Key takeaways
- Smart TRVs cost £45–£70 each plus a hub (£70–£150). A 10-radiator house lands at £600–£900 total.
- Full zoned systems like Honeywell EvoHome cost £700–£1,500 for the controller plus £55–£70 per zone valve, £1,200–£2,200 for a typical install.
- Traditional motorised zone valves with a multi-channel programmer cost £400–£800 — old technology, but still works.
- Real-world energy savings are typically 8–12% for either smart approach versus single-thermostat heating, not the 30%+ some marketing claims.
- Smart TRVs are the right answer for most UK homes — they need no plumbing, work with any boiler or heat pump, and integrate with Home Assistant, Alexa, and Google Home.
- Full EvoHome makes sense in larger homes (5+ bedrooms) where you genuinely want different heating schedules in different parts of the house and integration matters.
"Heat the rooms you use, when you use them" is one of the cheapest energy efficiency upgrades available. The marketing for it has gone a bit overboard — claims of 30%+ savings are unrealistic for most households — but a properly set up zoned heating strategy genuinely saves 8–12% in a typical home, and pays for itself in 2–4 years.
The question is which approach: per-radiator smart TRVs, a full zoned system like EvoHome, or traditional motorised zone valves. Each has a different cost, different install complexity, and different real-world performance.
This article works through the three options on cost, savings, install complexity, integration, and the heat pump compatibility issue that flips the standard advice. We won't tell you smart TRVs cut your bills by a third — that's not honest. We will tell you exactly what to expect.
Three approaches explained
Smart TRVs are battery-powered valves that screw onto the existing TRV pin on each radiator. They have a temperature sensor, a small motor, and a wireless connection to a hub. You set a schedule per room from your phone. Examples: tado°, Drayton Wiser, Hive, Aqara, Shelly TRV.
Full zoned systems use a central controller (the brains) plus motorised TRVs on each radiator (the muscle). The system orchestrates the boiler, the central pump, and individual radiators in concert. Honeywell EvoHome is the dominant brand, with up to 12 zones and modulating boiler control via OpenTherm.
Traditional motorised zone valves are old-school plumbed valves on flow pipes that split your heating system into 2–4 zones (e.g. upstairs/downstairs, living/sleeping). A multi-channel programmer schedules each zone. No per-radiator control, but full plumbed isolation.
Cost comparison
| System | Headend cost | Per-radiator cost | 10-rad install |
|---|---|---|---|
| Smart TRVs (e.g. Drayton Wiser) | £100–£150 hub | £45–£60 per TRV | £600–£800 |
| Smart TRVs (premium, e.g. tado°) | £200 starter | £60–£80 per TRV | £800–£1,100 |
| Honeywell EvoHome | £700–£1,500 controller | £55–£70 per zone | £1,250–£2,200 |
| Traditional motorised valves (3 zones) | £200 programmer | £100–£200 per valve + plumbing labour | £500–£900 |
The pricing is closer than you'd think when you do a full house. Smart TRVs win on simplicity and DIY-ability — most are plug-and-play with no draining of the system. EvoHome wins on integration depth and per-radiator boiler modulation. Motorised valves win nothing on a per-feature basis in 2026 but are familiar to plumbers and bulletproof reliable.
One thing worth flagging: smart TRV pricing has bifurcated. Cheap Chinese-import models from brands like Aqara are now £30–£40 per radiator and work fine. Premium brands like tado° charge £60–£80 per radiator with no obvious functional advantage beyond a slicker app. The mid-market (Drayton Wiser, Hive) sits between the two. For a 10-radiator home the budget choice saves £400–£500 versus premium.
Real-world savings
Marketing claims need to be read carefully. tado° and Hive both publish "up to 31%" savings figures. These are based on best-case scenarios where the alternative is a single thermostat in the hallway running the whole house at 21°C all day. Most UK homes already have programmer schedules and have learned not to leave heating on full whack — so the realistic uplift from zoning is much smaller.
Independent studies (Energy Saving Trust, BRE) typically show:
- Smart TRVs vs single-room thermostat: 8–12% saving in a typical home
- Full zoning (TRV or EvoHome) vs no scheduling at all: 15–20% saving
- Smart vs traditional TRVs (manual): 3–6% additional saving from learning behaviours and presence detection
For a £1,200/year heating bill, that's £100–£140/year savings. On a £700 install (smart TRVs), that's a 5–7 year payback. On a £1,700 install (EvoHome), it's an 11–14 year payback on energy alone — though EvoHome users tend to value the system for the comfort and control, not just the bill cut.
The biggest single saving comes from the simplest behavioural change: not heating bedrooms during the day and not heating the lounge while you're at work. If your existing setup already does this with a basic programmer plus manual TRVs, the smart upgrade only adds learning, presence detection, and convenience — the underlying scheduling discipline you already had. If your existing setup runs the whole house at 21°C from morning to night, smart TRVs can save much more, because you're starting from a worse baseline.
| System | Annual saving | Payback (years) | 10-year net benefit |
|---|---|---|---|
| Smart TRVs (10 rads) | £100–£140 | 5–8 | £300–£700 |
| EvoHome (10 zones) | £120–£160 | 11–14 | -£100 to £100 |
| Motorised zones (2 zones) | £60–£90 | 8–11 | £0–£200 |
Install complexity
Smart TRVs: If your radiators already have TRV bodies (most post-1990s rads do), you unscrew the manual head, screw on the smart head, and pair it to the hub. No water drained, no plumber needed. Total time per radiator: 5–10 minutes. If your radiators have lockshield-only valves (no TRV body), you need a plumber to fit TRV bodies first — about £40–£80 per radiator including parts.
EvoHome: Plumber recommended even for the swap-out parts because the system controller wires into your boiler. Day-and-a-half typical install, and the system needs commissioning per zone (room calibration runs for 24–48 hours after install).
Motorised zone valves: Always plumber territory. Pipe work needs cutting, valves need fitting, heating system drained and refilled, programmer wired into boiler. Two days typical for a 3-zone install.
Heat pump compatibility
Heat pumps work best with steady, low-flow-temperature operation across the whole house. Aggressive zoning fights this — if you turn off bedroom radiators during the day, the heat pump sees a smaller emitter surface, raises flow temperature to compensate, and SCOP drops. The heat pump installation industry typically advises:
- Limit zones to no more than 2–3 (e.g. living vs sleeping vs spare)
- Avoid TRV-based zoning altogether and use one weather-compensated controller
- If using TRVs, set them as upper limits not active controls (i.e. all set to 22°C, not all set to varying schedules)
This is the opposite of the smart-TRV-everywhere mantra. If you're heading toward a heat pump, install a single smart thermostat with weather compensation, and use TRVs only for occasional room-level overrides.
The exception is high-thermal-mass underfloor heating with a heat pump, where zoning is fine because the floor stays warm even when active heating is off in a zone. For radiator-based heat pump systems, the simplest control strategy nearly always outperforms aggressive zoning.
Where each system shines
Smart TRVs win when:
- You want to start small and add rooms over time
- You're a renter (no permanent plumbing, easy to remove)
- You're staying on a gas boiler for the foreseeable future
- You want Home Assistant / smart home integration
- Your usage pattern varies a lot (home office one room, kids' bedrooms different schedule)
EvoHome wins when:
- You have a large house with genuinely different occupied zones
- Boiler modulation matters (compatible with OpenTherm boilers)
- You want one integrated system rather than per-room batteries
- You'll keep gas heating for the long term
Motorised valves still win when:
- You have a 2-zone simple split (upstairs/downstairs) and no need for per-room control
- You don't trust internet-dependent products
- You want zero ongoing battery replacement
Integration angle
If you already use Home Assistant, Apple HomeKit, Google Home, or Alexa, smart TRV integration depth varies massively:
- tado°: Works with all four ecosystems. API access (paid).
- Drayton Wiser: Local API, excellent Home Assistant integration. Cloud-optional.
- Aqara: Zigbee — fully local, works with any Zigbee hub including Home Assistant.
- Shelly TRV: WiFi-based, MQTT, fully local.
- Hive: Cloud-only, limited integration.
- EvoHome: Cloud API only, no local control.
For Home Assistant users, Wiser or Aqara are the strongest picks. For Apple users without HA, tado°. For people who don't care about integration and just want a working app, Hive is fine.
One trap to flag: cloud-only systems (Hive, EvoHome to a degree) leave you stranded if the manufacturer pulls the cloud. There have been multiple cases over the last decade of smart home brands shutting down servers and bricking customer hardware. Local-control brands (Wiser, Aqara, Shelly) protect against this risk. If long-term resilience matters to you, prioritise local control over flashier features.
FAQ
Do smart TRVs work with combi boilers?
Yes, but with a caveat. Combi boilers don't have a system pump that runs continuously, so when all TRVs close down the boiler may short-cycle. Most smart TRV hubs include a load-compensation logic that keeps at least one zone open to avoid this. EvoHome handles it via its boiler-relay control.
What's the battery life on smart TRVs?
Typically 18–24 months on AA batteries. Premium units (tado°, Drayton) tend to land at 24 months; budget units around 12–18. Replacement is a 2-minute job per radiator.
Can I mix brands?
Mostly no within a single system. Each brand uses its own hub. You can run two systems in parallel (e.g. Drayton Wiser for most rooms, an Aqara on a single radiator) but you lose central scheduling.
Do I lose hot water control?
No — most smart TRV hubs and EvoHome both include hot water schedule channels for system boilers. Combis don't have a cylinder so this doesn't apply.
What about underfloor heating?
Wet UFH uses manifolds with electric actuators, not radiators. EvoHome supports UFH actuators directly. Smart TRVs don't — you'd need a different solution (Heatmiser, Warmup) for UFH zones.
Will my plumber install smart TRVs?
Most will, though some grumble that they "don't need a plumber." Honest plumbers will tell you that's true — these are DIY-friendly. If your plumber insists on a £200 install fee, find a different one.
What this means for your decision
For most UK households in 2026, smart TRVs from a reputable brand (Drayton Wiser, tado°, Aqara) are the right answer. Cheap to start, easy to expand, no plumber needed, payback under 8 years. EvoHome is overkill in a typical 3-bed semi but earns its premium in larger homes with genuinely separate occupancy patterns. Traditional motorised zone valves remain a workable budget choice for simple two-zone splits.
If you're heading toward a heat pump, hold off on aggressive zoning entirely — install a single weather-compensated controller and use TRVs only as upper limits, not as a way to actively turn off rooms.
Estimate the savings for your specific house with the heating controls payback calculator on EcoSavingHub — covers smart TRVs, zoned systems, and weather compensation.
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