Hi all, I have recently moved into a flat that runs on electric only and I have an immersion heater. The heater turns on and off during the day, I presume it has a temperature sensor of some sort. The heater is using up quite a lot of electricity during the day. Im only at home in the evening. The water within the tank is literally only used for the bathroom tap and the kitchen tap. It’s only me that lives in the flat. Would it be okay to have it switched off during the day and only turned on when needed? Or can a timer be fitted? Not too sure what’s most efficient and if it’s good/safe to turn it on and off constantly. Thank you.
To give a full answer we would need more information, in particular whether the hot water cylinder has one or two immersion heaters, and whether you are on an Economy 7 type electricity tariff. As an interim answer: 1. If you have only 1 immersion heater, a timer could save you money, which given the current rising costs, could be quite a bit. 2. If you have 2 immersions: 2a. The lower one will be on the economy tariff if you have one, which means electricity only goes to it during fixed hours, and generally might as well be left permanently on. 2b. The upper one will be for "top ups", and you may well want to leave it permanently off. 2c. The lower one will heat the whole cylinder, the upper only about the top third of the cylinder.
Do not forget whichevr way you choose to operate it, efficient thermal insulation to the cylinder and nearby hot pipework is essential
The coming energy crisis means all the economical savings (being based on "save a bit" from a "you have to be able to spend it first) are now out of the window (as very few will be able to afford to spend it in the first place). The days of having readily available stored water at constant temperature via a thermostat could will be over. It could well work out cheaper to just switch the IH on and off manually.
There will probably be a temperature setting inside the cover over the immersion element. You could consider reducing the temperature. Note there are live terminals inside the cover so you should turn the heater power off to be safe when opening it.
I would expect that the cost of maintaining each additional degree of temperature would increase progressively or even exponentially.
We run ours at night. It does come on again after the kids bedtime just in case the Mrs wants a bath. But to be honest... our electricity bills are sky-high and always have been... so I'm not sure I can really recommend the right approach. My theory with my setup is that it's on a thermostat so should only turn on when the water gets below a certain temperature. So theoretically it could be left on all the time... however... my fear is if it's pointlessly turning on and off all day it could be heating the water in short bursts throughout the day and just wasting a load of electricity in the process. I find having it set to about 60-70 degrees, turning it off at 6am when the cheap electricity ends, it is still warm enough for the kids bath at around 6pm in the evening. I think a combination boiler would be a much better solution though. That way it only runs on demand. We're on oil heating so I have to keep an eye on the tank level and can't just run the oil boiler all the time without the possibility of the tank running out unexpectedly at a time when it isn't convenient to spend £1000 topping it up.
When we had a hot water cylinder we boosted it twice a day - an hour at about 6 in the morning, and again at about 4. That worked well for family of 4.
If you don’t need the convenience of hot water on tap, just boil a bit in a kettle when you need it. It will work out cheaper. You could install some sort of point-of-use water heating / tap but there is a high up-front cost. If you have enough dishes and cutlery then running a dishwasher every week or two is a cost effective way of heating water.
Pointless keeping water hot if it is not going to be used IMO. Just one person in the house / flat, then just heat it as and when required. Maybe consider a water heater in the kitchen, fitted with a timer (maybe a Timeguard NTT03) and set it to suit your needs.