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 - Economy rate electric sense wiring (live only when economy rate is available) |
Functional Description
It is common for electric-only households to employ dual tariff billing. This application enables automatic heating of water when the economy tariff is available whilst also using any surplus generated power to heat the water.
The economy rate electricity can be time-based or random, in either case, eddi can be set to heat the water at the economy rate whenever possible, or at the economy rate only during certain times.
Heater 1 (the top immersion heater) (4) 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 (6); 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 1&2, the BOOST TIMER screen for either heater 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 1&2. When using this option, the Boost Timer is not needed.
If automatic sensing of economy rate times is not needed, the boost timer can be simply set to coincide with the economy tariff times. In this case the Relay & Sensor Board (6) and the eSense wiring (8) are not required.
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.