
The sizing methods outlined in the above
codes should be used when installing a
round duct to supply combustion air from
the outside.
System layout
The boiler water temperature limit is factory
set to 167 °F/75 °C.
The boiler water temperature limit can be
increased by altering the adjustable high
limit to increase the supply water
temperature.
To minimize piping losses of the system
however, we recommend that the radiation
and domestic hot water production in the
system be designed for a 158 °F/70 °C
boiler supply water temperature.
System Design Considerations
Water quality
Treatment for boiler feed water should be
considered in areas of known problems,
such as where a high mineral content and
hardness exist. In areas where freezing
might occur, an antifreeze may be added to
the system water to protect the system.
Please adhere to the specifications given by
the antifreeze manufacturer. Do not use
automotive silicate based antifreeze. Please
observe that an antifreeze/water mixture
may require a backflow preventer within the
automatic water feed and influence
components such as diaphragm expansion
tanks, radiation, etc. A 40% antifreeze
content will provide freeze-up protection to
-10 °F/-23 °C. Do not use antifreeze other
than specifically made for hot water heating
systems. System also may contain
components which might be negatively
affected by antifreeze. Check total system
frequently when filled with antifreeze.
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.
Low water cut-off
A low water cut-off may be required by local
codes. If boiler is installed above the
radiation level, a low water cut-off device of
approved type must be installed in all
instances. An approved type low water
cut-off device must be provided by the
heating contractor. Do not install an
isolation valve between the boiler and the
low water cut-off.
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