T991A1079 Honeywell Proportional Temperature Control – 24-30VAC, 160–260°F, 20 ft Capillary
🔥 Product Overview
The T991A1079 Honeywell Proportional Temperature Control is a modulating temperature controller designed for precise control of water or air temperature in ducts, tanks, and similar applications. With a setpoint range of 160°F to 260°F, this remote bulb controller allows accurate temperature modulation for HVAC and process systems.
Application:
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Modulating control of water or air temperature in ducts, tanks, and other heating/cooling systems
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Ideal for industrial, commercial, and residential setups requiring precise temperature management
⚠️ Note: ❗ Ensure voltage compatibility before installation.
⚙️ Key Features
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✅ Modulating temperature control for water or air systems
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✅ Wide setpoint range: 160°F to 260°F
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✅ Remote copper bulb sensing element for flexible placement
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✅ 20 ft capillary tubing for extended reach
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✅ Analog output with one 135-ohm potentiometer
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✅ Fast response models for duct mounting, 4× faster than standard
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✅ Ambient temperature compensated for case and tubing
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✅ Adjustable throttling range (3°F to 30°F)
📊 Specifications
| Specification | Details |
|---|
| Part Number |
T991A1079 |
| Brand |
Honeywell |
| Type |
Proportional Temperature Control |
| Voltage |
24–30 VAC |
| Frequency |
50/60 Hz |
| Analog Output |
One 135 Ohm Potentiometer |
| Setpoint Temperature Range |
160°F to 260°F |
| Maximum Operating Temperature |
280°F |
| Throttling Range |
3°F to 30°F |
| Sensor Element |
Copper Bulb |
| Number of Sensor Inputs |
1 |
| Capillary Length |
20 ft |
| Bulb Size |
1/2" diameter × 4-3/16" long |
| Dimensions (HxWxD) |
5-5/8" × 2" × 2-1/4" |
| Color |
Gray |
| Application |
Ducts, tanks, or similar systems requiring modulating temperature control |
⚠️ Common Symptoms Indicating Replacement or Upgrade
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Inconsistent water or air temperature
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System fails to modulate properly
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Slow response to temperature changes
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Sensor damage or capillary tube leaks
❓ Frequently Asked Questions (FAQ)
Q: What is the voltage requirement for the T991A1079?
A: 24–30VAC, 50/60Hz.
Q: Can this controller be mounted remotely?
A: Yes — it comes with a 20 ft capillary tubing and copper bulb sensor.
Q: What is the temperature range?
A: Setpoint range is 160°F to 260°F with a maximum operating temperature of 280°F.
Q: Does it support fast response for duct mounting?
A: Yes — duct mounting models have coiled sensing elements that respond at least four times faster than standard models.
Q: How is the throttling range adjusted?
A: The throttling dial inside the case allows proportional throttling adjustment from 3°F to 30°F.
🛒 Shopping Tips
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Verify the system voltage and frequency before installation
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Ensure capillary tubing length meets your application needs
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Check for physical damage to the copper bulb or tubing
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Adjust the throttling range according to your specific application for precise modulation
