FireAngel HT-630 Heat Alarm

The FireAngel HT-630 is a battery-powered heat alarm built for the rooms where a smoke alarm would keep going off: kitchens, garages and unconverted lofts. It listens for heat rather than smoke, sounds at 85 decibels at 3 metres, and runs on a sealed lithium battery that lasts the life of the unit¹. It is also discontinued. FireAngel now directs owners of an HT-630 to the FireAngel FA6720-R Heat Alarm as the replacement².

If you already have one on the ceiling, the practical answer is simple: keep testing it monthly, vacuum it every three months, and replace it when it starts chirping continuously, because that means it has reached the end of its life³. If you are buying for a kitchen now, the HT-630 is no longer the model to look for.

For a household getting ready for power cuts, storms and other disruptions, a heat alarm earns its place because it keeps working when the mains does not. It has no wiring to fail and no battery to remember. What it cannot do is warn you early enough to escape from a bedroom or a hallway, and it cannot be linked to the rest of your alarms. Both limits matter when you plan a route out of the house.

The HT-630 is discontinued: what to do with an end-of-life alarm

FireAngel's product page for the HT-630 now carries the replacement instruction directly: "Replace your end of life HT-630 alarm with a FireAngel FA6720-R Heat Alarm with 10 year sealed for life battery"². The same wording appears across FireAngel's support answers, with the added reason that the FA6720-R alerts you to fires "without the false reactions to cooking fumes"⁷.

The trigger for replacement is the sound, not the calendar. FireAngel states that if your HT-630 is chirping continuously, it has reached end of life and should be replaced with the FA6720-R⁹. A single chirp every 45 seconds with a flashing yellow light is a different signal: that is the low battery warning, and the manual says to replace the unit within 30 days³. Because the battery is sealed, there is no cell to swap, so a low battery warning on this model is effectively an end-of-life warning with a deadline attached.

That deadline is worth writing down. Thirty days is short enough to forget, and a heat alarm that has stopped working gives no sign of it. Put the date in a diary or on the fridge, and treat the alarm as out of service from that point.

For the wider question of when any alarm should be retired, FireAngel notes that it designs smoke, heat and carbon monoxide alarms with 10-year lifespans¹⁰. Our guide to when to replace a smoke, heat or CO alarm sets out the general rules, and the FireAngel brand page lists the current range.

What the HT-630 does: a Class A1 fixed-point heat alarm with Thermistek detection

A heat alarm is a different instrument from a smoke alarm, and understanding the difference tells you whether it suits your household. The HT-630 is a fixed-point heat alarm, Class A1, with an alarm point temperature of 56°C to 64°C³. It uses a thermistor heat sensing element, which FireAngel describes as being for accuracy, reliability and stability, and Thermistek technology that activates the alarm sooner if it predicts a significant rate of rise in temperature³. In plain terms, it responds both to a room getting very hot and to a fire heating the room quickly.

The datasheet describes the sensor as Thermistek Class A1 heat detection, incorporating a unique radiant heat dish¹. FireAngel developed the Thermistek heat alarm, in its own words, "to give a rapid alert to danger"².

What it does for a household in an emergency is narrow but valuable. It covers the rooms where a fire is most likely to start and where a smoke alarm would be a nuisance: FireAngel says heat alarms are ideal for kitchens, garages or unconverted lofts⁸, and its product page names the kitchen, attic or garage as the places it keeps you alerted². In a power cut, it keeps watching those rooms when mains-powered equipment is dead.

What it does not do is detect smouldering fires or slow smoke, because it is not looking for smoke at all. That is why it belongs alongside smoke alarms, not instead of them.

Specifications: 85 decibel sounder and sealed 10-year battery

The figures below are the ones that decide whether the alarm suits a room and how you keep it ready.

Two of these rows bear directly on emergency planning. The operating temperature range of +4°C to +38°C means the alarm is specified for normal indoor conditions, so an unheated garage in a hard frost or a loft that bakes in summer sits outside what the maker states¹. If your garage is your chosen location, that is worth knowing before you rely on it there through a cold snap. The sealed battery is the other: it removes the commonest cause of a dead alarm, a cell that was never replaced, but it also means the whole unit is a consumable with a fixed life.

Where a heat alarm must not replace a smoke alarm

This is the safety point that matters most, and every official and maker source in this area agrees on it. FireAngel's manual states: "Heat alarms should not be installed in escape routes instead of smoke alarms"³. Its guidance for battery-powered heat alarms says they "should not be used in escape routes instead of smoke alarms"¹¹, and its guidance for mains-powered heat alarms says the same⁹.

The reason is in what the device senses. Heat alarms are designed for rooms where smoke may not be a reliable indicator of fire, such as kitchens, garages and utility rooms where fumes may create false alarms¹⁰. A hallway or landing needs to raise the alarm while a fire is still small and the route is clear. A heat alarm waiting for 56°C will not do that in time.

Scotland's official guidance goes further and sets the standard for kitchens. The Tolerable Standard guidance cites BS 5839-6:2019, Clause 12.2(f), which states that only heat alarms should be used in kitchens, while an existing smoke alarm in a kitchen need not be replaced until the end of its manufacturer's recommended lifespan¹². The same guidance requires all smoke and heat alarms to be interlinked¹². That last requirement is one the HT-630 cannot meet, because it cannot be interlinked at all.

For the full picture of which device goes in which room, see Heat Alarm or Smoke Alarm: Which Goes Where and Heat Alarms: What They Do and Where They Go.

Fitting the alarm to its ceiling base plate

Fitting is a screwdriver job, done on a ceiling. FireAngel's manual for the HT-630 sets out the sequence: "Fit the base plate to the ceiling using the screws provided", then position the alarm on the plate and turn clockwise until it is locked into position³. The general battery-powered heat alarm guidance is the same: fit the mounting plate to the ceiling using the screws provided¹¹.

The step people get wrong is the last quarter turn. FireAngel's guidance on its push-fit base is explicit that when fixing an alarm to the baseplate, "it's important to turn it as far as possible to ensure it is engaged and secure", and that a snug baseplate needs extra force⁵. Fire service advice gives the same point from the other side: if the alarm has a base plate, ensure that the unit is attached firmly to the baseplate¹⁴.

You will know it has worked. The manual says the red LED on the front of the alarm should flash once, approximately every 45 seconds to show that it is active³. If that light is not flashing, the alarm is not properly seated.

A few practical points for a household plan:

• Fit it before you need it, not during a storm warning, so you are not up a ladder in bad conditions.
• Check the seating after any decorating or loft work, since a knocked alarm can sit loose.
• Do not remove the alarm from its base to silence it. FireAngel warns that removing the alarm from its base plate will deactivate the unit and prevent it from detecting a fire¹¹.

What the red and amber lights and chirps mean

The HT-630 communicates almost entirely through one light and one sounder, so learning the code saves a lot of guesswork. The manual describes an operating red LED that flashes once approximately every 45 seconds, and a fault indication where the amber LED flashes to show a low battery condition or alarm fault³.

FireAngel's wider alarm guidance uses a similar language across its range: one chirp with a red flash every 40 to 60 seconds means low battery, and on a sealed-battery model that means replacing the alarm rather than the battery¹⁵. An amber LED flashing, sometimes with a chirp on mains alarms, means the alarm is not fitted to the base plate correctly¹⁷. If your alarm is beeping and you are not sure which of these you are hearing, our guide to why a smoke alarm keeps chirping walks through the possibilities.

The most important line in the manual is about doubt. In its own words: "IF THERE IS ANY QUESTION AS TO THE CAUSE OF THE ALARM, ALWAYS ASSUME THAT THIS IS AN ACTUAL FIRE AND FOLLOW YOUR FIRE EMERGENCY PLANS"³. A heat alarm in a kitchen can be triggered by a hot oven door or a pan left on, but the cost of being wrong in the other direction is far higher. Get out, and call the fire and rescue service.

Monthly testing, three-monthly vacuuming and safe disposal

Keeping the HT-630 ready is a two-part routine, and both parts are quick.

Testing. The manual says to test your heat alarm every month³. FireAngel's support guidance for heat alarms recommends testing weekly to be most safe, and at least once a month to be sure¹⁸. The HT-630 has a quiet test: press the test/hush button once for a self-test at reduced volume, at least 10dB below the full alarm, or double-press for the full-volume 85dB test⁵. The quiet option is useful if there are sleeping children or a shift worker in the house, but run the full test sometimes so you know the sounder really works.

Cleaning. The manual says to vacuum every three months to help keep the unit working efficiently, vacuuming the exterior and keeping the vacuum from touching the unit³. FireAngel's support article gives the same interval, every 3 months or more often if suitable¹⁹. Dust and cooking grease are the enemies of a heat sensor, and a kitchen alarm collects both.

Disposal. The HT-630 is a sealed unit, and the manual is clear that you must never attempt to open or damage the battery³. Once the alarm is removed from the base plate the internal battery is deactivated, and the unit is ready for disposal³. Waste electrical products should not go in the household bin; the alarm is ideally suited for disposal within the waste electronic and electrical equipment (WEEE) recycling scheme³. Most council tips accept small electrical items, and many retailers take them back in store.

Support, warranty and getting help

The HT-630 carries a 5 year warranty, according to both the datasheet and the manual, with the manual specifying 5 years from the date of purchase¹. The manual adds a condition that matters if you sell the house or inherit an alarm with a new home: the warranty applies to the original retail purchaser from the date of original retail purchase and is not transferable³. FireAngel's general guidance notes that warranty periods on smoke and heat alarms are usually between 3 and 5 years, and advises checking the packaging and manual for current information⁸.

If you need the instructions in another form, the HT-630 manual says the user guide is also available in large text and other formats, with the number 0330 094 5830 for further information³. FireAngel's newer manuals give the email technicalsupport@fireangeltech.com and the number 0800 141 2561 for the same purpose²⁰. For a household where someone is deaf or hard of hearing, a standard sounder may not be enough on its own; our guide to smoke and CO alarms for deaf and hard of hearing people covers the alternatives.

If the alarm does not sound when it is not being tested, FireAngel advises consulting the manual, because the battery could be running low or the alarm could be coming to the end of its life and need replacing²². One quirk to know before you worry: if the unit has been silenced and is in low sensitivity mode, it may not sound when tested, so wait 15 minutes and try again³.

For the wider job of getting a household ready, the Fire Safety Checklist for Your Home and How to Make a Fire Escape Plan are the natural next steps, and the Home Emergencies section covers fire, carbon monoxide, gas leaks and burst pipes together.