Quick answer: When specifying heating equipment for a project, four questions separate a workable specification from a wish list: what is the peak heat load, how much storage is required and over what bridging period, which energy sources must the controller accept, and what certifications and test evidence will the project's regulator or insurer require. Answering those four before discussing features keeps a specification anchored to requirements the installation will actually be judged against.
Start from the load, not the equipment
Heating projects that go wrong usually do so at the specification stage rather than the installation stage. The most common root cause is selecting equipment from a catalogue by floor area, then discovering during commissioning that the building's actual heat load is outside the assumption the catalogue figure was based on.
The fix is procedural: establish the peak heat load first, in kilowatts, from building construction, glazing, local design minimum temperature and target indoor temperature. Every subsequent decision — capacity, storage volume, power level, control complexity — references that figure. Without it, the remaining decisions have no anchor and tend to be resolved by cost alone, which is how undersized systems get installed.
For single residential units, an informed estimate is usually adequate. For commercial, agricultural or multi-unit projects, a formal calculation is worth commissioning because the cost of getting it wrong scales with the number of occupants and the consequences of failure.
Define the bridging period before sizing storage
Storage capacity is meaningless without a stated purpose. The useful specification is a bridging period and a load: how many hours must the building be heated without drawing from the grid, and at what heat output during that period.
That framing produces a defensible number. If a building needs 6 kW of continuous heat for four hours of peak-tariff morning demand, the storage must supply roughly 24 kWh over that window, plus allowance for standing losses from the store itself. Presented that way, a supplier can either meet the requirement or explain why a different configuration would serve the project better.
| Project type | Typical bridging need | Why |
|---|---|---|
| Residential, occupied all day | Bridge the peak-tariff windows only | Demand is continuous, so storage shifts timing rather than covering gaps |
| Residential, unoccupied daytime | Cover the setback recovery period | Comfort is only required during defined occupied hours |
| Agricultural / livestock | Full overnight coverage without fail | Frost protection is a welfare and asset-protection requirement, not a comfort preference |
| Commercial, daytime occupancy | Bridge morning peak, then run on tariff | Demand aligns closely with expensive tariff hours |
Specify the control interface by the energy sources involved
Controller requirements follow directly from which energy sources the project will use. A single-source grid installation needs tariff-aware scheduling and reliable setback programming. A hybrid installation needs prioritisation logic, because the value of the system depends on using renewable output when it is available and switching to grid at the cheapest suitable time.
Two specification points are frequently omitted and later regretted. The first is logging: without a record of when the system ran and how much power it drew, there is no way to verify that an off-peak or renewable-priority strategy is working. The second is power level flexibility: a system that can step between power tiers can operate within a constrained supply and can absorb variable renewable output, while a fixed-power unit cannot.
Both points are inexpensive to specify up front and difficult to retrofit, which is why they belong in the initial requirement rather than the final negotiation.
Establish the certification and evidence requirement early
Certification requirements are project-specific and slow to obtain if they were not anticipated. For projects intended for the domestic Chinese market, CCC certification is the baseline. For export to European markets, CE marking is required, and the supporting technical file must exist — not merely be referenced.
The practical step is to define the evidence pack before ordering: which certificates must be presented, in whose name, and what test documentation accompanies them. Certificates issued to a different legal entity than the purchaser, or covering a model variant that differs from the unit supplied, create customs and compliance problems that surface at the worst possible moment.
Additional project-specific requirements may include electrical safety testing, pressure testing of hydraulic components, and material declarations where the installation is in a public or healthcare building. Asking for the evidence pack early also reveals whether a supplier actually holds the certifications claimed, which is useful information regardless of the project.
A six-item specification brief
- Peak heat load in kW, with the assumptions behind it: construction, glazing, design minimum temperature, target indoor temperature.
- Available electrical supply: single or three phase, main protection rating, existing large loads.
- Storage requirement expressed as kWh over a stated bridging period, plus the acceptable physical footprint.
- Energy sources the controller must accept and prioritise, including any renewable input.
- Control and logging requirements: scheduling granularity, data retention, export capability, remote access.
- Certification and documentation: which marks are required, in whose name, and what test evidence must accompany delivery.
A brief covering these six items lets a manufacturer give a specific proposal rather than a general quotation, and it makes competing proposals comparable on the same terms. It also surfaces the genuine constraints early, while they can still be designed around rather than discovered at commissioning.
Frequently asked questions
What information should a heating project enquiry contain?
At minimum: heating area and building type; construction and insulation condition; total glazing area and type; local design minimum outdoor temperature; target indoor temperature; available electrical supply (phase and main protection rating); and whether any renewable energy sources will be connected. With those items, a supplier can size a system without further clarification in most cases.
How is the bridging period determined for a storage specification?
From the tariff structure and the building's occupancy pattern. Identify the hours when electricity is most expensive and the hours when it is cheapest, then calculate how much heat the building needs during the expensive window at the prevailing outdoor temperature. That heat demand, divided by the hours it must be covered, gives the storage requirement. Add allowance for standing losses from the store.
Do customized units delay a project significantly?
Heating capacity, voltage, control functions, housing finish and piping direction can all be specified, and customization affects the same production and testing sequence as a standard unit. The variable is whether the change touches tooling or certification. Changes within the existing platform — power tier, voltage, controller configuration, piping orientation — are generally straightforward. Changes that require new certification for a model variant take longer and should be raised at the earliest stage of the project.
What certification do I need for export to Europe?
CE marking, with the supporting technical documentation, is the baseline for heating equipment placed on the European market. Confirm at the quotation stage that certificates will be issued in the name of the purchasing entity if that is required, and that the documentation covers the exact model and variant being supplied. Documentation covering a different variant is a common and avoidable source of delay at customs.
Is three-phase supply always better for a heating project?
Not always better, but it removes a constraint. Three-phase supply allows higher total heating power without overloading any single phase, which suits larger residential, commercial and agricultural installations. Where three-phase is unavailable or expensive to install, a system that can operate at a reduced power tier within a single-phase supply is often the practical alternative — accepting slower recovery in exchange for avoiding a service upgrade.
Preparing a heating specification? Send us your heat load and assumptions, electrical supply details, storage and bridging requirements, planned energy sources and certification needs. Our engineering team will respond with a specific configuration proposal rather than a general product quotation.