Heiman HS1SA-M Smoke Alarm

A small smoke alarm at a sensible price

Heiman HS1SA-M has a straightforward appeal: it puts a smoke alarm and a Matter-over-Thread connection into a 60 mm footprint without charging a huge premium for the radio. It is a good candidate for a small room in a European home that already uses Thread, particularly if a broad white disc would look intrusive on the ceiling.

Smartdomo listed it in stock for €31.95 including German VAT on September 10, 2026. One costs €36.94 delivered within Germany; two total €63.90 and pass the shop's free-shipping threshold. That makes expanding coverage less expensive than buying a premium connected alarm for every room.

Miniature in width, not in depth

The cylindrical case is 49.2 mm deep, so it still projects visibly from the ceiling. Its band of mesh also gives it more of a sensor-like appearance than a smooth, flat disc. The small footprint is attractive, but do not buy it expecting it to disappear against the plaster.

Inside is a photoelectric smoke alarm with a replaceable CR123A battery and a sounder specified at 85 dB at three metres. Heiman's declaration explicitly includes HS1SA-M under EN 14604. It is a smoke alarm rather than a combined smoke/CO device; the small body does not hide a second type of protection.

The manual and current manufacturer table estimate five years from the Matter model's battery. The retailer still says three, so a guaranteed five-year interval would be the wrong promise. The useful point is that the cell is replaceable. You must still remove the alarm to change it and maintain the smoke chamber as the manual requires.

The siren experiments are not the reason to buy it

HS1SA-M has Works with Home Assistant certification, making it a credible way to bring smoke status into an existing local system. Connected reporting requires a Matter controller and Thread border router. The alarm's own sounder remains a local function, independent of that connection.

A more eye-catching retailer demonstration uses the alarm as a remotely controlled siren. There is a catch: Smartdomo's current instructions put that capability on an optional beta firmware branch with additional Home Assistant requirements. The retailer also says that branch cannot be rolled back to the regular release.

I would judge the product on its normal smoke-alarm function, not buy a safety device around an experimental secondary use. A controllable siren is also not evidence that several alarms automatically form an interlinked smoke-alarm system. That distinction is easy to miss when the demo simply shows another alarm sounding.

Spend more for interlink, or keep things simple

Sensereo MS-1 Interlink is the more relevant alternative when you want compatible alarms on the same Thread network to sound together. Sensereo explicitly builds that behaviour into the Interlink model and lists it at $59.99 before destination-specific charges. It is considerably wider at 110 mm, and it still needs the Thread network for interlinking. The ordinary MS-1 is not interchangeable with it.

Choose HS1SA-M for compact, reasonably priced smoke reporting into a system you already own. Choose a dedicated interlinked solution when whole-home audible warning is the deciding feature. If your existing alarms are suitable, working and within their replacement dates, keep them when their only missing feature is a dashboard tile; replacing a coordinated system with separate smart alarms would be a poor trade.