Honeywell Smart Thermostats T6, T9 & Evohome Review

Honeywell has been making heating controls for decades, and their smart thermostat range reflects that heritage. Rather than flashy features for their own sake, Honeywell focuses on reliability, compatibility with UK boilers, and precise temperature control.

For UK homes with combi boilers, the Honeywell range — from the T6 to the T9 and Evohome — covers everything from simple scheduling to full, professional-grade multi-zone heating.

This guide walks through the Honeywell smart thermostat range first, then compares them to alternatives like Nest and Tado at the end for context.

Honeywell’s Smart Thermostat Philosophy (Why They Feel Different)

Honeywell designs thermostats around a simple idea

Predictable control beats clever automation when it comes to heating comfort.

Instead of relying heavily on AI learning, most Honeywell systems prioritise:

• Stable temperature control

• Accurate sensors

• Clear schedules

• Strong boiler modulation (especially with OpenTherm)

That makes them particularly well-suited to UK combi boilers, where smooth modulation and consistent flow temperatures matter more than aggressive on/off cycling.

Honeywell T6 / T6R: The Everyday Smart Thermostat

The Honeywell T6 (and wireless T6R) is the most common entry point into Honeywell’s smart ecosystem for UK homes.

What It’s Designed For

The T6 is built for households with fairly regular routines who want better control than a basic programmer, without handing decisions over to an algorithm.

It delivers:

• 7-day programmable schedules

• Geofencing to reduce heating when the house is empty

• Optimum Start (heats early so rooms reach temperature on time, not late)

• Excellent OpenTherm boiler modulation

There’s no learning behaviour — which many users see as a benefit rather than a limitation.

Real-World Performance

In practice, the T6:

• Keeps temperatures stable

• Avoids overshooting and boiler short-cycling

• Typically saves 10–15% compared with manual or basic digital controls

That’s around £100–£150 per year in a typical UK home upgrading from a simple timer.

Best Suited To

• Combi boiler homes

• Budget-conscious upgrades

• People who like predictable schedules

• Landlords and rental properties

Honeywell T9: When One Room Is Always Colder Than the Others

The Honeywell T9 builds on the T6 by introducing remote room sensors.

Instead of relying on one thermostat location, the T9 can:

• Sense temperature in multiple rooms

• Prioritise the coldest space

• Balance heating more evenly across the home

This makes a real difference in UK houses where:

• Bedrooms are colder than living areas

• Extensions heat differently

• Upstairs and downstairs behave inconsistently

T6 vs T9 in Simple Terms

If your home heats evenly already, the T6 is usually enough.
If one room dictates comfort for the whole house, the T9 is worth the step up.

Honeywell Evohome: Full Smart Zoning (The Heavyweight Option)

**Honeywell Evohome sits in a different class entirely.

Rather than controlling the boiler as one zone, Evohome creates independent heating zones for each room using wireless radiator controllers — no rewiring required.

What Evohome Does Differently

• Each radiator becomes its own thermostat

• Rooms follow independent schedules

• Boiler output is matched to real, room-by-room demand

This is the most precise way to control heating in larger UK homes.

Typical Installation Process (UK)

1. Survey boiler compatibility (OpenTherm works best)

2. Install Evohome controller and boiler relay

3. Fit smart radiator heads (HR92s)

4. Configure zones and schedules

5. Commission and test

Cost Reality (2026 UK)

Savings can exceed 30% in large or poorly zoned homes, but Evohome is overkill for small properties.

Reliability & Support (Why Engineers Like Honeywell)

From an installer’s perspective, Honeywell systems are:

• Stable

• Rarely drop connection

• Consistent across firmware updates

They don’t change app layouts as often as consumer-focused brands, which reduces user confusion and callbacks.

For landlords and long-term homeowners, that reliability matters more than novelty features.

How Honeywell Compares to Nest and Tado (Quick Context)

Once you understand the Honeywell range, the alternatives make more sense.

Honeywell vs Nest

• Nest focuses on automation and learning

• Honeywell focuses on control and predictability

Nest often saves more in chaotic households.
Honeywell wins where people want consistent, explainable behaviour.

Honeywell vs Tado

• Tado excels at radiator-based zoning with smart TRVs

• Honeywell Evohome offers more precise professional zoning

• Tado suits mid-sized homes; Evohome suits large ones

Boilers2Go Verdict

If you want reliable, no-nonsense smart heating, Honeywell’s range is hard to beat.

• T6 for affordable, dependable control

• T9 for homes with uneven temperatures

• Evohome for full room-by-room precision

Nest and Tado have their place — but Honeywell remains the go-to choice when stability, boiler compatibility, and long-term performance matter more than novelty features.

If you’re unsure which Honeywell system fits your boiler and home layout, a quick compatibility check before buying saves time, money, and frustration.