Frequently Asked Questions
Built for the Field. Backed by Expertise.
Everything you need to know about the HST Series, from choosing the right model to using it safely and efficiently.
General Information
What does "HST" stand for in HST Series Heat Detector Tester?
HST stands for “Heat Stick Tester.” In the fire alarm industry, probe-style heat detectors, especially rate-compensated models, are often referred to as “heat sticks.”
Why should I choose the HST Series Heat Detector Tester over other heat detector testers?
The HST Series is designed to test probe-style (heat stick) detectors in the field. There is no need to remove them from the ceiling or wall. Compared to bench testers (which cost $7k–$10k+ and require removal/reinstallation), the HST is faster, portable, and much more cost-effective.
What makes the HST Series Heat Detector Testers better for field use?
- Portable and battery-powered
- Designed for vertical and overhead testing
- Extension poles, carry bags, and coiled cables available for a complete kit
- Built to work in high ceilings, warehouses, and industrial sites
- Reduces downtime and labor costs
Is the HST Series Heat Detector Testers approved by detector manufacturers?
The HST Series is not officially “approved” by any one brand, but many manufacturers recommend it as a safe and effective testing method. Always check the guidelines for your specific sensor.
What is the warranty on HST Series Heat Detector Testers?
Skinner Innovations offers a 1-year limited warranty against manufacturer defects. Warranty does not cover cosmetic wear, misuse, or tampering. Always contact customer support before sending in a unit for repair.
Detector Compatibility & Use
Is the HST Series Heat Detector Testers compatible with my detectors?
The HST works with most probe-style heat detectors, including popular models from Fenwal, Thermotech, and others. Fill out our request info form or email us your detector specs or photos and we’re happy to confirm compatibility or find an option for you.
Will a high-temperature HST Series tester work on all my detectors, regardless of the rated set point?
Overshooting the manufacturers rated setpoint could cause the setpoint to permanantly shift. Always consult the manufacturers test procedure to determine the max test temperature over the setpoint.
What size or temperature model do I need?
The right HST model depends on the diameter and trip point temperature of your heat detector. We offer testers for a variety of shell sizes (like 5/8″ or 17/32″) and temperature ranges.
We’re here to help you find the HST model that fits your application.
Just call, email, or submit a request form, and we’ll match you with the best test kit based on your detector specs.
How can I identify the type of and manufacturer of my heat detector?
Probe type heat sensors all look very similar. Look for Manufacturer and temperature rating on detector. Fenwal “Detect-a-Fire” uses a stainless steel shell that is 5/8 inch diameter. “Thermotech uses an aluminum shell that is 17/32 inch diameter.
For help with identification: Email: info@skinnerinnovations.com
Can I use one HST Series Heat Detector Tester for multiple detector types?
Possibly, depending on the temperature and shell size. However, using an overly hot tester on a low-temperature detector can damage or shift the setpoint. We recommend matching your HST to your exact use case.
How do I read an HST part number?
HST model numbers follow the format HST-#-###-#. “HST” designates the HST Series; the first letter shows sensor size (A=5/8″, B=9/16″, C=16mm, D=20mm); the three letters indicate temperature set points (e.g., ALO = 140–225°F, MEL = 160–275°F, AHI = 450–725°F); and the final digit identifies options. Models are designed for Fenwal® DETECT-A-FIRE® detectors (27127, 28021, 27120, 28020). Contact Skinner Innovations for other sizes, set points, or custom options.
Testing & Calibration
Does this tester replace the need for expensive calibration labs?
While not a lab calibration device, the HST Series offers functional field testing. It’s used by fire protection professionals worldwide to verify detector trip points and identify failing sensors without expensive lab work or unnecessary replacements.
How long does it take to test a detector?
Most detectors trip within 5 to 25 seconds when using the HST Series tester. However, the full test cycle may run up to 5 minutes, depending on the detector’s design, ambient temperature, and rate of heat rise.
The HST includes a built-in timer to accommodate detectors that require longer heat exposure, but most users complete testing well before the timer ends. Always follow the manufacturer’s test procedure for the specific detector you’re testing.
The HST Series supports extended heating cycles for more thorough testing, but functional verification is typically observed in the first 30 seconds of standard use.
Can I recalibrate my heat detector in the field?
No. Heat detectors are factory-calibrated and cannot be recalibrated in the field. In fact, UL-listed heat detectors are purposefully designed to prevent field recalibration, as required by testing standards.
For full calibration, detectors must be sent back to the manufacturer or tested in a lab environment under controlled conditions.
- Functionally test the detector
- Identify major shifts in the detector’s set point
Support compliance testing without damaging the device
For full calibration, detectors must be sent back to the manufacturer or tested in a lab environment under controlled conditions.
Can I use the HST Series Heat Detector Tester in hazardous environments?
The HST Series is not rated for hazardous locations. However, you can still test detectors safely:
- 1. Fully heat the tester in a safe area close to the hazardous area. You may need to set the tester to a higher temperature to achieve these steps
- 2. While still in the safe area, unplug & remove the battery from the tester
- 3. Enter the hazardous area without power to the tester and without the battery
- 4. Commence testing heat detectors, until the tester cools. You will test using residual heat
- 5. Repeat as necessary
This procedure will allow you to function test the detectors in the hazardous area.
If the exact trip point of the detectors must be verified then the hazardous area would need to be de-classified prior to testing.
Do I need accessories to use the tester?
You can operate it as a standalone unit, or attach it to your own compatible extension pole, but for high or hard-to-reach detectors, we recommend adding:
What multimeters are compatible with the output cable?
Most standard volt-ohm meters (VOMs) or digital multimeters with 0.75″ (19 mm) banana jack spacing.
Battery & Accessories
My battery didn't last as long as expected, why?
The two biggest factors that affect battery runtime are:
- Temperature set point – Higher heat settings require more energy to maintain
Other factors that may reduce runtime include ambient temperature, battery age or condition, and starting with a partial charge.
Why shouldn’t I let my HST battery fully discharge before storing it?
HST battery packs contain built-in monitoring circuitry that protects the internal lithium cells. If any cell drops below a critical voltage, such as when the battery is left fully discharged, the circuitry will permanently disable charging or discharging to protect the battery. This is known as “bricking” the battery.
To extend battery life:
- Always recharge the battery before putting it into storage
- If storing long term, recharge at least once every 6 to 12 months
- Avoid storing the battery completely empty
Following these practices will help you get the best possible life and performance from your battery pack.
What safety features are built into the HST Series Heat Detector Tester and accessories?
The HST Series Heat Detector Tester test head and battery pack are designed with safety and durability in mind for field use:
The Battery Pack includes built-in circuit protection for:
- Over-current
- Over-charge cut-off
- Over-discharge
- Short circuit and reverse polarity
The HST Test Head has an automatic timeout function to prevent overheating if left on too long
LED indicators guide operation and error states
When used with optional accessories, additional safety protections include (see accessories for details):
- Rubber strap attachments (included with extension and output cables) prevent cables from pulling on connectors and falling during elevated testing
- Bayonet-locking cable connectors, rated for 300+ connection cycles (included with extension and output cables)
- Fanless design on the stand-alone power supply, which uses passive cooling and reduces mechanical failure risk
Note: Always follow the recommended cable attachment procedure and operating conditions listed in your manual for safe use of accessories.
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