Immersion heater timer or leave on 24/7

Derekbirmingham

Hello peeps.
i have a bog standard immersion tank with the heater in the top.a chap at work told me its best off leaving the heater switched on and the stat will keep the water hot as needed and this was the cheapest way of running this heater.
i was thinking of replacing the immersion on/off switch with a timer off amazon.
and switching it on at let say 5am to 7am then off,for daytime hot water.and then on at 4pm to 6pm for a bath.
Does this sound about right or leave it on 24/7.I ave no boiler or central heating.
thanks

Hasbeen

Sounds about right.

But you will get more expert replies by posting in the Energy Board ? Rather than here in the water bills??

Talldave

A timer is a very good idea - although make sure it's a dedicated immersion heater timer designed to handle the high current load.  If you pay a bit more, you could get one with a boost button.  Then you might find you don't need the afternoon top-up every day and could just hit the boost button an hour before you want a bath if it's needed.  Is the tank well insulated?  You might be able to improve the insulation to help it hold it's heat for longer.

Also, are you on an E7 meter/tariff?  If water heating forms the bulk of your electricity consumption, you would probably find that an E7 tariff is more economical, heating the water as you suggest, just before the cheaper night rate ends (check the hours for your area and double-check whether the hours move with GMT/BST or not)..

Robin9

Others will know -  how long would you need to have the I/H on to get a tank of hot water when you've only got a single element at the top ?

Derekb - if you do have E7 then it might be better to have your bath before 0700

tim_p

Robin9 said:

Others will know -  how long would you need to have the I/H on to get a tank of hot water when you've only got a single element at the top ?

That would depend on the size of the tank and the length of the immersion, along with the chosen tank temp set on the ‘stat. Ours is a small 117l tank with a 27” 2.7kW element at the top pointing (!) down into the tank. A single shower takes around 1kWh to get back to ‘hot’ (approx 60 degrees)

Derekbirmingham

Mine is a standard size tank with 22 inch stat i think.thanks for the messages.
the stat is set to full 70.
also i dont think im on e7
im with npower and am in a contract Superfix june 2021 v2 elec dd. 

avoidtheupsidedownbottles

That tank looks like 120 litres which will heat up by about 22 degrees C per hour.  So it should heat up in a couple of hours if water is at room temperature to start.  
Since the insulation is hit-and-miss, it would definitely be best to only heat it up before use rather than leave on all the time.

Talldave

There is normally a cover over the top of that immersion heater isn't there??

Mister_G

I do hope so, from a safety point of view!  That's an exposed live terminal there!

Cardew

70C is hotter than most people need. 55C will be more economical.

Your insulation is old fashioned and not very effective - all new(last 20 years?) cylinders come with much more effective foam insulation.

As said above, you MUST get a cover over the wiring - it is lethal.

Richie-from-the-Boro

E7 - "think" inadequate "know for fact" is needed.my friend ! Old school lagged cylinder is poor, new PartL standard cylinder with bottom only element is 3 times more energy efficient Screwfix is your friend. If you are E7 a full Hortsmann water controller about £80.  Wiring terrifies me and should be on 20a ring CU. Legionaries protection is dormant below 20°C and do not survive above 60°C - gov UK.

Best of luck.