Nest or Hive vs Immersion water heater

19
Posted 18th Oct 2018
Will any smart thermostat work with my immersion water heating system ?

My water cylinder looks like this. (Below)

Looks like it is constantly on. Bill is sky high. Anyway to reduce this ?

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Are you on economy 7 ? if so there should be 2 heating elements. One at the bottom which heats up the whole tank during the "cheaper hours" , the second near the top which enables you to heat a smaller amount of water at any time .

Both heater elements should be on separate switches with red indicator lights , the bottom element switch could be at the back of your tank cupboard (not immediately obvious ) and should be permanently on - unless you are away for a day or more .

The other switch should be visible and readily accessible and should normally be off unless you require a "top up " of the hot water you have heated on the cheap rate the previous night.

If your lower switch is turned off and your upper one turned on you will be permanently heating the water and that will cost you a fortune !
Agreeing with what has already been mentioned by the folks above in that you should try and figure out what is causing the emersion to be switched on.

After you figure out where the switch is, I would suggest getting a basic timer fitted in place of the on off switch so you can at least set a schedule for when the hot water is generated. A smart thermostat will do nothing for you in this scenario.
You guys comments are soooo useful. I didn’t know any of that before. I’m glad people are so helpful here :). Thank you. Let me attach pic of two switches on the wall and get back to you.
Firstly thanks so much for helps so far. Based on above pic, I have following questions please.

1. How easy is it to put timer ? Is it DIY job ? At the moment bottom switch is stuck. Both switches are on all the time (not sure if it is best practice).

2. Regards to question “Is it Economy 7”? I really don’t know and I don’t think so. I am paying per unit charge for electric tariff. This is new flat without those heat storing heaters in rooms.

3. So instead of putting timer, putting Hive/Nest thing won’t benefit me ? Apart from being able to turn on and off hot water from app of course.

4. In summer when we don’t need hot water, can these switches be turned off completely ? I didn’t know what to do and left on whole summer
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Well that's why you are getting such huge bills (if they are both switched on ) .
Most important starting point find out if you are on economy 7 . By :-

a. Check your bill (either online or a paper bill ) If on Economy 7 there will be 2 readings for electricity.
b. Check your meter - there will be two readings for electric if on economy 7 (you may have to push a button by the display -mine's a blue button which cycles through readings and date on the display ) .

You must positively find out if you are on economy 7 - it makes a world of difference to how you should heat your water (the cost that is !) . If you aren't sure then contact your supplier they will know . Not having storage heaters does not necessarily mean you are not on Economy 7 .

If not on economy 7 remove the fuse from the "bottom " stuck switch ( to be double safe turn off your mains power first at the fusebox (consumer unit ) - prise the fuseholder out using a straight bladed screwdriver and remove the fuse . This will disable the bottom immersion heater and allow you to control the heating of your water via the top switch .

If on economy 7 leave the stuck switch on (it will only heat the tank for the 7 "cheap" hours ) and leave the "Top" switch off as this will heat the water 24 hours a day - just use it sparingly to heat the water if you have used a lot of hot water and need a little more .

How it is controlled and what rate it is on will make all the difference . It looks like you have a thermostat on the tank (that wire coming out just to the right of the "Joule" logo - that wire should lead to a control unit / timer that should switch the bottom immersion heater on/off dependant upon the settings ? - maybe follow that black wire and see what's at the end of it . If it is a control unit it should have the facility to vary the temperature and time the immersion heater is on (it could even be in a different room ).

I'm not a qualified electrician (so not sure what you can legally do these days ) but I would feel comfortable (as a DIY er) replacing the stuck switch unit and tracing where the thermostat wire (I think that's what it is ) goes and working it out from there .

If you are totally clueless about electrics (I mean no disrespect - some of us are ) I would recommend asking a more DIY oriented mate round to look at the set up - its quite possible that correctly setting up the thermostat control unit could slash your bills .

Otherwise get an electrician in to

a Explain how your set up works and the best way to operate it .
b Change the stuck switch ( a 30 min job + £2 ish for the new switch .

Finally back to your original question "can I fit a smart thermostat " - answer is Yes - as it appears to me you already have a thermostat on the tank (by the look from the photo ) . Will it be worth it ? answer probably not - just find out how your current system works and set it up correctly .

Most important (I repeat) find out for certain if you are or are not on Economy 7 . Whether you are or not will change the way you need to use your set up .
Fn6Dragon3 h, 59 m ago

[Image] [Image]



They're switched spur connection units and the switch is there for local isolation, are you sure they're not controlled elsewhere from a timer?
Has anyone established whether this cylinder is fed exclusively by immersion element?

I have a similar cylinder and it has an immersion heater, but is exclusively fed by my gas fired boiler because the immersion switch is off.
moob19/10/2018 13:37

Has anyone established whether this cylinder is fed exclusively by …Has anyone established whether this cylinder is fed exclusively by immersion element?I have a similar cylinder and it has an immersion heater, but is exclusively fed by my gas fired boiler because the immersion switch is off.



Good point , OP says he does not have storage heaters , does he have gas Central heating ? If so the water will also be heated by the boiler which will be cheaper than the immersion ,even in summer when heating switched off (set to HW only or thermostat fully down . More info please @Fn6Dragon .
deleted90213919/10/2018 14:46

Good point , OP says he does not have storage heaters , does he have gas …Good point , OP says he does not have storage heaters , does he have gas Central heating ? If so the water will also be heated by the boiler which will be cheaper than the immersion ,even in summer when heating switched off (set to HW only or thermostat fully down . More info please @Fn6Dragon .


No central gas heating. All electric flat. Thank you.
Why don't you use hot water in the summer?
chocci20th Oct

Why don't you use hot water in the summer?


Too hot.. LOL. Rarely need hot water when I have shower in hot summer months.
deleted90213919/10/2018 09:42

Well that's why you are getting such huge bills (if they are both switched …Well that's why you are getting such huge bills (if they are both switched on ) . Most important starting point find out if you are on economy 7 . By :-a. Check your bill (either online or a paper bill ) If on Economy 7 there will be 2 readings for electricity.b. Check your meter - there will be two readings for electric if on economy 7 (you may have to push a button by the display -mine's a blue button which cycles through readings and date on the display ) .You must positively find out if you are on economy 7 - it makes a world of difference to how you should heat your water (the cost that is !) . If you aren't sure then contact your supplier they will know . Not having storage heaters does not necessarily mean you are not on Economy 7 .If not on economy 7 remove the fuse from the "bottom " stuck switch ( to be double safe turn off your mains power first at the fusebox (consumer unit ) - prise the fuseholder out using a straight bladed screwdriver and remove the fuse . This will disable the bottom immersion heater and allow you to control the heating of your water via the top switch .If on economy 7 leave the stuck switch on (it will only heat the tank for the 7 "cheap" hours ) and leave the "Top" switch off as this will heat the water 24 hours a day - just use it sparingly to heat the water if you have used a lot of hot water and need a little more .How it is controlled and what rate it is on will make all the difference . It looks like you have a thermostat on the tank (that wire coming out just to the right of the "Joule" logo - that wire should lead to a control unit / timer that should switch the bottom immersion heater on/off dependant upon the settings ? - maybe follow that black wire and see what's at the end of it . If it is a control unit it should have the facility to vary the temperature and time the immersion heater is on (it could even be in a different room ).I'm not a qualified electrician (so not sure what you can legally do these days ) but I would feel comfortable (as a DIY er) replacing the stuck switch unit and tracing where the thermostat wire (I think that's what it is ) goes and working it out from there .If you are totally clueless about electrics (I mean no disrespect - some of us are ) I would recommend asking a more DIY oriented mate round to look at the set up - its quite possible that correctly setting up the thermostat control unit could slash your bills .Otherwise get an electrician in to a Explain how your set up works and the best way to operate it .b Change the stuck switch ( a 30 min job + £2 ish for the new switch .Finally back to your original question "can I fit a smart thermostat " - answer is Yes - as it appears to me you already have a thermostat on the tank (by the look from the photo ) . Will it be worth it ? answer probably not - just find out how your current system works and set it up correctly .Most important (I repeat) find out for certain if you are or are not on Economy 7 . Whether you are or not will change the way you need to use your set up .


Hi Sorry for late reply. Been busy lately.

Yes, Just checked my bill. i”m definitely not on Economy 7 heating.. I’m paying following rate.

20p standing charge per day
Electricity unit rate per kWh 12.305p

So, i have decided since it adds little benefit of installing smart thermostat, I will abandon that plan.

If I fit something like MasterPlug 240 V Digital Weekly Immersion Heater Timer amazon.co.uk/dp/B074277H2Z/ref=cm_sw_r_cp_tai_sbG0BbSX03RSS, Wilt it work?

1 ) Since I got two upper and lower heating element/ thermostat, do i need two timers? (Presumably same settings)?

2 ) Wiring wise, From power - take input power feed from cable inside the wall. (Currently it is hardwired to fused switch). To Appliance - One fo those white wire from immersion heater?

Currently as per pictures. Two cables go into two wall Fused switch. Thanks for your comprehensive explanation, Rogparki. I appreciate it.
Edited by: "Fn6Dragon" 25th Oct 2018
Fn6Dragon57 m ago

Hi Sorry for late reply. Been busy lately.Yes, Just checked my bill. i”m d …Hi Sorry for late reply. Been busy lately.Yes, Just checked my bill. i”m definitely not on Economy 7 heating.. I’m paying following rate.20p standing charge per day Electricity unit rate per kWh 12.305pSo, i have decided since it adds little benefit of installing smart thermostat, I will abandon that plan.If I fit something like MasterPlug 240 V Digital Weekly Immersion Heater Timer amazon.co.uk/dp/B074277H2Z/ref=cm_sw_r_cp_tai_sbG0BbSX03RSS, Wilt it work?1 ) Since I got two upper and lower heating element/ thermostat, do i need two timers? (Presumably same settings)?2 ) Wiring wise, From power - take input power feed from cable inside the wall. (Currently it is hardwired to fused switch). To Appliance - One fo those white wire from immersion heater?Currently as per pictures. Two cables go into two wall Fused switch. Thanks for your comprehensive explanation, Rogparki. I appreciate it.



I'll have a look at the timer later . My thoughts at the moment - You indicate you are a light user of hot water, I take it you have removed the fuse from the lower immersion as that will be costing you most of your bill (you don't appear to need a tankful of hot water).
I presume you live alone , so just yourself ? Try switching the the upper immersion on for 30 mins -1 hour it should give you enough hot water for a shower and a sink full for washing up - experiment to find out if you gat enough hot water for your needs and how long you need it switched on for .

If you need the hot water at the same time every day a timer could be a good idea , but if like me you work varying shifts it could be that just switching the upper immersion on an hour before you need it could be all you need to do (Don't forget to turn it off after your shower etc though !!!) .

If you don't need a bathful of hot water the bottom immersion is superfluous (and only serves to multiply your electric usage - keeping water hot that you don't use !) .

Ensure you remove the fuse from the bottom immersion switch to disable it and play about with the upper one (to see how much hot water you get and how long it takes ) . Then decide if you really need a timer or if you are happy to manually switch it on and off as you need the hot water .
Thanks to very good help from Rogparki, I bought this screwfix.com/p/greenbrook-7-day-digital-timer/4157r

To replace this

hager.co.uk/product-catalogue/wiring-accessories/sollysta/white-moulded/white-moulded-fused-connection-units/wmssu83fon/59196.htm

Which was in this condition. Blue cable burned out and disconnected. Plastic melting.


35810283.jpg



While fitting the timer I found out there is no yellow Earth cable connection on new timer. So I use use brown and blue like this referring to user manual comes with timer.


35810283.jpg



Two blue on number 1, live brown from power source on number 2 and live brown from heater cable on number 3.


35810283.jpg

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Problem ! !!! Even though I set the timer to always on, power didn’t go to immersion heater.

What did I do wrong please.

Edited by: "Fn6Dragon" 27th Oct 2018
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Input live is live.


35811209.jpg


Output live is NOT live.


35811209.jpg



Timer is set to always on
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Edited by: "Fn6Dragon" 27th Oct 2018
Problem solved. It was faulty timer unit. Damn. I thought brand new unit supposed to be working. I now got manual timer. It works straight away. Many thanks to Rogparki. Without him I won’t be able to do this kind of DIY job.

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Edited by: "Fn6Dragon" 27th Oct 2018
Connect earth to earthing point in wall box
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