Replacing Nest with Aico Smoke Alarms

TLDR

• Google have EOLed Nest Protects, which is irritating when they have a finite life, and the various alarms have different expiry dates
• There isn't a direct replacement for them
• Aico is a sensible option if you want local notification to home assistant

Killed by Google

The Nest Protects are a fairly decent combined smoke alarm and Carbon Monoxide alarm. The system does a few things well

• Units look nice by Smoke Alarm standards
• Pathlight is a nice feature (Motion based lights)
• Unit to unit interlink over a propriety protocol
• App notifications for a smoke alarm
• "Heads up" at sub alarm levels of smoke, saying that there is smoke and where. Nicer than a loud beeping
• Possible to integrate with home assistant, but cloud based with higher potential for failure and latency

The nest protects were declared end of life. Unfortunately as the devices are smoke alarms they have a fixed expiry date, and they cease to work after that (Or at least complain a lot). Google have not handled the end of life particularly well, their anointed a replacement is only available in the US. This has left a lot of people looking for replacements.

My needs

I'm an owner-occupier in England, so at the time of writing there is no legal standard I need to meet. That said, I'd very much like to minimise my chances of dying in a house fire, and if early alerts allow me to safely put out a fire so much the better.

My requirements were

• UK Kitemarke
• Optical sensor
• Battery powered (No existing wiring for a smoke detector system)
• Point to Point radio interlink, all alarms go off together. My house is not massive, but the way the extensions have been built means I won't reliably hear an alarm in a different part of the house
• No requirement for home assistant to play any part in that interlinked system
• I don't really want to buy them from Amazon (concern over counterfeits)

My nice to haves were

• Integrates with home assistant, because I would prefer that the system automatically shut down likely sources of fire, stop the warm air system spreading smoke, turn on the lights to ease evacuation. Preferably locally
• Have a nice central panel, so the individual alarm can be identified and silenced by my average height wife
• (Not achieved) "heads up" notifications indicating the room

Aico

I looked at various options; I nearly went for an Aeotec Z-Wave SmokeShield module, but these mysteriously disappeared off the shelf. Aico are Irish manufactured, have a decent range of smoke and a decent wireless interconnect. To save you a little time

• The 600 series are their 10 year sealed battery units. These are available with or without RF interconnect. In practice I wanted the 650iRF/660iRF
• The 3000 series is their wired interconnect models.
• The 200 series covers Carbon Monoxide
• The 100 series is a mains powered alarm without interconnect, although you can put it on a radiolink base
• AudioLINK allows you to get diagnostics from the detector via a modem like noise
• RadioLINK is their wireless interlink protocol, 868mhz. This is what you want
• HomeLINK is their proprietary IOT gateway

Accessories

The accessories were the real draw

Ei450 RadioLINK Alarm Controller

Allows a little controller which allows for easy testing of the alarm (press to test), or if smoke is detected locate (silence interconnected alarms, leaving only the one which detected smoke) and silence false alarms without having to reach to the smoke alarm button. I've put mine at arm level in the hallway near the front door, the idea being that you've already proved your escape route before you start faffing around with smoke alarms I don't love that this has a sealed battery with an expiry, it feels wasteful

Ei428 RadioLINK Relay Module

This is the fun bit. Intended for strobe lights for the deaf, the unit is mains powered and flips a relay when it receives word of smoke over the RadioLINK. Hack in a cheap ESP to check the state of the relay, and you've got an easy loosely coupled local integration to home assistant.

Carbon Monoxide

Don't forget the Nest Protect offer carbon monoxide detection, but few smoke detectors include this function. I moved to a standalone CO detector as there is only once potential CO source in the house, and I plan to remove it in the near future.

Purchase

I bought the smoke alarms themselves (650iRF fit my needs) from ElectricPoint, a UK electrical wholesaler. They were the cheapest reputable source, and they arrived quickly and well packaged. The stock was fresh, Feb-2037 expiry on an April-26 purchase.

While I wasn't prepared to compromise on supply chain for the alarms, the accessories were 1/5th of the price on eBay, and as these aren't safety critical I was OK with the cheaper option.

Install

The instructions to "house code" the alarms were clear and worked fine. Some new wall plugs were needed, other than that no drama.

Hacking the relay module

I popped the case off a Sonoff Mini and was able to fit the two boards in the one housing. The relay board has two live and two neutrals, I wired a 13a plug to the relay board, and then from the second inputs on the relay board. I wired the Mini switch sensor to the NC side of the relay. The aim is that it should be detected if a connector fails.

The Sonoff Mini is pretty cheap, and flashes to ESPHome pretty nicely

ESPHome

Some snipets of the ESPHome config

  device_name: fire-sensor

esphome:
  name: ${device_name}

#Sonoff Mini
esp8266:
  board: esp8285

binary_sensor:
  # the 13 lines below notify home assistant of a change of switch sensor
  - platform: gpio
    name: fire_sensor_relay
    # Listing the switch state so that other devices can be changed based on main switch
    # internal: true  # hides relay toggle from HomeAssistant
    pin: GPIO04
    id: gpio_light_id
    filters:
      - invert:

  # the 2 lines below create a status entity in HomeAssistant.
  - platform: status
    name: ${device_name} Status```

## Home Assistant automation
Once adopted, the ESPHome pops a smoke sensor. I've added the following in home assistant
- A test switch helper, disabling the full automation. A timer fires to turn the switch back to "alarm" after 10 minutes
- An automation for the sensor switching to "smoke", which sends out a notification, turns on the lights and turn off fans
- An automation to send me a notification if the ESP goes offline