Minimum Recommended Return Air Grille Selection Chart
Table 2.
Model
Without Filter
With Filter
Grille Size (m²)
Example of Size
(mm)
Grille Size (m²)
Example of Size
(mm)
SP615/SP623/SP521/BX520/
SP415/SP421
0.26
(400x650)
0.39
(400x1000)
SP623-XA/SP521-XA
0.28
(400x700)
0.42
(400x1050)
SP630/SP530/SP435/BX526
0.36
(400x900)
0.54
(400x1350)
SP630-XA/SP530-XA
0.38
(400x1000)
0.57
(400x1450)
SP430
0.31
(400x800)
0.47
(400x1200)
Note:
Grille sizes are based on maximum airflow with typical Egg-Crate Grille type. For all other types, consult
grille manufacturer’s specifications.
For example a grille with a free ventilation opening measuring 400mm x 750mm, the grille size is 0.4m x 0.75m =
0.3m
2
. This grille would be suitable for a StarPro SP623-XA heater provided the grille does not have a filter fitted.
10. Outlet Guide
The outlet chart provides recommendations based on using the Brivis “SuperSizeGuide” or a system designed using
accepted design principles. These figures also relate to typical size registers and diffusers used on domestic heating
systems i.e. 300mm x 100mm floor registers and 150mm round ceiling diffusers, with 150mm ductwork connection.
For all systems, a minimum number of outlets must remain fully open (this includes both the outlet grille and the
damper in the duct) if the heater is to operate properly without overheating. Similarly, ceiling outlet systems have a
maximum number of outlets that can remain fully open, to ensure that the velocity through each outlet is sufficient.
These maximum ceiling outlet figures relate to fully open outlets, however, the system will operate efficiently with more
outlets open, if it has been properly balanced. There is no maximum number for floor outlets, so the following chart
below lists the typical number of floor outlets for each heater model.
The outlet chart has been divided up into four columns as follows:
A. The maximum number of outlets that should remain fully open for a ceiling outlet system.
B. The typical number of outlets for a floor outlet system.
C. The minimum number of outlets that should remain fully open for floor/ceiling systems where the system does not
have zone dampers installed or, where there are zone dampers but these zones are not operated from a
Brivis Networker Thermostat (e.g. wall switches).
D. The minimum number of outlets that should be fully open for floor/ceiling systems where the system has zone dampers
installed, and these zones are being operated from a Brivis Networker Thermostat using the heater’s on-board zone relays
or a Network 516 module. Systems fitting this description are deemed to have Adaptive Zoning active, hence minimum
outlet numbers are reduced. Where it shows half figures such as 1.5, it is possible to operate with 1 outlet fully open,
and another outlet half closed (such as a bathroom). Refer to Section 12 for balancing guidelines.
Note:
Column D should not be used unless the Brivis Networker has been configured for Adaptive Zoning only.
If not refer to column C instead. For a Brivis ZonePlus configuration please refer to the Brivis ZonePlus Installation
Manual.
Note:
For SP5 & SP6 Internal models, the normal return air pop configuration is side entry, but can be changed to
the end of the fan cabinet if necessary. If this is done, a total of two outlets must be removed from the allowable
maximum number of outlets.
IMPORTANT NOTE – RETURN AIR CONNECTION AT THE END OF THE UNIT (REAR ENTRY)
On applicable models, connecting the Return Air duct to the end of the unit (rear entry) will result in reduced air
flow – for example, when using a Brivis Lay Down Kit. In this situation:
– The total number of outlets normally permitted for a heating system shall be reduced by 2 (refer to the outlet
register chart located on page 20).
– DO NOT USE this configuration in Add-On Cooling applications, unless you ensure Minimum Recommended
Airflow required for the cooling is maintained.
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