Embedded Systems Engineer

About us

At Havenwise, we're making energy cheaper and easier for people. To do so, we’re building the hardware and software platform for home energy starting with the heating system, the single biggest energy load in most homes. We've already built and launched a software product that connects to heat pumps and cuts energy bills by ~40%. 

We're now taking it further with our own hardware products: a smart hub and thermostat. The architecture is taking shape - a hub in the home that talks to the heat pump, communicates with the cloud, and connects to a wireless thermostat - but the key technical decisions are being made now. You'll help shape them, not just implement a spec. 

With full control over the tech stack, you'll build the firmware foundation for the optimisation logic for electrified homes that measurably reduces energy bills. We're backed by fantastic investors via a recent pre-seed round, and have a strong network of installers to bring the new products to market in the next 12 months.

Your role

You'll be our first embedded engineer, owning the firmware and hardware integration across two physical products: a mains-powered hub and a battery-powered wireless thermostat.

You'll work directly with the CTO and a small team of engineers. This is a high-ownership role where your work ships to real homes.

Your responsibilities

• Own the full embedded stack: firmware architecture, hardware module selection, connectivity, and device lifecycle (provisioning, OTA, secure boot, watchdog).
• Build the communication layer between the controller and heat pump and between the controller and cloud (Modbus RTU, MQTT).
• Design and implement the wireless link between hub and thermostat, optimising for battery life (12+ month target).
• Implement the thermostat screen UI in an embedded graphics framework. V1 is minimal - status, setpoint, boost - but it must look good, not just work.
• Build robust offline behaviour: the hub continues operating when internet drops.
• Build safety limits into the firmware so the device stays within safe operational boundaries at all times.
• Select and integrate off-the-shelf compute modules, radios, and transceivers.

What we're looking for

• You've shipped a consumer product with an MCU and a screen. Show us.
• Strong C. Comfortable with LVGL or equivalent embedded graphics.
• Experience with serial protocols (Modbus, UART, SPI) and MQTT.
• Experience with OTA updates, secure boot, connectivity management.
• You care about what the screen looks like, not just whether it compiles.
• Comfortable in a small team where you own the full embedded vertical.

Nice-to-haves

• BLE, Zigbee, or Thread experience
• Low-power design and battery management.
• Heat pump, HVAC, or building controls domain experience.
• CAN bus (future battery/solar/EV integration).
• Python (for collaborating on cloud-side tooling with the backend team).

Your benefits

• Competitive salary and options.
• London-based office. This is a hybrid role where we get to collaborate in the office 2-3 days per week. Occasional travel to pilot sites.
• Own the entire embedded stack of a physical product from day one.
• Work directly with the CTO on architecture that runs in homes for 10+ years.
• Climate tech: your firmware directly accelerates the transition to cheaper, cleaner home energy.

Your path to joining us

1. Call with Alex (CTO) - tell us what you've built.

2. Technical exercise - small embedded task.

3. Meet the full team.

4. Offer and welcome.