Clueless about our immersion heater in new electric only flat :(

[Olive45]

Just moved into a 2 bed flat which is electric only, it wouldn't have been my first choice but the rental market is crazy at the minute and it is take what you can get round here! We (boyfriend+I) have never lived anywhere that was just electric before, nor have we ever used an immersion heater before - so we have no idea what we are really looking at. But we are now stressed that we will now be paying exceptionally more than we realised...

We have asked the landlord for any info, and he has said that he doesn't know about it nor has any manuals/paperwork and no previous tenants have ever asked about how it works. It is an OSO hotwater immersion heater, and lots of googling usually suggests there would be a thermostat or a timer on the wall to control it (although we are not on any sort of economy meter, so no discounted electric at night so I assume that wouldn't be helpful anyway)- but we can't find anything. We never seem to run out of hot water when showering etc, but if we turn only the hot water tap on (without the cold tap) it is absolutely scalding. We want to turn it down as it is inconvenient but also we are concerned maybe this being so hot is costing a lot of money? There are 2 switches on the wall that are both on, and that's all we know!

To sum up, we are scared that this immersion heater is going to be super expensive but we have no idea how to even begin managing it. Does anyone have any tips on how to save on bills in an electric only flat? Our average usage so far is 14 kWh/day - is this normal for just 2 people (no heating on, dishwasher on eco-mode every night, 2 laundry washes a week, cooking most evenings)

Sorry for the information overload, it actually just feels nice to type this all out as a bit of a stress release!!

Hey,

If you have any luck finding model number on it anywhere then you can find the instruction manual on the suppliers website here, or just try find the one that looks like yours:
osohotwater.co.uk/downloads/

As for changing the temperate, some of the instruction manuals suggest that there may be a little black gadget right at the top of the tank where the two pipes are running down into it. If there's one on yours, then it seems that that's where you turn down the temp.

Other than your hot water temp being too high, the brand seems like a good quality and energy-efficient water heater anyways.

Ok, first off, I am not an electrical engineer, plumber, or professional in any capacity qualified to install these things, so I'm giving you advice purely as a layperson with some experience of living in properties with immersion heaters.

The tank you have has it's own built in thermostat on the top, behind the grey collar. If you think your hot water is too hot, you should be able to locate this and turn it down. I suspect what is happening is your tank is heating the water to the set temperature, switching off, then reactivating and re-heating the water every single time it cools. 14kw/h per day does seem a rather large consumption for two people living in the circumstances you describe, and I'd bet it's the 'always on' immersion heater that is behind this.

I'm not familiar with how power to these specific units is normally supplied, and I do not know whether it's safe and advisable to operate them on an 'as and when' basis, but ordinarily most immersion heaters can be switched on simply to heat water as and when it is required, but remain in a constant 'off' state otherwise in order to save on cost.

I'd suggest you switch both of the wall switches off, leave it for an hour or so in order to ensure the water in the tank has cooled, then turn them on one by one until you hear the elements working to heat the water. There should be no theoretical issue with you doing this on an 'as and when' basis, but you really ought to consult with the manufacturer or a qualified professional to make sure of this.

I know my brother only switches his immersion heater on for an hour or so before he needs it and then switches it off again so it's not on all time.

What sort of heaters do you have? If they are storage heaters you might be better having an economy 7 meter/tariff where you get cheaper electricity overnight when the heaters are charging.

Googling suggests there is a top and bottom heating element and that's why there are 2 plugs. I doubt you'd need both on at once unless you use a lot of hot water. Maybe play about with timings. Can you see where each cable goes to at the cylinder?

If you are using 14kwh a day that’s quite a lot. I only use about4; 8 when I have the dishwasher and washing machine on.
The fact that the hot water is scalding suggests that the tank is being heated to the maximum all the time.
Turn off both switches and see how quickly you run out of hot water. I bet your usage will drop dramatically.
I hear my hot water by gas and generally only put it on for maybe an hour if that.

Actually 14kwh isn't loads if you only have electric and that includes your hot water cylinder and your heating. An average hot water cylinder uses 3kwh per hour so if the water is on for a couple of hours each day, and then you use the heating for an hour or two as well, hey presto you'll hit 14kwh.

Dishwashers and washing machines use a lot of energy. As does the oven. Even the hob!

I average 10-12 kwh per day and that's using a hot water cylinder on a timer, with little/no heating (brr), washing up by hand and trying to minimise oven/hob/washing machine use.