The ESi ESRTP4RFW is a wireless RF programmable room thermostat that combines time and temperature control in a single battery-powered unit, paired with a mains-wired RF receiver. Its large backlit LCD screen and simple button layout make programming straightforward, while energy-saving features such as Chronoproportional Control (TPI), Optimum Start, and Optimum Stop help reduce fuel costs and carbon emissions.
Because the thermostat and receiver communicate wirelessly, the ESRTP4RFW can be positioned in the ideal room location for accurate temperature sensing without running a control cable back to the boiler or heating zone, and can be upgraded to smart control via the optional ESWIFIHUB and ESi Centro app.
7/5-2/24h
Programming Modes
4 or 6
Daily Time/Temp Events
Approx. 30m
RF Transmission Range
5-35°C
Temperature Adjustment Range
±0.5°C
Sensor Accuracy at 20°C
6(2)A
Receiver Contact Rating
Installation requirement: The RF receiver must be installed by a suitably qualified person in accordance with the latest IEE Wiring Regulations (BS 7671) and Part P of the Building Regulations. Always isolate the mains supply before fitting the back plate or carrying out any wiring work, as live and neutral contacts may touch during mounting and damage the product or cause harm if the supply is not isolated.
Battery type: The thermostat unit runs on 2 x 1.5V AA (LR6) batteries. Do not mix old and new batteries, and do not use rechargeable batteries, as this can cause inconsistent operation or incorrect time/date resets.
Chronoproportional Control (TPI)
TPI acts as a load compensator, firing the boiler at regular intervals and adjusting the ON duration to match heat output with the building's heat loss. This reduces boiler cycling and the net return water temperature, improving efficiency by up to 10% in fuel cost and carbon emissions versus simple ON/OFF thermostats.
Optimum Start & Optimum Stop
Optimum Start automatically calculates the ideal heating start time based on current building temperature so the home reaches the desired temperature exactly when needed, rather than the user guessing a fixed start time. Optimum Stop turns the boiler off slightly early once the target is met, saving energy without a perceptible loss of comfort.
Wireless RF Pairing
The thermostat communicates with its RF receiver over an RF handshake approximately every 50 seconds, with a transmission range of around 30m in open terrain, giving flexibility in thermostat placement away from the receiver and boiler.
Smart-Ready via ESWIFIHUB
The ESRTP4RFW can be RF-paired with the optional ESWIFIHUB, unlocking remote scheduling and control through the ESi Centro smartphone app, allowing an upgrade path to smart heating control without replacing the thermostat itself.
Landlord Service Reminder
Built-in software reminds occupants when an annual Gas Safety Inspection or service is due, displaying a SER warning up to 30 days ahead of the due date, with configurable options that can also restrict heating run-time once the due date has passed.
Flexible Programming Structure
Choose between 7-Day, 5/2-Day, or 24-Hour programming, each supporting 4 or 6 temperature events per day, with a factory pre-set profile suitable for most households from first power-up.
| Programmable Room Thermostat |
| Programming Modes |
7 Day, 5/2 Day & 24Hr |
| Power Supply |
2 x 1.5V AA (LR6) batteries |
| Temperature Sensor Accuracy |
±0.5°C at 20°C |
| Temperature Adjustment Range |
5°C to 35°C |
| Number of Programs |
4 or 6 (default: 4) |
| Protection Rating |
IP30 |
| Dimensions |
127mm (L) x 81mm (W) x 28mm (D) |
| BST/GMT Time Change |
Automatic |
| Casing Material |
Thermoplastic, flame retardant |
| RF Receiver |
| Power Supply |
230VAC, 50Hz |
| Power Consumption |
6W |
| Contact Type |
6(2)A 230VAC SPDT volt-free changeover |
| Transmission Distance |
Approx. 30m in open terrain |
| Protection Rating |
IP30 |
| Dimensions |
135mm (L) x 90mm (W) x 33mm (D) |
| Fixing |
Easy-fit back plate |
| OpenTherm (Where Fitted) |
| Connections |
Polarity free |
| Maximum Line Length |
50 metres |
| Maximum Cable Resistance |
2.5 Ohms |
| Compliance |
| CE Directives |
EN60730-1, EN60730-2.7, EMC 2014/30/EU, LVD 2014/35/EU |
| UKCA Directives |
EMC Regulations 2016, Electrical Equipment (Safety) Regulations 2016 |
Do I need to pair the thermostat and RF receiver myself?
If supplied together as a kit, the ESRTP4RFW and its RF receiver are already paired at the factory and require no further pairing. If the bond is ever lost, re-pairing is done by holding the HEATING button on the receiver until the MANUAL OVERRIDE light flashes, then setting the thermostat to OFF and holding the ALL DAY, HOLIDAY, and + buttons until pairing completes.
How many temperature events can I set per day?
The thermostat defaults to 4 daily programs but can be switched to 6 daily programs via the technical settings menu, giving up to six separate time and temperature changes each day.
Can the ESRTP4RFW be used with smart home control?
Yes. It can be RF-paired with the optional ESWIFIHUB accessory, after which it can be controlled remotely using the ESi Centro app, available on the Apple App Store and Google Play.
What type of batteries does the thermostat use?
It uses 2 x 1.5V AA (LR6) batteries. Rechargeable batteries should not be used, and old and new batteries should never be mixed in the same unit.
Is the RF receiver suitable for DIY installation?
No. The RF receiver operates on 230VAC mains and must be installed by a suitably qualified person in accordance with BS 7671 (IEE Wiring Regulations) and Part P of the Building Regulations. The mains supply must be isolated before fitting the back plate or wiring the unit.
Does the thermostat support both gas and oil boilers?
Yes. The TPI setting is configurable between a 3-cycle mode (one cycle every 20 minutes, recommended for oil boilers) and a 6-cycle mode (one cycle every 10 minutes, recommended for gas boilers), allowing the control strategy to be matched to the boiler type on site.
