In this article:
- Overview
- Wiring Diagram
- Functional Description
- Settings Required
Overview
The following wiring diagram shows a suggested application and are examples only; there are many more possibilities.
Please take a look at the Safety section within the installation manual and read all the installation sections before attempting to install the eddi.
A good level of electrical competence and a reasonable understanding of domestic plumbing systems is assumed for studying this application example.
Wiring Diagram
| Key for Wiring Diagram | |
| 1 - eddi device | 2 - Mains supply (230V AC from B16 circuit breaker or 13A fused spur) |
| 3 - Hot Water cylinder | 4 - Heating element 1 (max. 3.7kW) |
| 5 - Isolator (20A double pole) | 6 - Relay & Sensor Board (optional add-on for eddi) |
| 7 - Temperature probe (type PT1000) (optional) | 8 - Mains supply (off-peak timed) (230V AC from B16 circuit breaker or 13A fused spur) |
Functional Description
Some electric-only households that employ dual tariff billing use two separate electricity meters; one is live for 24 hours and the other is off-peak timed and bills at the economy rate. Only some appliances are connected to the off-peak supply (usually water heaters and storage heaters).
This application enables automatic boosting of water heating when the economy tariff is available whilst also using any surplus generated power to heat the water. Both the top and bottom immersion heaters can use surplus power and be boosted with peak-rate electricity. However, only Heater 2 can be boosted with off-peak electricity (See page 42 if it is desired to have Heater 1 boost using off-peak power).
eddi is powered from the 24-hour supply and the bottom immersion heater is wired directly to Heater 1 output. During the economy tariff times, power needs to be drawn from the off-peak tariff meter, to achieve this the top immersion heater is switched from the eddi Heater 2 output and the off-peak supply using both relays of the Relay & Sensor Board (6).
Heater 1 (the top immersion heater) is heated with surplus power until the water at the top of the cylinder is hot and the thermostat opens, then eddi will immediately switch over to Heater 2; heating the bottom of the cylinder. This makes the most of surplus energy as sometimes there will not be enough to heat the whole volume of the cylinder; it's best to heat a smaller proportion (i.e. the top) first so there is some usable hot water, rather than a larger volume of warm water.
During heating of Heater 2, eddi will switch back to Heater 1 every 15 minutes to check if it can store any more heat.
When the water is fully heated, any surplus power will be exported, eddi will switch back to the priority heater and check the lower priority heater every 15 minutes.
If eSense Input is set to Boost Enable 2, the BOOST TIMER screen for Heater 2 will include an option to enable the boost timer only when the eSense input is live. In the BOOST TIMER, the e can be toggled on/off, if e is present, the boost will activate only when the boost times are valid and the economy rate tariff is available.
Alternatively the eSense input can be used to activate the boost whenever the economy tariff rate electricity is available, regardless of boost times. To do this, eSense Input should be set to Boost 2. When using this option, the Boost Timer is not needed.
Installation of the temperature probes (7) is optional; the heaters' mechanical thermostat is used by eddi if temperature readings are not required.
The eddi device should be labelled with a “dual supply” warning.
Settings Required