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.
Turn off and on to suit your needs. Timers available so can be switched off and on to suit your needs. Not efficient to constantly heat water thats not needed, you wouldn't do it with a kettle just in case you wanted a cup of tea
In the main only worth switching on/off if the electric has different rates at different times of the day. The amount of water often 40 gallons takes a lot of heating and cooling, so switching off for 8 hours while at work it would only cool a few degrees anyway. My water is heated by oil, and there is no thermostat on the tank, so the boiler will unless switched off heat the water in the pipes many times a day, so not the tank which wastes money but the pipes, so switches on for half hour three times a week in summer, to save heating pipes. There is a system called the Willis where the water is heated in a separate tank and heats the 40 gallons from the top down, so the time running does affect how much hot water you have, but it seems only the Irish have the knowledge to use the system, so unless you live in Ulster your not likely to have that system. So no point turning it off.
Only switch on when required, I would fit one of these https://www.ebay.co.uk/itm/19314068...i2nHhmW2wpgBKcaJJ5lgvh5IQm|tkp:Bk9SR8SHi_XdYA stops you inadvertently leaving it switched on.
This unit the Willis Water heater allows you as said to heat from the top of the tank down, It is very clever as you can get enough hot water to fill a sink in a few minutes, and having a timer with one of these makes a lot of sense, however most of us have the immersion heater built into the main tank, this calculator allows you to see the problem 4 hours and 35 minutes to heat up, even longer to cool down, with that time scale not worth the effort to turn on/off with timer, as it simply will never cool down anyway. The timers designed for immersion heaters are for when you have off peak power, so you pay less if heated at set times, or when using the Willis system, other wise you will get a saving but it is so small not worth the effort, as said I only heat water every other day, and it never gets cold, 40 gallons takes a lot of cooling, it only saves on oil due to not heating the pipes.
I have missed out one point, legionnaires dies at between 60 - 70 degs C. The aim is to fully heat the stored water at least once a week, until turned it off my Nest Gen 3 did it once a day, which since there is no thermostat on my water store is a little pointless, as Nest has no way to know when hot enough.