Knowledge base
Build your heat battery decision
Work from the job you need done to the numbers, installation and ownership questions. You do not need to read everything: start with the stage closest to your decision.
Start here
11 guidesHeat battery glossary
Plain-English definitions for kW, kWh, phase-change material, standing loss, flow temperature, tariff windows and other terms used in heat storage quotes.
Read guide →02Technology explainedCharge and discharge rates
Understand why storage capacity in kWh and power in kW answer different questions about charging time, showers and heating demand.
Read guide →03Technology explainedEfficiency and heat loss
Separate charge efficiency, standing loss and delivered useful heat so product figures can be compared on the same basis.
Read guide →04Technology explainedEnvironmental impact
Materials, manufacturing, energy source, heat loss, service life, repairability and end-of-life all shape the environmental case.
Read guide →05Battery basicsHeat battery FAQ
Short answers to the questions homeowners ask about hot water, heating, tariffs, solar, size, safety, installation and running out of stored heat.
Read guide →06Technology explainedHeat battery safety
A practical guide to temperature, pressure, electrical protection, siting, water safety and the documents a homeowner should receive.
Read guide →07Battery basicsWhich kind of battery?
Heat batteries store thermal energy; sodium-ion and solid-state batteries store electrical energy. Here is how to tell which conversation you are having.
Read guide →08Battery basicsHot water or whole-home heating?
The difference between replacing a cylinder and replacing a boiler, including demand, electrical load, controls and grant implications.
Read guide →09Understand the technologyHow heat batteries work
A heat battery stores energy as heat and releases it later for hot water or space heating. Here is what happens inside and where the energy goes.
Read guide →10Understand the technologyPhase-change materials
Why melting and solidifying can store useful heat, and which performance questions matter more than the chemistry label.
Read guide →11Battery basicsTypes of heat battery
The main ways homes store heat, what each format is suited to and why the product's job matters more than the word battery.
Read guide →Plan your system
17 guidesHeat storage in older homes
Period properties can use heat storage, but heat loss, radiator temperatures, pipework, listed status and electrical capacity need early checks.
Read guide →02Choosing and sizingHeat batteries with radiators
A whole-home heat battery must supply the right water temperature and power for long enough. Radiator sizing and building heat loss set the test.
Read guide →03Installation and supportBuilding regulations
Electrical safety, hot-water safety, energy performance and certification routes to discuss before domestic heat battery work begins.
Read guide →04Choosing and sizingControls and scheduling
Plan charge windows, boosts, tariff changes and manual overrides so the heat store is ready without buying avoidable peak electricity.
Read guide →05Installation planningElectrical supply requirements
Charging power, spare capacity, dedicated circuits, consumer units and load control explained for a domestic heat battery survey.
Read guide →06Choosing and sizingFlow rate and water pressure
Why litres per minute, pressure and temperature rise must be checked together before replacing a cylinder or combi boiler.
Read guide →07Choosing and sizingHeat batteries in flats
Compact thermal storage can suit a flat, but electrical capacity, lease terms, water pressure, access and noise from related equipment still matter.
Read guide →08Installation and supportCheck grants and VAT
Announced support is not the same as an open application route. Check the current official position before relying on a heat battery grant or VAT treatment.
Read guide →09Installation planningInstallation survey checklist
A room-by-room and service-by-service checklist for a productive heat battery survey and comparable written quotes.
Read guide →10Installation planningInstallation timeline
Plan design, permissions, supply checks, delivery, removal, installation, commissioning and the first week of monitoring.
Read guide →11InstallationPlan an installation
What to check before a heat battery survey, from electrical capacity and pipework to controls, commissioning and handover.
Read guide →12Installation and supportCompare installer quotes
Turn three different heat battery quotations into a like-for-like comparison of scope, assumptions, performance, protections and price.
Read guide →13Choosing and sizingPair with a heat pump
Storage can separate heat-pump operation from demand, but extra temperature and losses can also reduce the benefit. Start with the system purpose.
Read guide →14Solar and storagePairing with solar PV
Learn when diverting solar electricity into stored heat makes sense and what to compare with export payments, a cylinder and a home battery.
Read guide →15Installation planningReplace a cylinder
Plan a cylinder replacement around hot-water demand, pipework, pressure, controls, removal and the service space the new unit still needs.
Read guide →16Choosing and sizingSize a heat battery
Turn showers, baths, heat loss and charge windows into a useful sizing brief without relying on a one-size-fits-all household table.
Read guide →17Installation and supportHeat battery policy tracker
A dated record of the official UK pages that affect heat battery support, product standards and installation tax treatment.
Read guide →Work out the money
7 guidesHeat batteries on Economy 7
Check cheap hours, meter setup, charge time and day rates before pairing a heat battery with Economy 7.
Read guide →02Costs and tariffsCost and payback
Compare equipment, installation, running costs and avoided costs without turning an optimistic tariff gap into a savings promise.
Read guide →03Costs and tariffsWork out running costs
Calculate the value of shifting heat to an off-peak period, then account for losses, installation cost and the system you are replacing.
Read guide →04Costs and tariffsCompare with gas costs
Electricity and gas unit rates cannot be compared directly. Account for system efficiency, standing charges, tariff periods and the demand being replaced.
Read guide →05Costs and tariffsSmart tariffs and heat storage
Fixed, dynamic and split cheap periods can reward controllable heat storage, provided charging power, controls and household demand fit the tariff.
Read guide →06Costs and tariffsExport or store solar heat
Work out the opportunity cost of diverting surplus solar into a heat battery instead of exporting it or storing electricity.
Read guide →07Interactive toolTariff calculator
Enter your own daily heat demand and electricity rates to estimate the annual value of moving energy into a cheaper tariff period.
Use calculator →Compare your options
11 guidesHeat battery or combi boiler?
Compare a stored-heat system with a gas combi on hot-water flow, space, heating design, tariffs, electrical work and the gas connection.
Read guide →02Compare your optionsHeat battery or electric boiler?
Direct electric boilers make heat when called; a heat battery can charge earlier and release later. Compare tariff exposure, capacity and electrical load.
Read guide →03Compare your optionsHeat battery or heat pump?
A heat pump makes heat efficiently; a heat battery stores heat for later. Learn when they compete, when they work together and what to ask first.
Read guide →04Compare your optionsHeat or electrical battery?
A home battery can power many circuits; a heat battery stores energy for hot water or heating. Compare the later use of each kWh.
Read guide →05Compare your optionsHeat battery or cylinder?
Compare heat batteries and hot-water cylinders on space, energy source, flow rate, losses, installation and everyday use.
Read guide →06Compare your optionsHeat battery or solar thermal?
Solar thermal collects heat; a heat battery stores it. They can work together, but neither replaces the other's core job.
Read guide →07Compare your optionsHeat battery or storage heater?
Both can charge off-peak, but storage heaters release heat into rooms while a heat battery may serve hot water or a wet heating system.
Read guide →08Compare your optionsHeat battery or thermal store?
The terms overlap. Compare storage medium, water arrangement, heat sources, useful output and the job each proposed vessel performs.
Read guide →09Compare your optionsDiverter or heat battery?
If you already own a hot-water cylinder, compare a solar diverter with replacing the store before buying a more complex system.
Read guide →10Makers and productsCompare UK makers
A criteria-led way to compare domestic thermal storage without ranking products whose current specifications have not been verified.
Read guide →11Makers and productsSunamp explained
A neutral overview of Sunamp's phase-change heat batteries, the jobs they are designed for and the evidence to request before choosing a model.
Read guide →Live with it
5 guidesLifespan and maintenance
Check what needs servicing, which parts can fail, how warranty cover works and what happens at the end of the product's life.
Read guide →02Ownership and maintenancePower cuts and backup
Stored heat does not guarantee hot water or heating during an outage. Pumps, valves, controls and water pressure may still need electricity.
Read guide →03Ownership and maintenanceTroubleshooting guide
Use symptoms, control history and installation records to give support useful evidence without opening covers or bypassing safety devices.
Read guide →04Ownership and maintenanceWarranty and support
Separate product, installation and component cover, then check labour, travel, servicing, transfer and the route if a firm stops trading.
Read guide →05Ownership and maintenanceSelling a home with heat storage
Gather certificates, warranties, controls, tariff assumptions and service history so the next household can operate the system safely.
Read guide →