Is my immersion heater working?!

So how can you tell if your immersion heater is working? I get asked this quite a lot. 

Well firstly, if your immersion heater is working and turned ON, you should get plenty of hot water at the hot taps after waiting for a couple of hours. But assuming you’re in a hurry and want to know NOW rather in a couple of hours, the easiest way to tell is to look at your electricity meter. 

Assuming you have an ordinary digital electricity meter like mine in the photo, it will have a flashing red LED. The faster it flashes, the more electricity you are drawing. So start by turning your immersion heater OFF, then find your electricity meter.  Checking the LED flash rate. Hopefully it is flashing really slowly, like one flash every few seconds or even once a minute. If this is the case, this is good because it means you have very little background electricity consumption from ‘vampire’ appliances, those plugged in but not turned on such as the telly, phone and laptop chargers etc etc.

Now turn the immersion heater ON and return to the meter. You should see the red LED flash rate speed right up to one flash per second. This tells you your immersion heater element is working and drawing power, and heating up your water. If the flash rate does not change, then the immersion heater is not working and no matter how long you wait, there will be no hot water. I suggest you replace the fuse and if still no change, call an electrician or boiler technician. 

The exact speed of flash tells you how much power is being drawn. Every flash indicates 1 Watt-hour of energy consumed, so the faster the flash the faster you are using energy. After 1,000 flashes you’ll have used one unit (kWh) of electricity which at prices today, 3/9/22, will probably have cost you about 30p.