Demand response

Electric boiler demand response

A controller that sheds heating stages, a thermal store that says how much can be shed, and a record of what the site took back afterwards.

Build this system See the hardware
ZDR-21 Demand Response Controller
ZDR-21Demand response control
TES-22 Probe Temperature Sensor
TES-22Pipe probes
ZGW-20 Gateway
ZGW-20Gateway with Edge
Measure
Boiler stage power, store and circuit temperatures, contactor feedback, and the recovery afterwards
Rule
Event and rebound energy are measured against the programme's baseline DOE
Sensors
ZDR-21, Class 0.5S metering, its own relay, 20 ms event recording and GPS time sync ZDR-2X datasheet (PDF, opens in a new tab)
On site
ZGW-20 Gateway, eligibility rules, the event record and the thermal flexibility picture ZGW-20 datasheet (PDF, opens in a new tab)

Hardware for electric boiler load shedding

One controller per dispatchable stage, temperatures that bound what may be shed, and the Gateway that decides whether the site is eligible right now.

If pressure or level bounds the service

TES-22 and ZIO-20 share one enclosure with different terminals inside, so the ordering code is what you specify.

What decides whether a stage may be shed

The thermal service comes first. Every measurement here exists to say whether the site can give up heat right now, and for how long.

What decides whether a stage may be shedThe controller sits on the boiler's supply. The store temperatures say how long the building can coast without it. Heat source boiler or heat pump Heating load radiators or coils Thermal store Flow Return Pump HM Heat meter Board Fuel meter ZGW-20 GatewayEdge on site ZDR-21 TES-22 · flow TES-22 · return ZIO-20 What decides whether a stage may be shedThe controller sits on the boiler's supply. The store temperatures say how long the building can coast without it. Heat source boiler or heat pump Board Fuel meter Store Flow Return HM Heating load ZGW-20 GatewayEdge on site ZDR-21 TES-22 · flow TES-22 · return ZIO-20
The controller sits on the boiler's supply. The store temperatures say how long the building can coast without it.
Sensor positions for what decides whether a stage may be shed
PositionWhat it tells youReferenceSensor
Stage power How much each stage is actually drawing, which is the reduction on offer Class 0.5S metering in the controller itself ZDR-2X datasheet (PDF, opens in a new tab) ZDR-21 (on this page)
Store and circuit temperature How much stored heat there is, and how fast it is being used A matched pair on the same circuit, ±0.2 °C in the normal range TES-2X datasheet (PDF, opens in a new tab) TES-22 (on this page)
Pressure or level The other limits the thermal service has, where they exist The transmitter's own range and scaling ZIO-2X datasheet (PDF, opens in a new tab) ZIO-20 (on this page)
Contactor feedback Whether the stage actually opened, as opposed to being told to Measured power is the feedback: a command without a change in power is a failed shed ZDR-2X datasheet (PDF, opens in a new tab) ZDR-21 (on this page), measured power

  • Monitoring thresholds are not protection. The boiler's own pressure, temperature and heater interlocks stay in charge. An eligibility rule can only decide whether to ask.

  • Recovery is part of the event. A shed that is paid back at full power ten minutes later can cost more than it earned. Measure the whole window.

Eligibility, dispatch and recovery in Edge

The rules run on the Gateway, next to the measurements they depend on.

Eligibility before the event
A calculated sensor combines store temperature, service demand and stage state into the capacity that can honestly be offered.
A shed is proven, not assumed
The measured power before and after each stage change is kept, so a command that did nothing is visible.
Stale data gives up control
If a temperature or a stage measurement goes stale, the site withdraws rather than shedding blind.
The recovery is measured too
The window after the event is recorded at the same interval, so rebound can be compared with the reduction.

Commissioning checks

Take these in order, with the person responsible for the heating service.

  1. Write down what may not be given up

    Record the temperature, pressure and service limits, the minimum on and off times, and every interlock.

    Pass when the list is agreed and signed by whoever owns the heating service.

  2. Operate each stage locally

    With the site's agreement, open and close each dispatchable stage from the controller.

    Pass when the measured power changes by the expected amount within the expected time.

  3. Prove the failure behaviour

    Simulate stale thermal data, a lost connection and a failed acknowledgement in turn.

    Pass when each one produces the declared safe state, which is usually no shed.

  4. Run a bounded event

    Shed for the programme's duration while trending electrical, thermal and service variables together.

    Pass when the service stayed inside its limits and the reduction is visible at the connection.

  5. Measure the whole recovery

    Keep recording until the plant is back to its normal pattern.

    Pass when the rebound is quantified and inside whatever the programme allows.

What monitoring does not replace

A demand-response system asks. The plant's own controls decide.

  • It must not replace boiler safety, pressure protection, burner or heater interlocks.
  • A nameplate kilowatt figure is not guaranteed dispatchable capacity at every load and temperature.
  • Commercial availability and settlement follow the programme's baseline, telemetry and event rules.
  • Electrical work on the stages stays with the qualified person who did it.

Sources and related guides

Sources

Related

Reviewed by EpiSensor Engineering on . Revision 4.

See how much heating load can honestly be offered

We will work out what can honestly be offered, and how the site proves it afterwards.

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