No hot water and no power light?

1. Check the fuse has not tripped. Please note minimum 40 (a) fuse required
2. If the fuse is ok check the flow rate. The unit requires a minimum flow rate of 3 litres per minute to switch on (you can measure this by turning on the hot outlet and using a litre jug and see how many times you fill the jug in one minute.
3. If the flow rate is below 3 litres per minute then you will need to adjust the flow rate using the flow adjustment screw to allow more water to enter the unit (this is the brass screw located on the cold water inlet inside the unit (see manual for further details) - though please be aware, that if you open this valve too much, then the water flow could be so high that it passes the element too quickly to heat up.
4. If flow rate and electrical connections are ok a service engineer may be required

If you have no hot water or luke warm water and power light is on, the chances are in this instance the flow rate of the water is too fast and passing the element too quickly to heat up. Adjust the flow rate adjustment screw to lower the flow rate.