Immersion hot water not lasting long enough!

[Rodders53]

Do you own or part-own, as in shared ownership, this flat?

If owned why do you need Housing Association input/approval?
If part owned then it makes better sense.

I'd suggest that a larger capacity unvented HW storage tank (170 l or even 210 l) is another option to give a proper shower at mains water pressure and would also fill a bath when needed. Then you'd lose that cold water storage tank -- which is barely at head height and exactly why a shower doesn't work! Probably more expensive than the other options though.

Dimplex Quantum are high heat retention storage heaters https://www.tlc-direct.co.uk/Products/DXQM100.html and have a good reputation if installed and used correctly. Likely replacement would be a more modern Dimplex equivalent - but probably insignificantly superior (other than shiny and new)? Snake oil peak rate electric radiators must be avoided.

Do you have a smart meter and In Home Display to monitor the load being consumed... it would allow you to check the load the current immersion(s) present if you switch then on/off. Along with the thermostat settings it may help explain why things are so poor at present.

 

[StephenStephen]

Just for clarity, any immersion heater is pretty much 100% efficient - it converts electricity into heat.

 

[LeeFL]

Do you own or part-own, as in shared ownership, this flat?

If owned why do you need Housing Association input/approval?
If part owned then it makes better sense.

No I don’t own or part own the flat, I’m renting via Clarion Housing Association.

I'd suggest that a larger capacity unvented HW storage tank (170 l or even 210 l) is another option to give a proper shower at mains water pressure and would also fill a bath when needed. Then you'd lose that cold water storage tank -- which is barely at head height and exactly why a shower doesn't work! Probably more expensive than the other options though.

Yeah I can see what you mean, but I doubt my HA would even agree to large tank.

Dimplex Quantum are high heat retention storage heaters https://www.tlc-direct.co.uk/Products/DXQM100.html and have a good reputation if installed and used correctly. Likely replacement would be a more modern Dimplex equivalent - but probably insignificantly superior (other than shiny and new)? Snake oil peak rate electric radiators must be avoided.

Yes I’m beginning to hear more and more bad things regarding the electric radiators. I have admit that Dimplex seem to be efficient but as I’m so new to this kind of thing, I’ve lived here since May and only begun to turn them on in the last few days, much to my anxiety given the concerns I’ve read elsewhere online about storage heaters and the high bills, but so far I’m being charged £2.75 to £3.81 per day since Thursday (when I first turned them on), today has reached £4.29. Given the continued rise in Gas, I’m being told by those around me I’m worrying too much about it and it’s likely going to be not ‘far off’ from what central heating costs would be, proof will be in the pudding of my Oct-Nov bill, I’m on a fixed E7 tariff with Octopus.

Do you have a smart meter and In Home Display to monitor the load being consumed... it would allow you to check the load the current immersion(s) present if you switch then on/off. Along with the thermostat settings it may help explain why things are so poor at present.

Yes I do, but the IHD often loses signal, no matter where I put it in my home, and my WiFi is very actually very strong and stable. This reminds me that I need to contact Octopus regarding the IHD issue. I’ll also a look at what you mentioned about the data for the immersion…etc.

 

[Harry Bloomfield]

Yes I’m beginning to hear more and more bad things regarding the electric radiators. I have admit that Dimplex seem to be efficient but as I’m so new to this kind of thing, I’ve lived here since May and only begun to turn them on in the last few days, much to my anxiety given the concerns I’ve read elsewhere online about storage heaters and the high bills, but so far I’m being charged £2.75 to £3.81 per day since Thursday (when I first turned them on), today has reached £4.29.

As I said, there are no higher, or lower efficiencies, all electric forms of heating, are 100% efficient. All that varies, is the cost per unit. Your storage heaters, make use of cheaper power to charge up, then release that heat during the day, when it is needed. The problem is, you may not actually need all the heat they have collected.

If you swap them for none storage heaters, then you will be paying the full rate for your electric round the clock, as well as for your water heating - it's just not worth having E7, just for water heating. To make E7 cost effective, you have to be able to make good use of it, with storage heaters. The full peak rate is 20 to 26p per Kw.

I'm on Octopus's Tracker tariff, paying 15 to 20p Kw for electric, and around 5 to 6p Kw for my gas.

Yes I do, but the IHD often loses signal, no matter where I put it in my home, and my WiFi is very actually very strong and stable. This reminds me that I need to contact Octopus regarding the IHD issue. I’ll also a look at what you mentioned about the data for the immersion…etc.

Ask Octopus for one of their pink gadgets, they work much better than the IHD and give you instant values, if you have wifi.

 

[StephenStephen]

As a couple of other posters have suggested, your starting point for more cheap hot water is:

" Harry suggests, under the black covers of each of the elements (!!! isolate the mains before opening !!!) will be a thermostat that could be set a tad higher for hotter water (which then presents an increased scalding risk) that might do a tad better at filling a bath? "

 

[LeeFL]

These were the settings that I found on them all which I’m assuming was set by the previous tenant.

 

[LeeFL]

As a couple of other posters have suggested, your starting point for more cheap hot water is:

" Harry suggests, under the black covers of each of the elements (!!! isolate the mains before opening !!!) will be a thermostat that could be set a tad higher for hotter water (which then presents an increased scalding risk) that might do a tad better at filling a bath? "

Yes definitely need to do this!

 

[LeeFL]

Don’t know how helpful this is, but attached is screenshots of the octopus app’s usage dashboard over two days: Friday 24th and Saturday 25th (showing as ‘Yesterday’ at the time of screenshot)

24/10/25: 19.01 kWh (£3.78)
25/10/25: 29.18 kWh (£5.22)

 

[dilalio]

Be aware that if the immersion stats are set low and you raise them to 60/65° then your electricity costs will increase also.

But it's always going to be a balance between cost and comfort - such is modern life.

 

[StephenStephen]

Looking at the Octopus readings, it looks like you're on a fixed tariff, rather than a time of use tariff like economy 7.

If that is the case, then a change of tariff will help, especially if you have storage heaters. You'd then just set the water heater and the storage heater timers to come on during the cheap period.

Can you post a screenshot of your octopus tariff that shows the price per kWh?

Is economy 7 still an available tariff?
You might look at Octopus flux as an alternative, if it's not...
...though you'll need to think about how to avoid using much power in the expensive 4pm till 7pm flux peak time if you do that.

 

[StephenStephen]

Be aware that if the immersion stats are set low and you raise them to 60/65° then your electricity costs will increase also.

But it's always going to be a balance between cost and comfort - such is modern life.

...unless setting the thermostats higher effectively shifts electricity use into a lower rate time of day, by reducing the need to boost at high rate times.

 

[Murdochcat]

One thing you need to check is does the water get heated by the lower immersion? Sounds like it’s heated by the top immersion

And do you have E7?

 

[Rodders53]

No I don’t own or part own the flat, I’m renting via Clarion Housing Association.

Then you can't change the storage heaters. They are not your property and would need to restore the flat to 'original condition' when moving out.

Same goes for the shower pump suggestion; permissions may be sought but they may require a 'trusted trader' to do the work? Same goes for the electric shower install - and that'd be hundreds of your pound to benefit the HA.

Complain about lack of shower suitability - and, possibly, the lack of hot water capacity (once you've checked the bottom immersion is in use properly).

so far I’m being charged £2.75 to £3.81 per day since Thursday (when I first turned them on), today has reached £4.29. Given the continued rise in Gas, I’m being told by those around me I’m worrying too much about it and it’s likely going to be not ‘far off’ from what central heating costs would be, proof will be in the pudding of my Oct-Nov bill, I’m on a fixed E7 tariff with Octopus.

Do NOT use the cost - use the kWh (kiloWatt-hours) consumed please... 1 kWh is one unit of electric and is then easily compared to other energy forms.

If on E7 there will be two rates Day and Night one higher (e.g. 30p/unit) and the other lower (e.g.7p/unit)

Yes I do, but the IHD often loses signal, no matter where I put it in my home, and my WiFi is very actually very strong and stable. This reminds me that I need to contact Octopus regarding the IHD issue. I’ll also a look at what you mentioned about the data for the immersion…etc.

That may be due to the meter location and distance from it... If say the meters for the flats is in a basement cupboard.
Octopus might have a solution (or not yet) -- eg https://octopus.energy/help-and-faqs/articles/smart-meter-booster/

Smart meters do not use the home WiFi to communicate, but a Home Area Network (HAN). See https://www.smartme.co.uk/how-they-work for more detailed info.

 

[Madrab]

Same goes for the shower pump suggestion;

An inline shower booster is small beer, nothing like a proper shower pump and it's really easily removed when leaving without any obvious signs apart from a small section of replacement pipe.

 

[Harry Bloomfield]

Looking at the Octopus readings, it looks like you're on a fixed tariff, rather than a time of use tariff like economy 7.

Well spotted! Those screen grabs show you seem to be on '12 month fixed', it's going to cost you a fortune, come the cold weather. This is what you should be on, I think they can switch you remotely - https://octopus.energy/help-and-faqs/articles/what-is-an-economy-7-meter-and-tariff/

Smart meters do not use the home WiFi to communicate, but a Home Area Network (HAN). See https://www.smartme.co.uk/how-they-work for more detailed info.

Actually, they can, or Octopus's pink gadget does, to instantly send your consumption figures to Octopus.