What you need to know before choosing a thermostat
Checklist: Clarify These Points Before You Buy
- →Check voltage of existing system: 230V (standard) or 24V safety extra-low voltage (bathrooms, wet rooms)
- →Determine the number of heating circuits — each room with a separate heating circuit requires its own thermostat
- →Clarify mounting location: flush-mounted (concealed) or surface-mounted, is there a wall opening for cables?
- →Wi-Fi router or ZigBee gateway within range? (ZigBee EGATE-PRO max. 1 m from the router)
- →Smart home system available (Alexa, Google Home, Apple HomeKit)? Check compatibility.
Wired, WiFi, or ZigBee – A Comparison of Systems
The choice of thermostat determines the reliability, comfort, and energy efficiency of the entire underfloor heating system. Three fundamentally different communication methods are available — each with its own cost and failure profile.
Wired — fully autonomous, no router, no gateway
ThermostatEasy-230 / ESimple
from 15 €
from 15 €
Control cable
Control boxECB8-230V
54 €
54 €
Relay output
ActuatorE30NC-230
10 € / pc
10 € / pc
Heating pipe
Heating circuit1x per room
✓ 100% offline — no internet, no cloud account, no password. Time programs are stored securely in the thermostat even during power outages.
WiFi — App control without gateway, directly via WLAN
E55 ThermostatFlush-mounted 55mm
48.69 €
48.69 €
WLAN 2.4 GHz
RouterExisting
no extra purchase
no extra purchase
Internet
Tuya Cloud(Third-party
server EU/DE)
server EU/DE)
App access
App / AlexaRemote control
Google Home
Google Home
⚠ Cloud-dependent: If the internet fails, the app is not accessible. Local operation on the thermostat and saved time programs continue to function.
ZigBee — Mesh network with local gateway, offline-safe
EONE ThermostatEONE-230V / BAT
from 64 €
from 64 €
ZigBee 3.0 Mesh
EGATE-PROGateway (one-time)
61.81 €
61.81 €
LAN cable
RouterExisting
Optional
App / AlexaRemote control
Google Home
Google Home
✓ Time programs locally in EGATE-PRO — continue to run if the internet fails. Mesh automatically routes around dead spots. Up to 50 devices per gateway.
Protocols in direct comparison: 12 criteria
| Criterion | Wired | WiFi | ZigBee |
|---|---|---|---|
| Thermostat price | from 15 € | from 49 € | from 64 € |
| Additional costs (Gateway) | No | No | + 62 € EGATE-PRO |
| Cloud dependence | ✗ No | ○ Yes |
○ Limited App optional |
| Offline time programs | ✓ Yes |
✓ Yes local in thermostat |
✓ Yes local in gateway |
| Internet outage → heating still running? | ✓ Yes | ✓ Yes | ✓ Yes |
| Internet outage → app working? |
✗ No no app needed |
✗ No |
✓ Yes locally via Gateway |
| App remote access | ✗ No | ✓ Yes | ✓ Yes |
| Alexa / Google Home | ✗ No | ✓ Yes | ✓ Yes |
| Mesh range | Cable (unlimited) | up to ~30 m (router) | Mesh 50m+, self-healing |
| Reaction accuracy (TPI) | ±0.5 °C | ±0.2 °C | ±0.1 °C (EONE) |
| Setup effort | Low | Medium | Higher (Gateway setup) |
| Matter future (from 2026) | ✗ No | ✗ No | ○ Bridge via Thread |
| Recommended for | 1–8 rooms Budget/Simplicity |
1–4 rooms App convenience |
2–50 rooms Efficiency + Reliability |
Decision aid: Which system for whom?
You want to control 1–2 rooms, no Smart Home, budget under 60 € per zone:
Wired Easy-230 or ESimple
Weekly program, no router, 5-year warranty. No update risk, no cloud account. From 15 €.
You want to control via app, have stable WLAN and don't need a separate gateway:
WiFi E55 WiFi or E20i WiFi
Direct WLAN connection, Alexa & Google Home, no gateway purchase. From 49 €. Note Tuya cloud dependence.
3+ rooms, heat pump, maximum efficiency or offline-safe system:
ZigBee EONE-230V + EGATE-PRO
TPI ±0.1 °C, time programs local, mesh network. Gateway 62 € (one-time). Amortization < 1 heating season.
Retrofit without new control line — old building, rented apartment, no cable path possible:
ZigBee EONE-BAT or E20i WiFi (wireless)
Battery-powered, freely positionable. EONE-BAT: ZigBee Mesh, 1.5–2 years battery. E20i: Wireless transmitter + wired receiver.
Assemble thermostat, control box, and actuators to match the heating system.
To the configurator →TPI algorithm: Why standard thermostats are not enough for UFH
Underfloor heating systems react slowly — the lead time is 30 to 90 minutes, depending on the screed mass and construction. Conventional thermostats simply switch on and off (hysteresis): the room overheats, the thermostat switches off, the room cools down, the thermostat switches on again. The result is uncomfortable temperature fluctuations of ±1–2 °C.
The TPI algorithm (Time Proportional & Integral) solves this problem: Instead of hard switching, TPI modulates the on-time of the actuator proportionally to the temperature difference. With a 0.5 °C difference, the actuator runs open for only 20% of the cycle, with a 2 °C difference, 80%. The result: stable ±0.1–0.5 °C accuracy, no overshoot, up to 15% less energy consumption compared to hysteresis thermostats.
All ENGO thermostats (except ESimple) use TPI. The EONE-230V ZigBee achieves the highest precision with ±0.1 °C — especially relevant for heat pump systems, where every tenth of a degree affects the COP.
Is the upgrade worth it? Amortization & BAFA funding
A ZigBee system for 4 rooms costs around 258 € more than a wired system (451 € vs. 193 €). Is the investment worth it?
258 €Additional cost ZigBee
vs. Wired (4 rooms)
vs. Wired (4 rooms)
15–25 %Heating cost savings
through TPI + absence control
through TPI + absence control
~1 yearAmortization period
with 1,200 €/year heating costs
with 1,200 €/year heating costs
Example calculation: 4-room apartment, 1,200 €/year heating costs. ZigBee-TPI + absence reduction saves around 200–300 €/year. Additional costs 258 € ÷ 240 €/year = just over 1 heating season.
BAFA BEG EM — 15% funding for control technology
- Funding program: Federal funding for individual measures (BEG EM), application to BAFA
- Funding rate: 15% of net investment (20% with individual renovation roadmap iSFP)
- Eligible for funding: Room thermostats, control boxes, actuators, hydraulic balancing
- Apply BEFORE commissioning a craftsman — retroactive applications will be rejected
- Effect in example: 15% of 258 € = 38.70 € → real additional costs only 219 € → amortization < 1 year
GEG § 61: Individual room control as a legal obligation
GEG § 61 stipulates room-by-room temperature control for all heated rooms. In the event of a heating replacement or major renovation (windows, insulation, heating surfaces), individual room control must be retrofitted — even for existing underfloor heating systems without thermostats. The standard solution: one thermostat per heating circuit with the associated actuator at the distributor. Central control based on outside temperature alone is no longer sufficient.
All ENGO thermostats are GEG-§-61 compliant. The wired variant (Easy-230 + ECB8-230V) is the most cost-effective solution to fulfill the obligation, starting from 34 € per zone.
Price overview Thermostats & System Costs 2026
| Product / Item | Price |
|---|---|
| Wired Simple — ESimple-230 | from €15.06 |
| Wired programmable — Easy-230 | from €24.90 |
| Wi-Fi Thermostat — E55-B/W 230V | from €48.69 |
| Wireless Wi-Fi Thermostat — E901-WIFI | €92.15 |
| ZigBee Thermostat — EONE-230V (wired) | €64.09 |
| ZigBee Thermostat — EONE-BAT (battery-powered) | €67.59 |
| ZigBee Thermostat E25-230V (compact) | €48.69 |
| ZigBee 8-Zone Control Box ECB62-ZB | €95.43 |
| EGATE-PRO Gateway (for ZigBee systems) | €61.81 |
| Wired 8-Zone ECB8-230V | €54.43 |
| Actuator E30NC-230 (mandatory per zone) | €9.50 per piece |
| 1-zone base: Easy-230 + E30NC-230 | from €34.40 |
| 4-zone ZigBee system complete | approx. €320–450 |
| 4-Zone Wi-Fi System Complete | approx. €250–350 |
| Amortization of investment | in one heating season |
Frequent Questions About Underfloor Heating Thermostats
For simple single-room control without a smart home: Easy-230 (€24.90) — programmable, stable, no router needed. With remote access via app and 1 room: WLAN thermostat E55 (€48.69). For multi-zone systems with Alexa/Google and maximum reliability: ZigBee system with EONE and EGATE-PRO. ZigBee continues to work offline, WLAN systems do not.
TPI stands for Time Proportional & Integral — a control method specifically developed for slow-reacting heating systems such as underfloor heating. Instead of switching the actuator on/off, TPI modulates the ON time proportionally to the temperature difference. The result: more uniform room temperature, less overshoot, up to 15% lower energy consumption. All Engo thermostats (Easy-230, EONE, E25) use TPI.
No. Radiator thermostats switch quickly and abruptly, whereas underfloor heating systems react sluggishly (30–60 min response time). A standard thermostat overheats the room and then switches off – the result is uncomfortable temperature fluctuations. UFH thermostats like the Engo models use the TPI algorithm, which was specifically developed for this sluggishness.
4-zone wired: 4× Easy-230 (€99.60) + ECB8-230V (€54.43) + 4× E30NC-230 (€38) = approx. €192. 4-zone ZigBee: 4× EONE-230V (€256.36) + ECB62-ZB (€95.43) + EGATE-PRO (€61.81) + 4× E30NC-230 (€38) = approx. €451. According to Engo, the ZigBee surcharge (approx. €260) will pay for itself within one heating season due to up to 30% heating cost savings.
Most living areas use 230V thermostats. 24V (safety extra-low voltage) is mandatory in damp rooms such as bathrooms and showers (VDE regulation). In the bathroom, the thermostat must be installed outside the protective zone (outside zones 0–2). Engo offers control boxes compatible with both 230V and 24V (ECB8-24V).
Yes. GEG (German Buildings Energy Act) Section 61 stipulates room-by-room temperature control for all heated rooms. Existing buildings with central control must be converted to individual room control when replacing the heating system or undertaking major renovations. This also applies to underfloor heating systems. A thermostat per heating circuit with an actuator on the manifold is the standard solution.
ZigBee is more reliable: The mesh network routes around obstacles, and time programs continue to run locally on the EGATE-PRO — even if the internet fails. Wi-Fi thermostats rely on the router; if the internet goes down, app control does not work. ZigBee uses the 2.4 GHz band with its own protocol, which competes less with Wi-Fi devices.
ZigBee 3.0 is the basis for the new Matter standard (Matter 1.0+). ENGO ZigBee devices can be integrated into Matter ecosystems via a Matter bridge (e.g., Apple HomePod, Amazon Echo 4th Gen.). Matter 1.5 (2026) will also introduce energy clusters for dynamic electricity price integration (EPEX Spot). This makes ZigBee hardware a solid investment with a clear upgrade path — without needing to change devices.
Wired thermostats (Easy-230, ESimple, EONE-230V) must be electrically connected – this may only be done by a qualified electrician. Battery-operated variants (EONE-BAT) and the radio transmitter of the E20i, however, can be placed without electrical work. The control box (ECB8, ECB62-ZB) is permanently installed at the heating circuit distributor and also requires an electrician. For BAFA funding, a specialist company is mandatory anyway.
Yes. The BEG EM (Federal Funding for Individual Measures) grant program covers 15% of the cost of room thermostats, control boxes, and actuators — with no minimum investment limits for control systems. With an individual refurbishment roadmap (iSFP), the rate increases to 20%. Important: The BAFA application must be submitted BEFORE commissioning a tradesperson. A retrospective application will be rejected.
Two solutions without new wires: (1) EONE-BAT ZigBee: battery-powered thermostat, placed freely in the room, communicates via ZigBee Mesh with the ECB62-ZB receiver on the manifold. Battery life approx. 1.5–2 years. (2) E20i WiFi: wireless radio transmitter (room) + wired receiver (manifold), connected via 868 MHz radio. For the ZigBee variant, an additional EGATE-PRO gateway is required.
Yes - EONE thermostats are fully integrable via the Zigbee2MQTT adapter or ZHA (Zigbee Home Automation) in Home Assistant. The EGATE-PRO Gateway is not strictly necessary; instead, a ZigBee USB coordinator (e.g., SONOFF Zigbee 3.0 Dongle, approx. €15) is sufficient. However, this means that official ENGO app support is no longer available, and configuration requires technical expertise.
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