A heat detector is the right alarm for a garage, attic, workshop or shed because it senses rising temperature instead of smoke particles. Dust, sawdust, humidity and insects trigger smoke alarms constantly in those spaces, so the correct fix is to change the sensor type. This guide covers the 12 best heat detectors for attics and garages in 2026, sorted by how well each one handles heat, dust and real installation conditions.
I have spent enough summers in garage ceilings to know that the two decisions that matter are detection technology and ambient temperature rating. Pick a fixed-temperature unit rated too low for a Phoenix garage and it will either nuisance-alarm all summer or fail outright. Pick a smoke alarm instead of a heat alarm and you will be hushing it every time you turn the sanding disc on.
If your smoke alarms are already inside the living space and you want to see how those compare to a smart unit with phone alerts, read our smart smoke detector guide. For the rest of this article, the focus stays on the spaces where smoke detection does not belong: the garage, the attic, the workshop and the utility room.
| Product | Specifications | Action |
|---|---|---|
| Kidde HD135F Hardwired Heat Detector |
|
Check Latest Price |
| Kidde HD135F Compact Hardwired Alarm |
|
Check Latest Price |
| First Alert HD6135FB Ionization Heat Alarm |
|
Check Latest Price |
 System Sensor 5601P Mechanical Heat Detector |
|
Check Latest Price |
 System Sensor 5604 194F Heat Sensor |
|
Check Latest Price |
 System Sensor 5602 Dual Detection Unit |
|
Check Latest Price |
 System Sensor 5621 Fixed Rate Sensor |
|
Check Latest Price |
 Edwards Signaling 284B-PL Heat Detector |
|
Check Latest Price |
 Thermotech 302-EPM-194 Rate Compensation Unit |
|
Check Latest Price |
 Silent Knight IDP-Heat-IV Addressable Detector |
|
Check Latest Price |
 Kidde Smoke CO and Heat Bundle |
|
Check Latest Price |
 ScanaTemp AI Thermal Flame Detector |
|
Check Latest Price |
Alarms above 135F
85 dB siren
120V hardwired with 9V backup
Interconnects up to 18 Kidde devices
This is the unit I recommend first because it is the only pick here with both a deep review history and whole-system flexibility. Owners mount it in a standard ceiling box, link it to the rest of a Kidde system, and use the Test-Hush button to settle a nuisance alarm without pulling the unit down.
The trigger is a fixed 135F, far above any normal room temperature and well below the level that damages structure. The 85-decibel siren carries into a hallway. What you give up is speed, because a fixed-temperature device waits until the air reaches its number rather than responding to how fast things are heating.
Installation needs a 120V circuit run and a back box, and some owners mention wanting a professional for the wiring. The quick-connect power harness shortens the wiring side once the box is in place.
Because it stays on 120V even if the 9V backup dies, it suits a detached shop or a rental where nobody is there to hear a low-battery chirp in winter.
The strongest word in the review history is reliability at 135F. Owners running a two-car space with a vehicle, a fuel can and a water heater report stable behaviour through seasonal swings, and interconnection means one head can join eighteen other Kidde devices including smoke and CO units.
For a detached shop or a rental property, staying on 120V even when the 9V backup is dead is a real advantage over a battery-only alarm.
If your garage regularly sits above 135F for days, this is the wrong unit. The Thermotech 302-EPM-194 later in this list carries a stated -40F to 150F operating range and a 194F activation point, which is what a genuinely hot attic or furnace room needs.
It is also the wrong choice if you rent and cannot cut a circuit, since a unit with no wiring is far easier to place and to move when you leave.
135F fixed temperature
Hardwire interconnectable
Photoelectric sensor
Compact body
Half of what makes this worth a look is what limits it: buyers mostly describe it as a direct replacement for aging Kidde units on existing wiring. If you inherited a house with two-decade-old hardwired alarms, this fits the existing bracket and wiring pattern.
Technically it is a 135F fixed-temperature unit with a photoelectric sensor, corded electric power and interconnection to other Kidde devices. The photoelectric sensor is not chasing flame chemistry, which suits a garage where nothing should produce a false fast-flame signature.
Buy it if you are replacing an existing Kidde hardwired heat alarm and want the smallest profile that clears a joist or a conduit run. Owners replacing decade-old units report a quick swap with no wiring changes. Skip it for a fresh install, because the full-size HD135F has a much larger review base behind the same 135F threshold.
One reviewer flagged that it protrudes from the ceiling more than expected, leaving the silver mount visible. Factor that in before ordering a visible finished ceiling.
Verify your existing alarms sit on a 120V interconnectable line. This unit cannot be added to a battery-only or wireless setup, and it will not join a non-Kidde ecosystem.
Ionization heat sensor
Hardwired with battery backup
Model HD6135FB
Audible alarm
This is the pick when the fire you worry about starts fast rather than slow. An ionization sensor reacts quickly to the heat signature of a rapidly developing fire, which is what a garage holding a vehicle, fuel cans and a solvent shelf can become in seconds.
It is hardwired with a battery backup, so plan for a circuit run. In return you get continuous monitoring that survives a power interruption, which matters more in a detached structure than in a room with a person in it.
Ionization detection makes sense where ignition sources are liquid or chemical and the fire can develop fast. A woodworking shop full of solvent and finishing products fits that description better than a garage full of cardboard does.
It also suits anyone already running ionization smoke alarms elsewhere in the house and wanting one consistent technology to reason about.
The common complaint attached to ionization units is sensitivity to cooking steam and aerosol mist carried in on a connected door. In a dusty workshop with an open door to the kitchen, that can mean an alarm you learn to ignore.
The rating also rests on a modest number of reviews, so treat the 4.5 stars as encouraging rather than settled. The System Sensor 5601P below has a much deeper pattern of garage and utility-room use behind the same 4.6.
135F rate-of-rise and fixed temperature
Single-circuit mechanical
Reversible bracket
Fits most back boxes
This is the one I keep coming back to for anyone who wants real rate-of-rise behaviour without moving into a full fire alarm system. Most consumer heat alarms are fixed-temperature only. This one carries both detection types in a single mechanical device, and mechanical means it does not care about dust, humidity or insects the way an optical chamber does.
It is also easy to mount. The reversible bracket and supported back boxes cover single gang, 3.5 inch and 4 inch octagonal and 4 inch square, so it will fit whatever you already have in an attic or garage ceiling instead of forcing a rewiring job.
Experienced forum users repeatedly describe rate-of-rise as the correct technology for workshops and boiler rooms rather than fixed temperature. It alarms on how fast the air is heating, so a slow seasonal change in an attic does nothing while a real fire accelerates.
That is why this device pairs a 135F fixed ceiling with rate-of-rise behaviour, catching both a fast developing fire and a space that simply sits too hot for long.
There is no test button, and several owners raise that as a real drawback because you have no quick way to confirm the device is still alive.
It is single-circuit with terminal screws and no wireless capability, so plan on wiring it to a relay module, a fire alarm control panel, or a home automation system that accepts a hardwired contact. If you want phone alerts, this is not that platform.
194F fixed temperature
Single-circuit operation
White housing
Corded electric power
The whole reason this unit exists is temperature. A 194F activation point means a furnace room, a boiler closet or an unvented attic that regularly sits well above 100F will not set it off, which removes the most common complaint we heard from people trying to use 135F units in a hot garage.
It shares the 5600 series platform with the 5601P, so the mounting logic, the single-circuit wiring and the white housing will feel familiar if you have worked with commercial detection.
Choose this when ambient heat is the dominant problem rather than an afterthought. Attics in a hot climate, mechanical rooms and spaces above a furnace are the classic cases, and forum discussion on garage builds repeatedly identifies the ambient ceiling as the hard dealbreaker that rules out popular wireless models.
It also pairs well with a 135F rate-of-rise unit in a large space, so the fast detector catches an early fire and this one covers the hot spots.
At 194F, a slow developing fault may run a long time before the alarm triggers. That is acceptable in a space already too hot for a lower threshold, and unwise in a cool one.
Reviewers also note a portion of the ratings are 1-star, and there is no test button to confirm operation after wiring.
194F rate-of-rise and fixed temperature
Single-circuit operation
Terminal screws
Reversible mounting bracket
Take the 5601P and raise both numbers: rate-of-rise plus fixed temperature, and a 194F activation point instead of 135F. That combination is rare. Most residential heat alarms offer one detection type at one temperature, and this one gives you a fast-response element and a high ambient ceiling in the same housing.
The practical argument is coverage of two failure shapes. Rate-of-rise catches the early fire that has just started and is heating quickly, while the 194F fixed point catches a space that has been slowly cooking. One device covers both, which halves the number of heads you mount in a large shop.
The 5600 series also supports single and dual circuit configurations, so this platform can grow into a small multi-point system rather than staying a one-off.
If you need a unit you can confirm works with a test button, this platform does not offer one. That is a real gap for a DIY install where verification matters.
Availability is thinner than for the residential Kidde and First Alert units, so plan your purchase around the 5600 series rather than the specific model number.
Plus or minus 1.5 percent accuracy
32 to 135F measuring range
Surface mount
Push-pull output
This one is different enough to be worth understanding before you buy it. It is not an alarm. It is a precision temperature sensor with a push-pull output that reports the ambient temperature in its space to a fire alarm control panel, and the panel decides what to do with the reading.
For most homeowners that is overkill. For anyone building a monitored garage system with a panel, it is the missing piece, because it lets you log and alarm on actual temperature rather than a fixed threshold.
Think instrumentation rather than life safety. A monitored commercial garage, a battery storage room, a workshop where you want a temperature trend recorded rather than a single alarm event. It is also surface mount, so you can add it to a wall or ceiling you already finished without cutting a box.
Confirm your control panel accepts a push-pull output. Without compatible panel hardware the device does nothing at all, and if you want an alarm people hear in the garage you need a separate sounding device on the panel loop. The 5601P and 5602 are the picks for that job.
194F fixed temperature
Commercial grade construction
Made in USA
Corded electric power
The Edwards name is the reason to consider this one. It is a commercial fire equipment brand with a listed 194F fixed-temperature head, manufactured in the United States, which matters if you are working on a structure where listed commercial equipment is required rather than merely preferred.
Mechanically it is straightforward: a surface-mounted square housing with corded electric power and a single fixed activation point. There is no wireless, no app and no rate-of-rise element to consider.
There are properties and jurisdictions where a residential alarm will not satisfy an inspector or a landlord obligation. A commercial listed head from an established manufacturer is the defensible answer when the space is a workshop with a business operating out of it, or part of a larger rental portfolio. The 194F threshold also makes it a natural fit above mechanical equipment, where a 135F head would sit permanently near its trigger.
Reviewers are split. A meaningful share of the ratings are 1-star, which reads as quality control inconsistency rather than a design flaw, and the total count is small enough that neither side settles the question. Buy it from a channel that handles commercial parts so a failed unit is easy to replace, and check with your authority having jurisdiction before relying on a single head.
Rate compensation detection
194F activation
1600 sq ft coverage
-40F to 150F operating range
This is the unit to look at when ambient temperature is the hardest constraint in the room. The stated operating range runs from -40F to 150F, the widest span in this roundup, so the device itself is not the limiting factor in a space that swings hard between winter and summer.
Detection is rate compensation rather than plain rate-of-rise. In plain terms it responds to the rate of temperature change, so a slow seasonal drift inside that wide range does not trip it while a genuine fire still gets flagged.
At 1600 square feet, this is the only pick here designed for a single head to cover a genuinely large bay, workshop floor or open-plan mechanical space. That changes the install math if you were pricing three or four separate points. UL and CSFM listing and US manufacture make it the most defensible spec sheet in the group for anyone who has to show a code body what they installed.
Two reviews, both five stars, is not a reliability record. Both reviewers note the same thing the spec sheet does, which is that you are paying for the build and the range, not a proven field history.
Because it is a surface mount device on a commercial platform, confirm your panel or relay arrangement accepts its output before committing to a single-head layout.
Addressable IDP protocol
135F fixed temperature
Reports exact location to panel
Requires compatible control panel
Addressable detection solves a specific problem: when an alarm sounds on a large loop, the panel tells the crew exactly which device triggered. On a site with a workshop, a storage barn and an office in one building, knowing which bay is burning in the first thirty seconds is worth real money, and that is the entire value of this device.
The rest of the specification is deliberately ordinary: a 135F fixed thermal detector on an IDP protocol loop, powered by the panel, reporting to a Silent Knight control panel.
If you already run a Silent Knight IDP fire alarm system, or you are building one for a commercial property, an addressable head is the natural choice because it drops into the existing point naming scheme and shows up as its own zone at the panel. For a homeowner with no panel, it does nothing, since there is no local siren path here and no standalone function.
The 135F activation point is the wrong number for a garage that runs very hot, the same ambient ceiling issue we flagged at the start. Pair it with a 194F head like the Thermotech unit if the space runs hot, rather than relying on one head type for every room.
Note also that the rating rests on a very small review base, because this is a professional installation item most residential buyers never touch.
Smoke and CO plus 135F heat sensing
10-year sealed battery
Interconnects up to 24 devices
Hardwired with backup and 85dB alarm
Some rooms need more than heat detection. A garage with a gas water heater raises a carbon monoxide question, and the door from that garage into the house raises a smoke question. This bundle answers all three hazards in one interconnected hardwired system with a 10-year sealed battery as backup.
The interconnection figure is the headline number: up to 24 devices, of which the heat alarm can act as an initiating unit. That is a much larger network than the 18-device ceiling on the standalone Kidde heat detector.
It makes sense when you are upgrading an interconnected system across a whole property rather than solving a single garage problem. A landlord fitting out a multi-unit building, or a homeowner replacing a fleet of alarms on one circuit, gets smoke, CO and heat from a single purchase. The 10-year sealed battery saves the most effort over time, because there is no annual ladder climb to swap cells in a high ceiling.
A single five-star review is not a track record, and the unit carries more hardware than a heat-only alarm needs in a space where the goal is simply to hear about a smoldering fire early.
If your requirement is strictly heat detection in one garage, the standalone hardwired heat alarm at number one does the same job with a much deeper review history behind it.
AI thermal and visible imaging
Built-in sound monitor
WiFi alerts with screenshots
AC power with backup battery
This one watches a different failure mode. The other eleven products answer the question of when a space becomes dangerously hot. This one is aimed at lithium battery thermal runaway, the failure that matters if you charge an e-bike, a scooter or a vehicle indoors overnight, because it can move from first heat to flash fire faster than a fixed-temperature head can report.
It uses a thermal imager alongside a visible imager, so it can identify a flame signature and a hot spot rather than a single threshold crossing. Owners cite the screenshots, the pre-alarm image, ten seconds of captured audio and a marked map of the warmest points in view as the features that actually help them respond.
The sound monitor is the underrated part. If a battery pack vents or an adjacent device goes off, the unit hears it and reports while the heat signature is still developing. Notifications go out by WiFi over SMTP or MQTT, and there is integration with security platforms alongside a phone app.
Charge zones. A wall beside an EV charger, an e-bike storage wall, a room with a portable solar and battery bank. In those spots an imager that shows a rising hotspot before anything smokes is more useful than a number crossing 135F. It runs on AC power with a backup battery, so a wall outlet is fine.
Be clear about what this is. It is a monitoring and notification device, not a listed heat detector, and a local sounding alarm in the garage is still something you need separately. It also needs WiFi and app setup, so it is wrong for an unconnected shed, and its small review count means the long-term field record is still being written.
Rate-of-rise heat detectors. These alarm when the air temperature climbs quickly, typically a set number of degrees per minute. They ignore normal daily and seasonal swings and react early to a fire that is actively developing, which makes them the strongest choice for workshops and utility rooms.
Fixed temperature heat detectors. These sit dormant until the air around the sensor reaches a preset point, most often 135F or 194F. They are simple and very reliable, and the trigger number is what you match to your space’s normal ambient temperature.
Combination smoke and heat alarms. These add an optical chamber to a heat element so they can catch both a fast flaming fire and a slow smolder. They belong inside the living space, not in a dusty garage, because the smoke chamber is the part that nuisance-alarms there.
Most residential heat alarms sold for garages are type two. The rate-of-rise options we reviewed sit in the commercial System Sensor line, which is why they pair naturally with a panel or a relay module rather than a consumer interconnect wire.
A fixed temperature detector answers the question has this room become too hot. A rate-of-rise detector answers the question is this room heating unusually fast. In a space that cycles between 40F overnight and 115F on a summer afternoon, only the second question is informative, which is why experienced builders on garage forums keep recommending rate-of-rise for shops.
The practical compromise many land on is a device that does both. The System Sensor 5601P pairs 135F fixed temperature with rate-of-rise at a price that suits a single-room install, and the 5602 does the same at 194F for a hotter space. The one case where fixed temperature alone makes sense is a space already near its trigger, since nobody installs a 135F head in a furnace room that idles at 150F.
This is the check most shoppers skip and most buyers regret. A heat alarm has a stated operating temperature range, and exceeding it is not a small matter, because the sensing element is calibrated for a specific band. Forum discussion on garage builds treats the ambient ceiling as the first question to ask, ahead of brand or price.
A Phoenix user describing a garage that sits above 115F in summer rules out a whole class of device outright. If your space runs hot, you need a 194F trigger or a wide stated range, which is why we included the Thermotech 302-EPM-194 with its -40F to 150F specification. Add a second consideration for attics: solar gain on an unshaded roof deck pushes the space well past what a sheltered garage ever sees, so measure the real peak before choosing.
Hardwired units, like the Kidde HD135F and the First Alert HD6135FB, are the most robust option where you can run a circuit. They do not stop monitoring when a cell dies, they are the normal choice for an interconnected system, and they are what most inspectors expect.
Sealed 10-year battery units remove maintenance entirely, and the printed end-of-life date tells you when to replace the device. That matters most in a high ceiling where a yearly battery swap means a ladder.
Replaceable-alkaline models are cheapest to buy and most annoying to own, because the low-battery chirp happens in the middle of the night. One clarification on the list we reviewed: none of these twelve are sealed-battery standalone models, so the available options here skew hardwired and commercial.
This is the most-asked question in garage and low-voltage forums and almost no roundup answers it. There are four real routes.
Wireless interconnection within one brand. You buy heat alarms that can radio-link to each other and to that brand’s smoke alarms. Fastest install by far, no wiring, but it only works inside a single manufacturer’s ecosystem and it does not connect to a security panel.
Hardwired to a fire alarm control panel. The mechanical System Sensor devices and the addressable Silent Knight head are built for this. It is the most code-aligned route and gives you a panel that reports exactly which device triggered, but it needs a panel, wiring and usually a professional.
Relay module to a listed alarm. A hardwired heat detector drives a relay that breaks a listed smoke alarm’s loop, so activating the heat alarm pulls the house system. This is the retrofit that answers the homeowner who already has smoke alarms everywhere and just wants one heat point in the garage. Confirm your alarm manufacturer permits the connection, because some void the listing.
Wi-Fi with its own hub. A connected detector such as the ScanaTemp unit reports to an app and to your phone by itself. It needs no panel, but it is not a listed heat alarm and phone alerts do not substitute for a local siren inside the garage.
Whichever route you take, remember that most jurisdictions still expect a code-listed local alarm sound in the space itself. A notification on your phone is a supplement, not a replacement, for an 85 dB siren in the garage.
Ceiling, not wall. Heat rises and spreads along the ceiling, so the ceiling is where the sensor sees a fire first. Wall mounting works only if it is on the upper third of the wall.
Centre of the ceiling, away from corners. Corners and the junction of wall and ceiling trap dead air. Stay clear of the corners by a foot or more.
Keep it off the garage door opener. A door opener motor assembly and its rails sit in the path of rising heat and can also mask it. Treat the whole opener as a keep-out volume.
Clear of furnace, water heater and dryer. Any heat source within a few feet will either nuisance-trip the alarm or desensitize it. This is the most common placement mistake we see.
Away from supply registers, air returns and exterior doors. Fast-moving air carries heat away from the sensor and delays or prevents a rate-of-rise alarm.
On the ceiling of the room the garage door is in when you have a workshop bay, because that is where a fire actually develops.
For an attic, mount on the ceiling if the attic is conditioned or partially finished, and mount on the floor deck or a joist if the space is fully open framing and unconditioned. In an uninhabited attic with HVAC equipment, the heat detector covers the equipment; the smoke alarm belongs inside the living space near the attic access door rather than out in the deck.
Dust and sawdust. Optical chambers load up in a workshop and start reporting smoke that is not there. This is exactly the failure that pushes woodworkers to heat alarms in the first place, and it is a reason to keep the sensor clean.
Insects and spiders. Small insects nest inside the sensing chamber and trigger nuisance alarms, a complaint that repeats across forum accounts of garage installations. Screen the chamber where the model allows it and inspect it twice a year.
Humidity swings. A rapid change in humidity at a garage door or an unconditioned wall can trip a sensor. Stabilising the ambient conditions helps more than chasing the alarm.
Temperature swings that are real. A seasonally warm attic will push a fixed 135F unit over its trigger. The answer is the correct trigger number, not a hush button.
A heat source too close. A dryer, furnace or water heater within a few feet is the fastest route to a nuisance alarm. Relocate the device before you assume the device is faulty.
The consequence of ignoring a recurring false alarm is worse than the alarm itself. People report pulling hardwired units offline entirely after repeated dispatches, which leaves the space unprotected and, on some monitoring plans, on the hook for a response fee. Fix the placement or the device, but do not stop listening.
Look for the word. Heat alarms are usually labelled HEAT or include a model number ending in a heat designation. Smoke alarms say SMOKE or SMOKE ALARM.
Read the label on the back. Most units print the sensing type and the activation temperature. A temperature number printed on the label means heat detection.
Check for a test button and hush button. Both types have them, so this alone does not distinguish anything.
Feel the vents. A smoke alarm has a clear chamber with visible slots or mesh and often a small light sensor window. A heat alarm has a smaller metal or sealed sensing element with far fewer openings.
Look at the model number. Model strings containing HD or a degree marking are heat alarms; model strings beginning with SM are smoke alarms.
Either way, a quick press of the test button on a monthly walk is the cheapest verification available, and it is the one habit that catches a failed sensor before it matters.
Requirements vary by jurisdiction. Residential codes commonly require smoke and CO alarms inside living areas and allow a heat alarm in attached garages because smoke alarms nuisance-alarm in dust and humidity. Uninhabited attics housing HVAC equipment are one of the cases where a heat alarm is commonly called for rather than a smoke alarm. Always check your local authority having jurisdiction, because a landlord or insurance requirement can be stricter than the base code.
The three main types are rate-of-rise detectors, which alarm when temperature climbs quickly; fixed temperature detectors, which alarm at a preset point such as 135F or 194F; and combination smoke and heat alarms, which add an optical chamber so they catch both fast flaming fires and slow smolders. Garages and attics need the first two, because the smoke chamber in a combination alarm is the part that false-alarms in dusty spaces.
Mount it on the ceiling, in the centre of the room and away from corners. Keep it clear of the garage door opener assembly, furnaces, water heaters and dryers, and away from supply registers and exterior doors where moving air will hide a rising temperature. Treat the door opener and its rails as a keep-out volume because the motor housing can mask a developing fire.
It depends entirely on the unit. A 135F fixed-temperature alarm in a space that regularly sits above 100F will nuisance-alarm, and a unit whose stated operating range does not include your peak temperature can be damaged. Choose a 194F trigger for a hot attic or furnace room, or a device with a wide stated range such as -40F to 150F. Measure the actual peak before you buy rather than estimating from your weather.
One properly placed head covers a typical single-bay garage or workshop bay. Larger spaces with an open floor plan need more, spaced so no point on the ceiling sits more than about 20 feet from a detector and none falls in a corner. A vehicle bay and a separate workshop bay each need their own. Use a higher-threshold unit on spaces that run hot so you are not relying on one device type everywhere.
The usual causes are dust or sawdust loading the sensing chamber, insects nesting inside it, rapid humidity swings at an open garage door, a heat source such as a dryer or furnace within a few feet, or ambient temperature genuinely crossing the trigger point. Fix placement and clean or screen the chamber twice a year. Do not simply disconnect a recurring alarm, because that leaves the space unprotected and can trigger monitoring fees.
Yes, through a relay module. A hardwired heat detector drives a relay that breaks the loop of a listed smoke alarm, so activating the heat alarm activates the house system. Confirm with your smoke alarm manufacturer first, because some listings are voided by an unlisted connection. Wireless interconnection is simpler but works only inside one manufacturer’s ecosystem. Either way, most jurisdictions still expect a local sounding alarm in the garage itself.
The Kidde HD135F hardwired heat detector takes our top spot in 2026 because it pairs the deepest review history we found with genuine interconnection to a whole alarm system, an 85 dB siren and a 9V backup that survives an outage. It suits an attached garage or a normal attic utility room where you can run a circuit.
If your space runs genuinely hot, move up the trigger number rather than fighting nuisance alarms. The Thermotech 302-EPM-194 handles a -40F to 150F ambient range from a single head with 1600 square feet of coverage, and the System Sensor 5604 and 5602 give you a 194F ceiling at a lower tier. For a workshop where early detection matters, the System Sensor 5601P adds rate-of-rise behaviour at a 135F fixed point.
Two spaces deserve separate attention. An uninhabited attic with HVAC equipment needs a heat alarm on the deck plus a smoke alarm inside the living space at the access door. And a garage used for EV or e-bike charging needs the kind of imager-based monitoring the ScanaTemp unit provides, since lithium failure outruns a fixed threshold.
While you plan the install, it is worth reading our radon detector picks if the space is below grade, and our radiant barrier insulation guide if you are addressing attic temperature in the first place, since the same summer heat driving your nuisance alarms is worth managing at the roof deck.
