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 -Heat Pump (with immersion heater output) |
| 9 - Heat pump immersion heater relay | 10 - Heat pump hot water timer |
Functional Description
In this application the water is heated by eddi with the immersion heater when there is a relativity small amount of surplus power (e.g. < 1kW). But when there is enough surplus the heat pump is used to heat the water instead. This configuration takes advantage of the higher efficiency of the heat pump compared with the immersion heater, whilst ensuring no surplus power is wasted.
For this application the water heating element (4) is wired to the eddi Heater 1 output. The water heating timer control (10) for the heat pump (8) is connected to the Relay 1 normally open contacts of the Relay & Sensor Board (6).
Most heat pumps require control of the immersion heater in the hot water cylinder, this is to periodically heat the water to a higher temperature in order to kill any Legionella bacteria that may have built up in the stored water. Remember it is not permissible to 'back-feed' the eddi device; a voltage supply must not be connected to the heater outputs. Because of this, the heat pump immersion heater relay (9) needs to be connected to the eSense input of the Relay & Sensor Board (6) instead of the immersion heater element (4). In this application, the eddi is configured to respond to the eSense signal by fully switching on Heater 1 output regardless of available surplus.
Installation of the temperature probe (7) is optional; the heaters' mechanical thermostat can be used instead if temperature reading is not required.