Economy7 Storage Heater not heating enough hot water

Hello guys,
We just moved into a new flat that has an electric storage heater. We have been suffering from not having enough hot water since we moved in here. For example, this morning I took a 10mins shower in the morning(7:30) (our shower head is kinda broken so it sprays less amount of water) and then my missus tried to take a shower around 16:00. We left the Boost option on at least 1 hr before. However, she didn't have almost any hot water. 

We shared this with our landlord and she sent a guy in. He checked the storage heater and told us that it all seems ok. He said that it has a capacity of 150l so if we take 15 mins of the shower it is normal that we will be out of hot water. This sounds pretty ridiculous as just like any normal person, we want to have hot water during the whole day. 

Could you please advice on what might be wrong here? I read historical posts but they mostly end at some point without agreeing on a solution. 

Thanks in advance!


  • JGB1955
    JGB1955 Posts: 3,522 Forumite
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    edited 9 December 2022 at 6:04PM
    Taking a 15 minute shower is almost guaranteed to empty the immersion tank (which is what, I'm assuming, you are referring to as the 'water heater'.  Try a 5 minute shower.  Your electric storage heater is likely heating the 'load of bricks' in the corner of your living room....nothing else.
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  • stewie_griffin
    Could you ask your landlord to fit an electric shower? It won’t be cheap to run but you’ll always have hot water
  • Jyana
    Jyana Posts: 748 Forumite
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    edited 9 December 2022 at 6:38PM
    How long are you heating the water for over night, and to what temp? And by boost, do you mean the immersion/the switch near the water tank or a switch that is near the radiator?
  • chris1973
    chris1973 Posts: 965 Forumite
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    edited 9 December 2022 at 6:51PM
    Sounds like you have the older type of two element immersion heater, with an Element in the bottom of the tank, which activates during the cheaper E7 Off Peak hours and heats the entire tank of water, and a second Element about 1/4 of the way down from the top of the tank which operates during the peak rate daytime hours using the "boost" button.  The Boost Element is only designed to heat the top 1/4 of the tank to give enough hot water for washing the dishes, filling a sink etc later in the day, and is unlikely to heat enough in the top section of the tank to run a full shower.

    Back in the 1970's when this combination was popular, the immersion controller would be marked "Bath" for the bottom element which heated the entire tank contents, and the top element heating the top quarter of the tank was marked "sink" pretty much indicating the water capacity which each element heated!. These days that kind of labelling has changed, and now the top element is marked simply as "boost" but the principle, operation and amounts of water heated by each element is exactly the same.

    If this is the type of tank you have (You should see two elements in the  tank each with its own flex) then you'll either need to get an Electric Shower, or both have a quick shower first thing in the morning, sharing the tank of hot water which the E7 period has heated for you overnight.
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  • EssexHebridean
    EssexHebridean Posts: 21,482 Forumite
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    If you shower before the rate changes over (roughly 0700 here at the moment) then you may find you get slightly more time from it as it should be heating the water that refills into the tank. But yes - as others have said, 15 minute showers are pretty long - I suspect if you did have an electric shower you’d be finding that a pretty expensive habit! 
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  • macman
    macman Posts: 53,098 Forumite
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      A storage heater is a space heater-it doesn't heat any hot water. Are you referring to an immersion heater?
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  • Mstty
    Mstty Posts: 4,209 Forumite
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    Weekend shower 4 minutes, weekday shower 2 minutes max

    Don't shave in the shower anymore like I used to 
  • RedFraggle
    RedFraggle Posts: 1,309 Forumite
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    Is it a thermal store? Something like a Gledhill?
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  • matelodave
    matelodave Posts: 8,622 Forumite
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    edited 10 December 2022 at 5:15PM
    Dunno what sort of shower head you've got but it's not hard to use 10 litres a minute which equals 100 litres in ten minutes which probably uses most of the tank in one go.

    It takes a 3kwh immersion heater around 3 hours to heat 150 litres of water from 10 degrees to 60 degrees so you need to ensure that the heater is left on overnight on the off-peak rate (the thermostat will control the temperature so it will only take as much heat as it needs)

    Do the sums - 3kw x 3 hours - 9kwh at the off peak rate, say 25p/kw = £2.25, at the capped electricty rate of 35p = £3.15 and at what ever your silly peak rate is, say 45p = £4.05, so your ten minute shower is using around 6kwh and  could be costing you the best part of £2 or more

    Get a lower flow shower head (ours does 6 lpm) and then limit your shower time to 5 minutes which will reduce your consumption to just 30 litres.

    I'm like Mstty, two minutes for a shower = 12 litres. My wife can manage it all in 4-5 minutes. We only heat the water to 45 degrees and we've plenty of hot water for two showers, any other use during the day and even another two showers the next morning.

    Chewing your way through vast quantities of hot water is costing you dearly in energy, especially of you also waste it by rinsing stuff under a running hot tap. An electric shower which uses peak rate electricity (or using the boost switch to give you even more will double your energy costs) As said above if you can have your shower before the off-peak rate changes  will ensure that the tank at least gets some reheating at the off-peak rate.

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  • k_man
    k_man Posts: 1,636 Forumite
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    10 litres a minute which equals 100 litres in fifteen minutes

    really? 😉
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