Rointe High Heat Retention storage heater
Rointe’s HHR (High Heat Retention) storage heaters are among the most advanced electric heating solutions available. They charge during the lowest off-peak tariffs (economy 7 & economy 10) and release heat efficiently throughout the day, reducing running costs while helping to balance demand on the electricity grid.
Off peak tarifs compatible
Save while you sleep
High Heat Retention heater
Maximum heat storage
Full control of comfort
Steady temperature
Efficient smart comfort
Inverter Smart Adaptive Tech
What is off peak heating?
Off-peak heating uses electricity during the cheapest, low-demand hours — usually overnight — and stores that energy as heat for use throughout the day. In the UK, this is typically linked to Economy 7, which offers a reduced night-time rate and a higher daytime rate.
By charging during these low-cost hours, off-peak heaters can cut running costs while keeping your home warm all day. It’s an efficient way to take advantage of low-demand electricity, reduce pressure on the grid and improve overall energy efficiency.
What is high heat retention (HHR)?
- More stored heat, less waste.
- All-day comfort, even during peak hours.
- Greater efficiency from every off-peak charge.
How do storage heaters work?
- They charge at night during off-peak hours.
- They store the heat thanks to strong insulation.
- They release it when needed.
Exceptional Heat Retention
Onyx offers unparalleled heat retention, storing warmth deeply and releasing it slowly over time. Rather than cooling down quickly, it keeps rooms comfortable for longer and reduces the need for constant reheating — delivering steady comfort with greater efficiency.
With this superior heat-storage performance, Onyx retains more of the heat it absorbs, wasting less energy and maintaining comfort for up to 16 hours after charging. Instead of overheating in the morning and cooling too quickly in the afternoon, the warmth is released steadily and predictably throughout the entire day.
Precise control
Visual display
Smart charge function
Save in every charge
Fully programmable
Heating that hits your lifestyle
Advance & Boost functions
Always ready to heat
Smart Charging That Actually Works
Smart Charging allows the Onyx storage heater to charge more intelligently instead of simply heating for the entire off-peak period. With this mode activated, the heater uses an advanced algorithm to calculate how much heat it needs for the next day and when it should start charging to reach that level on time. Watch the video to learn more.
WHY DOES THIS MATTER?
Because no storage heater can retain heat 100%. The longer it holds the stored heat, the more is naturally lost. By charging later — only when necessary — Onyx minimises heat loss and reduces unnecessary energy use.
Smart Charging means the heater never charges more than needed, never charges earlier than necessary, and always aims to reduce heat loss and improve efficiency — automatically.
TOP FEATURES
INVERTER SMART ADAPTIVE
Our most advanced low-consumption technology. Onyx’s Inverter Smart Adaptive system adjusts performance intelligently to deliver steady, comfortable heat while keeping energy use to a minimum.
WIFI DIRECT
An integrated WiFi module built directly into our connected heating products, enabling seamless data transmission and smart control, without the need for external gateways or extra hardware.
IA HEATING SYSTEM
The Advanced Artificial Intelligence heating system learns from your habits and room conditions, recommending smarter settings that enhance comfort while optimising energy consumption.
MINERAL CORE TECH
Its internal energy cells are engineered with a special magnetite alloy designed to store and retain up to 6% more heat per unit, ensuring a steady, comfortable heat release long after charging has finished.
LIMITED MODE
Limited Mode narrows the selectable temperature range and restricts certain functions, allowing only controlled adjustments within preset limits. Perfect for homes with children, hotels, hostels and Airbnb properties.
SMART CHARGE
Smart Charging allows Onyx to charge intelligently rather than heating through the entire off-peak period. The heater calculates how much heat it will need for the next day and charges only what’s necessary, at the right time.
BOOST MODE
Boost Mode increases the temperature to a selected level for a defined period, providing rapid, focused heat when needed. Once the boost time ends, the heater automatically returns to its normal settings for efficient operation.
ADVANCE MODE
Advance Mode allows you to activate the next scheduled heating period instantly. If you arrive home earlier than planned, simply press the Advance button and the heater switches to the upcoming comfort temperature without waiting.
Heating that adapts to your life
With ONYX, you’re not limited to a few fixed schedules. The heater offers four pre-programmed modes designed for the most common daily routines, plus a fully custom 24/7 schedule where you can define every hour of the week exactly as you want. You stay in full control — deciding when, how and how much your heater warms your home, for comfort that truly fits your lifestyle.
Automate your heating system for greater comfort and savings
Looking for smart WiFi heating that really is? Unlike many systems that require expensive adapters purchased separately, the Rointe WiFi Direct system connects your radiators, towel rails, storage heaters, water heaters and thermostats directly to the router.
Forget about configuring gateways, smartboxes or extra modules.
Connect your devices with the Rointe Nexa app and start managing your heating system from anywhere. Adjust temperatures, program as you wish, control consumption, block devices and create automatic scenarios according to your location.
Smart Heating Starts with
ONYX + Rointe Nexa
Looking for smart WiFi heating that really is? Unlike many systems that require expensive adapters purchased separately, the Rointe WiFi Direct system connects your radiators, towel rails, storage heaters, water heaters and thermostats directly to the router.
Forget about configuring gateways, smartboxes or extra modules.
Connect your devices with the Rointe Nexa app and start managing your heating system from anywhere. Adjust temperatures, program as you wish, control consumption, block devices and create automatic scenarios according to your location.
Temperature control
You can adjust the temperature or check the current room temperature so you always stay in control.
Scheduling at your fingertips
View or edit your charging or heating schedule.
Advance/Boost
Activate the Advance or Boost mode easily with just one click.
Quick access to your modes
Select Eco, Comfort, Anti-Frost or turn the product off with a single tap.
WHERE ONYX WORKS BEST
Residential Refurbishment & Home Upgrades
In renovation and home improvement projects, high heat-retention storage heaters such as Rointe’s ONYX deliver an immediate upgrade in efficiency, comfort and control. They are ideal for replacing older systems without complex building work, making use of cheaper night-time tariffs to charge and providing stable warmth throughout the day. With Smart Charging, ONYX adjusts the required energy based on the home’s actual usage, avoiding overcharging and reducing running costs. In addition, WiFi Direct allows the heating to be managed from a smartphone, bringing convenience and modernisation to any refurbished home.
Social Housing & Housing Associations
High heat-retention storage heaters, such as Rointe’s ONYX, offer an ideal solution for social housing in the UK. They take advantage of cheaper night-time electricity, store heat efficiently and release it steadily throughout the day, reducing costs and improving comfort. Their 60% heat retention and Smart Charging system optimise energy use and help improve EPC ratings. In addition, their WiFi Direct connectivity enables remote control and minimises maintenance, providing long-term reliability and efficiency for both housing providers and residents.
Educational Buildings
In educational centres, high heat-retention storage heaters such as Rointe’s ONYX provide precise thermal control tailored to fixed schedules. Their ability to deliver steady, consistent heat during teaching hours ensures comfortable classrooms without temperature fluctuations, even in the coldest months. Smart Charging automatically adjusts the charge according to expected usage, avoiding unnecessary consumption at weekends or during non-teaching periods. In addition, WiFi Direct connectivity enables centralised management, ideal for maintenance teams who need to supervise multiple spaces from a single point.
Holiday Lets & Short-Term Rentals
In holiday homes and short-term rentals, high heat-retention storage heaters like Rointe’s ONYX offer a key advantage: stable comfort without constant switching on and off. Their ability to charge overnight and retain heat for up to 16 hours prevents unexpected consumption between guest stays and reduces the energy spikes typically caused when guests arrive and turn the heating up to maximum. Thanks to Smart Charging and WiFi Direct connectivity, property owners can control the system remotely, adjust schedules according to bookings and ensure a pleasant environment from the very first minute — all with far greater energy efficiency.
ONYX HELP YOUR EPC RATING
Modern high-heat-retention storage heaters like Onyx improve EPC performance because they charge mainly during off-peak hours, using electricity with a lower carbon factor and primary energy demand.
Their efficient heat retention reduces the need for daytime top-ups, while smart controls (timers, thermostatic regulation, open-window detection and zoning) further support SAP calculations and meet Lot 20 requirements. Classified as smart storage heaters, they receive more favourable EPC assumptions than older direct-acting systems, helping many properties move from an E to a C or even B rating and supporting Future Homes Standard and Net Zero targets.
ONYX HELP YOUR EPC RATING
Modern high-heat-retention storage heaters like Onyx improve EPC performance because they charge mainly during off-peak hours, using electricity with a lower carbon factor and primary energy demand.
Their efficient heat retention reduces the need for daytime top-ups, while smart controls (timers, thermostatic regulation, open-window detection and zoning) further support SAP calculations and meet Lot 20 requirements. Classified as smart storage heaters, they receive more favourable EPC assumptions than older direct-acting systems, helping many properties move from an E to a C or even B rating and supporting Future Homes Standard and Net Zero targets.
The Ultimate Heating Combo: Onyx with Rointe Radiators
A single heating product can improve efficiency — but a coordinated system is what transforms the whole home. Rointe’s ecosystem allows different devices to work together for maximum comfort and energy savings.
Whole-home heating balance
Onyx delivers long-lasting off-peak heat in main living areas, while Rointe radiators and towel rails efficiently support smaller rooms. This avoids oversizing, reduces wasted energy, and ensures consistent comfort across the home.
One smart system with the Rointe NEXA app
All devices — including Onyx — connect to the same platform, allowing you to schedule each room, adjust temperatures remotely, activate energy-saving modes, and track real-time consumption. A unified system eliminates the inefficiencies of mixed controls.
Adaptive performance with lower energy use
Rointe’s Smart Adaptive Technology maintains stable temperatures without constant cycling. Combined with Onyx’s high heat retention, the system provides steady warmth with significantly reduced energy waste.
Comfort when you need it, savings when you don’t
Onyx covers the base load, while radiators and towel rails provide quick support in specific areas. This minimises peak-time energy use and keeps every room warm only when needed.
Future-proof efficiency and compliance
All Rointe products meet Lot 20 requirements and include advanced energy-saving features. Using them together ensures full-home efficiency, improved EPC performance, and long-term reliability.
The result: A smarter, more efficient home
Pairing the Onyx High Heat Retention Storage Heater with other Rointe smart products creates a fully optimised heating system that:
Maximises off-peak energy
Minimises consumption
Keeps temperatures stable
Improves EPC scores
Gives you full control
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Discover our range
Onyx Slim High Heat Retention Storage Heater with WiFi & AI
Frequently asked questions: Storage Heaters
What is a storage heater and how does the Onyx differ?
A storage heater uses cheap off-peak electricity (e.g., overnight) to “charge” a thermal core, then releases that stored heat gradually through the day. The Onyx takes this a step further by using a high-density core and advanced insulation to retain heat for up to 16 hours, giving you longer, more consistent warmth and better efficiency.
How does Onyx improve energy efficiency?
Because the Onyx holds heat longer and releases it more steadily, it needs fewer daytime top-ups and uses less peak-rate electricity. Features like smart charging algorithms, WiFi control through the Rointe NEXA app and intelligent inverter operation help minimise wastage and optimise performance.
Can Onyx work on an Economy 7 or off-peak tariff?
Yes — Onyx is designed to make the most of off-peak/two-rate tariffs (like Economy 7 in the UK). It charges during the low-cost period and stores the heat until you need it, which helps lower your running costs compared with using only daytime power.
What does “high heat retention” mean and how long does Onyx retain heat?
High heat retention means the unit can store stored energy efficiently and release it over many hours instead of losing it quickly. Onyx retains heat for up to 16 hours after charging thanks to its superior insulation and core materials — keeping rooms comfortable even later in the day.