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VARITHERM SMALL SQUARE VAV DIFFUSER
MAINTENANCE & CONTROLLING THE SYSTEM
Maintenance
The moving parts of the VKD Varitherm Small Square VAV diffuser have no maintenance or lubrication requirements. We are often
asked to recommend periodic maintenance procedures and a spare parts stock. Recommended maintenance is to clean the
outer surfaces of the Varitherm Small Square VAV diffuser—nothing else. We do not recommend stocking any spare parts. Our
customers also confirm that stocking is unnecessary.
Controlling the System
References:
•
System Design, p 3, VKD brochure, Form 051.101.
•
Chapters 2.2, 3.1 and 3.2, pp 6, 7 and 8,
DesigningModular VAV Systems, Form 5.2.
Supply Air Temperature
The sources of cooling and heating are controlled from supply air temperature. As with all VAV systems, the goals are to achieve a
constant supply air temperature (may be reset to another constant supply air temperature) and to limit the supply air temperature.
Limits for supply air temperature should be between 50°F/10°C and 68°F/20°C when cooling and between 80°F/26.5°C and
120°F/49°C when heating. The heating temperature limit should be as low as possible. These objectives are best achieved by
modulating chilled water valves, hot water valves and other variable equipment from supply air temperature. On/off equipment
such as DX compressors and electric heat are cycled from supply air temperature. Use a discharge air sensor for the supply air
temperature signal.
Mode change between heating, recirculation and cooling is controlled from room temperature. Signals from one or more room
temperature sensors may be used for mode change. When using more than one sensor, either a "majority rules" or a "cooling
Fig 8. Blow patterns
dominant" approach is recommended.
Static Air Pressure
As with all VAV systems, the fan must run continuously during occupied times. Goals of static pressure control are to provide
3-Way D3
enough static pressure to obtain the required air volume especially at the diffuser farthest from the fan, to avoid diffuser noise by
limiting static pressure at both full flow and turndown and to provide pressure independence or consistent operation as the system
flow changes.
These objectives can be achieved with the usual methods of automatic static pressure control: bypass dampers, discharge
dampers, zone dampers, and fan control (variable speed drives, inlet dampers, etc.). Locate the static pressure sensor as far down
the duct as possible—at least 2/3 down the duct from the first takeoff.
Fig 8. Blow patterns
TK-HC THERMA-FUSER diffuser
FIG. 8 BLOW PATTERNS
APPEARANCE PANEL REMOVED
3-Way D3
3-WAY D3
2-Way Corner D2C
2-Way Opposite D2
TK-HC THERMA-FUSER diffuser
APPEARANCE PANEL REMOVED
MAINTENANCE
The moving parts of the TK Therma-Fuser diffuser have
no maintenance or lubrication requirements. We are often
asked to recommend periodic maintenance procedures and
a spare parts stock. Recommended maintenance is to clean
2-Way Opposite D2
the outer surfaces of the Therma-Fuser diffuser—nothing
else. We do not recommend stocking any spare parts. Our
customers also confirm that stocking is unnecessary.
CONTROLLING THE SYSTEM
References:
•
•
•
•
2-WAY OPPOSITE D2
SUPPLY AIR TEMPERATURE
The sources of cooling and heating are controlled from
supply air temperature. As with all VAV systems, the goals
are to achieve a constant supply air temperature (may
be reset to another constant supply air temperature) and
priceindustries.com/vavdiffusers | VARITHERM SMALL SQUARE VAV DIFFUSER - Manual
to limit the supply air temperature. Limits for supply air
temperature should be between 50°F/10°C and 68°F/20°C
when cooling and between 80°F/26.5°C and 120°F/49°C
when heating. The heating temperature limit should be
as low as possible. These objectives are best achieved by
•
Air Handling and Fan Coil Units Subzoned with Varitherm
Small Square VAV VAV modules, Form 6.7.
•
DX Equipment Zoned with Varitherm Small Square VAV
VAV Modules,Form 6.5.
Fig 8. Blow patterns
TK-HC THERMA-FUSER diffuser
APPEARANCE PANEL REMOVED
3-Way D3
MAINTENANCE
The moving parts of the TK Therma-Fuser diffuser have
no maintenance or lubrication requirements. We are often
asked to recommend periodic maintenance procedures and
a spare parts stock. Recommended maintenance is to clean
the outer surfaces of the Therma-Fuser diffuser—nothing
else. We do not recommend stocking any spare parts. Our
customers also confirm that stocking is unnecessary.
CONTROLLING THE SYSTEM
References:
•
System Design, p 3, TK brochure, Form 051.101.
•
Chapters 2.2, 3.1 and 3.2, pp 6, 7 and 8, Designing
Modular VAV Systems, Form 5.2.
•
Air Handling and Fan Coil Units Subzoned with Therma-
Fuser VAV modules, Form 6.7.
•
DX Equipment Zoned with Therma-Fuser VAV Modules,
Form 6.5.
2-Way Corner D2C
SUPPLY AIR TEMPERATURE
The sources of cooling and heating are controlled from
supply air temperature. As with all VAV systems, the goals
are to achieve a constant supply air temperature (may
be reset to another constant supply air temperature) and
to limit the supply air temperature. Limits for supply air
temperature should be between 50°F/10°C and 68°F/20°C
when cooling and between 80°F/26.5°C and 120°F/49°C
System Design, p 3, TK brochure, Form 051.101.
when heating. The heating temperature limit should be
as low as possible. These objectives are best achieved by
Chapters 2.2, 3.1 and 3.2, pp 6, 7 and 8, Designing
Modular VAV Systems, Form 5.2.
modulating chilled water valves, hot water valves and other
variable equipment from supply air temperature. On/off
Air Handling and Fan Coil Units Subzoned with Therma-
equipment such as DX compressors and electric heat are
Fuser VAV modules, Form 6.7.
cycled from supply air temperature. Use a discharge air
DX Equipment Zoned with Therma-Fuser VAV Modules,
sensor for the supply air temperature signal.
Form 6.5.
Mode change between heating, recirculation and cooling
2-WAY CORNER D2C
is controlled from room temperature. Signals from one
or more room temperature sensors may be used for
mode change. When using more than one sensor, either
a "majority rules" or a "cooling dominant" approach is
recommended.
STATIC PRESSURE
As with all VAV systems, the fan must run continuously
during occupied times. Goals of static pressure control are
to provide enough static pressure to obtain the required air
volume especially at the diffuser farthest from the fan, to
Fig 8. Blow patterns
TK-HC THERMA-FUSER diffuser
APPEARANCE PANEL REMOVED
3-Way D3
2-Way Opposite D2
2-Way Corner D2C
2-Way Opposite D2
1-Way D1
Page 4 of 6
1-Way D1
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MAINTENANCE
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The moving parts of the TK Ther
•
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no maintenance or lubrication req
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SUPPLY
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CONTROLLING THE S
be reset to
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References:
temperatu
•
System Design, p 3, TK broc
when coo
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•
Chapters 2.2, 3.1 and 3.2, pp
as low as
Modular VAV Systems, Form
modulatin
•
Air Handling and Fan Coil Un
variable e
Fuser VAV modules, Form 6.
equipmen
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•
DX Equipment Zoned with T
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Form 6.5.
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STATIC PRESSURE
As with all VAV systems, the fan
during occupied times. Goals of s
to provide enough static pressure
volume especially at the diffuser
avoid diffuser noise by limiting st
flow and turndown and to provide
consistent operation as the system
These objectives can be achieved
of automatic static pressure cont
discharge dampers, zone damper
1-WAY D1
speed drives, inlet dampers, etc.)
sensor as far down the duct as po
the duct from the first takeoff.
7
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