System Design Considerations - Viessmann VITOCROSSAL 300 Technical Data Manual

System Design

System Design Considerations

IN THE COMMONWEALTH OF MASSACHUSETTS...
- this product shall be installed by a licensed plumber or
gas fitter.
- the flexible connector (if used) cannot exceed 36".
- any level type shutoff used must be of tee handle
type.
Boiler location
As a direct vent appliance, the Vitocrossal 300 CU3A can
be installed for room air independent operation (sealed
combustion) regardless of size and ventilation method
of the room in which it is located.
The Vitocrossal 300 CU3A can be installed, for example,
in the main living area of a house, in non-ventilated utility
rooms, cupboards, closets and alcoves with no clearance
required from combustible materials, as well as in attics
with a direct outlet for the flue gas/fresh air system.
Follow all local and national codes.
Flue gas system
Viessmann PP(s) (Polypropylene) concentric flue gas/
fresh air systems for room air independent operation
(sealed combustion) and side wall venting are tested to
ANSI Z21.13 - CSA 4.9 (latest edition) and are certified
together with the Vitocrossal 300 CU3A boiler as a
constructional unit.
The Vitocrossal 300 CU3A boiler may also be vented,
using an AL29-4C® special stainless steel, single-wall, room
air dependent or independent venting system (UL listed for
category IV), polypropolene PP(s) or CPVC single wall room
air dependent or independent venting system (listed
to ULCS636 or UL1738) for CAT IV appliances.
For a more detailed description of the direct vent and
single-wall vent system, please refer to the Vitocrossal 300
CU3A Venting System Installation Instructions.
Flue gas temperature protection
Flue pipes used for the Vitocrossal 300 CU3A are suitable
for max. flue gas temperatures of up to 230°F (110°C).
No flue gas temperature protection is required as the
maximum permissible flue gas temperature is not
exceeded in any operating condition or in the event of
malfunctioning.
Total permissible hardness of the fill and top-up water
Total heating output
MBH
170
>170 to  682
>682 to 170
>2050
ppm - parts per million
gpg - grains per gallon
28
Specific heating volume
<5 USG per 3412 BTU
300 ppm 17.5 gpg
200 ppm 11.7 gpg
150 ppm 8.8 gpg
2 ppm 0.11 gpg
Vitocrossal 300 CU3A 26 to 57 Technical Data
Low water cut-off
A low water cut-off may be required by local codes.
If the 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.
Water connections
Vitocrossal 300 CU3A boilers can be used in any fully
pumped hot water heating system.
Minimum system pressure is 14 psig.
Chemical corrosion protection products
Corrosion does not typically occur in sealed heating
systems which have been correctly installed and are
correctly operated.
Many manufacturers of plastic pipes recommend the
use of chemical additives. In this case, only those
commercially available corrosion protection products
approved for boilers with domestic hot water heating
via single-wall heat exchangers (instantaneous plate
heat exchangers or DHW tanks) must be used.
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. Maximum antifreeze
content is 50% for the Vitocrossal 300 CU3A boiler.
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.
Advise system operator/ultimate owner that system is
filled with a glycol mix. The heating contractor must
provide a MSDS (Material Safety Data Sheet) for the
antifreeze used to the system operator/ultimate owner.
 5 USG per 3412 BTU to
<13 USG per 3412 BTU
200 ppm 11.7 gpg
150 ppm 8.8 gpg
2 ppm 0.11 gpg
2 ppm 0.11 gpg
 13 USG per 3412 BTU
2 ppm 0.11 gpg
2 ppm 0.11 gpg
2 ppm 0.11 gpg
2 ppm 0.11 gpg