Sensing Element20K Thermistor
OutputResistance (passive)
Probe Range-40 to 221°F (-40 to 105°C)
EnclosureBAPI-Box 2 IP66 / NEMA 4
Accuracy±0.36°F (±0.2°C)
Warranty5 Year
BAPI BA/20K-O-BB2-TS is a passive outside air temperature sensor. The 20K thermistor element sends a resistance signal directly to a controller analog input, and the vented polycarbonate shield keeps the sensor out of the sunlight while allowing air to circulate. BAPI rates the probe for -40 to 221°F (-40 to 105°C) and specifies ±0.36°F (±0.2°C) accuracy.
Specifications on this page are taken from BAPI datasheet “Outside Air Units” (B50-B51), Rev. 10/05/23, and from “Outside Air Temperature Sensors BA/#-O Installation & Operations” (20909_ins_OSA_Passive), rev. 02/10/21.
Best For
- Outdoor-mounted outside air temperature measurement
- Sites exposed to rain, snow and large temperature swings
- High humidity outdoor sites, rated 0 to 100% RH, non-condensing
- Shaded wall mounting four feet above the ground or roof
- Direct connection to a controller analog input on twisted pair
Key Features
20K Thermistor ElementNTC, 2 wire. Resistance temperature output.
Vented Shield ProbeVented polycarbonate shield, 1/2 in. OD. Probe length 1.2 in. with 1/2 in. NPT threads. Shades the sensing element and allows air circulation. BAPI still requires the unit itself to be mounted in the shade; the shield does not permit direct-sun installation.
BAPI-Box 2 EnclosureNEMA 4, IP66. UV-resistant polycarbonate, UL94V-0. Two 1/2 in. NPSM plus three 1/2 in. drillable ports. 4.91 in. (124.8 mm) H x 2.82 in. (71.6 mm) W x 2.35 in. (59.7 mm) D.
Etched Teflon Leadwires22 AWG stranded, Etched Teflon, plenum rated. BAPI equips the Outside Air Units with etched Teflon leadwires and states the units can withstand high humidity and condensation in real world outdoor conditions. The published environmental humidity rating remains 0 to 100% RH, non-condensing.
Closed Cell Foam Wall GasketClosed cell foam, impervious to mold. Compresses to about 50% of its thickness to seal against the wall surface.
Terminal Strip ConnectionTerminal strip connection inside the enclosure in place of a direct leadwire termination.
Technical Specifications
| Specification | Value |
|---|---|
| Sensor Type | Passive |
| Sensing Element | 20K Thermistor |
| Output | Resistance |
| Wiring | NTC, 2 wire |
| Accuracy (Standard) | ±0.36°F (±0.2°C) |
| Optional High Accuracy | ±0.18°F (±0.1°C), [XP] option |
| Stability | < 0.036°F/Year (< 0.02°C/Year) |
| Temperature Drift | < 0.02°C per year |
| Heat Dissipation | 2.7 mW/°C |
| Probe Range | -40 to 221°F (-40 to 105°C) |
| Probe | Vented polycarbonate shield, 1/2 in. OD |
| Probe Length | 1.2 in. with 1/2 in. NPT threads |
| Lead Wire | 22 AWG stranded, Etched Teflon, plenum rated |
| Termination | Terminal Strip |
| Enclosure | BAPI-Box 2 (BB2) |
| Enclosure Rating | NEMA 4, IP66 |
| Enclosure Material | UV-resistant polycarbonate, UL94V-0 |
| Enclosure Entries | Two 1/2 in. NPSM plus three 1/2 in. drillable ports |
| Enclosure Dimensions | 4.91 in. (124.8 mm) H x 2.82 in. (71.6 mm) W x 2.35 in. (59.7 mm) D |
| Vented Sensor Guard | 2.10 in. (53.3 mm) |
| Enclosure Ambient | -40 to 185°F (-40 to 85°C) |
| Enclosure Humidity | 0 to 100% RH, non-condensing |
| Wall Gasket | Closed cell foam, impervious to mold |
| Agency | RoHS; CE (passive thermistors 20K-ohm and smaller) |
Documentation
Outside Air Units Datasheet (B50-B51)Outside_Air_temp_NoPrice-v17.pdf — Rev. 10/05/23- Outside Air Temperature Sensors Installation & Operations20909_ins_OSA_Passive.pdf — rev. 02/10/21
Related Products
BAPI BA/20K-O-BB2 - 20K Thermistor Outside Air Temperature SensorBAPI BA/1.8K-O-BB2 - 1.8K Thermistor Outside Air Temperature SensorBAPI BA/1.8K-O-BB2-TB - 1.8K Thermistor Outside Air Temperature Sensor with Test and Balance Switch
Frequently Asked Questions
Where should this outside air sensor be mounted?
Mount in the shade, away from building windows, doors or vents. A sensor in direct sunlight can read higher than actual by as much as +30%. The ideal shaded location is the north side of the building in the northern hemisphere, and the south side in the southern hemisphere. Point the shield and probe down, at least four feet above the ground or roof and a minimum of one foot below the eave.
What signal does it send to the controller?
It is a passive sensor. The 20K thermistor element presents a resistance that the controller reads on an analog input, with no polarity. BAPI specifies ±0.36°F (±0.2°C) accuracy.
What wiring does BAPI recommend?
Twisted pair, at least 22 AWG, with sealant-filled connectors. Do not run this device in the same conduit as high or low voltage AC power wiring. BAPI testing shows inaccurate signal levels are possible when AC power shares the conduit. All wiring must comply with the National Electric Code (NEC) and local codes.
How much temperature can the probe take?
BAPI rates the probe for -40 to 221°F (-40 to 105°C). The BAPI-Box 2 enclosure is rated for an ambient of -40 to 185°F (-40 to 85°C) at 0 to 100% RH, non-condensing.
How protected is the BAPI-Box 2 enclosure?
It carries NEMA 4, IP66 and is made of uv-resistant polycarbonate, ul94v-0. Entries are two 1/2 in. npsm plus three 1/2 in. drillable ports, and a closed cell foam gasket seals it to the wall.
What does the terminal strip option add?
The -TS option adds a terminal strip inside the enclosure so field wiring lands on screw terminals instead of being spliced to the factory leadwires.
5 Year Warranty — Building Automation Products, Inc. (BAPI) covers this product for 5 years. Warranty service is handled through ZOT Supply as an authorized BAPI distributor.
- Product Type:
- Temperature Sensor
- Sensing Element:
- 20K Thermistor
- Output Signal:
- Resistance
- Application:
- Outside Air
- Enclosure:
- BAPI-Box 2
- NEMA Rating:
- NEMA 4
- IP Rating:
- IP66
- Termination:
- Terminal Strip
- Accuracy:
- ±0.36°F
- Probe Range:
- -40 to 221°F
- Warranty:
- 5 Year
