TekOnline

How We Built a 7-Zone HVAC Controller with ESPHome

The 7-zone controller is now running, and this post walks through the build direction we took at TekOnline.

The goal was simple: create a zone control platform that is reliable, local-first, and deeply compatible with Home Assistant.

Project requirements

Before writing firmware, we locked in these constraints:

  • Run up to 7 HVAC zones
  • Integrate cleanly with Home Assistant
  • Avoid cloud lock-in
  • Keep configuration transparent and maintainable

That pushed us toward ESPHome from day one.

Why ESPHome was the right base

ESPHome gives us a declarative way to manage outputs, boot behavior, and integration with Home Assistant entities.

Benefits we are seeing:

  • Fast iteration for control logic changes
  • Predictable deployment and OTA updates
  • Clear source-controlled configuration files
  • Easy extension as requirements evolve

Control model overview

At a high level, each zone is mapped to its own output and exposed through Home Assistant.

Key implementation choices:

  • Explicit boot behavior for deterministic startup state
  • Zone-level output control that can be automated by schedules or conditions
  • Entity naming that keeps dashboards understandable at scale

This makes the system practical for both DIY operators and professional installers.

Integration lessons from real deployment work

Getting control logic right is only part of the job. Network reliability and discoverability also matter.

Important lessons:

  • Keep local network and mDNS behavior predictable
  • Document onboarding steps so replacement or migration is painless
  • Treat observability (logs, entity status, diagnostics) as a first-class feature

What comes next

With the controller now operational, the next phase is packaging and rollout:

  • Better install documentation
  • Tiered offers for DIY and installer channels
  • Case studies from early deployments

If you want updates and early access options, follow TekOnline and join the waitlist.

Build with control, not compromise

A zoning controller should not force you into vendor constraints. With ESPHome and Home Assistant, you can build a stack that remains yours as your home or client requirements grow.


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