Energy consumption of appliances

[Graeme]

I live in a modern 2 bed flat with all electric heating. With an electric shower, I have no real use for instant hot water, other than to fill the kitchen sink for washing dishes each evening.

I have been starting to wonder if turning on the 2x 3Kw immersion water heater with a 120 litre capacity for one hour each evening is being energy efficient, just to fill the sink with 8-10 litres of hot water.

I have been considering is the purchase of a 3.5 litre whistle kettle which would take 15 minutes to boil with the electric hobs largest ring on full. Also the cooker hood fan would need to be on for the duration. This is still not enough hot water though so would also need to fill my existing 1.5 litre electric kettle for 3 minutes to boil.

Would I be better better off (energy consumption wise) continuing to use my immersion heater or opt for the kettle option?

Thanks!

 

[foxhole]

My dishwasher only uses 6litres of water and does not need to boil any of the water, hand washing can be very inefficient. My immersion will produce enough hot water to fill a sink in 15mins [3kw], why do you run yours for an hour?

 

[freddiemercurystwin]

Why not just use an electric kettle? Its only a few pence each time if that.

 

[Graeme]

Hi,

I remember discovering once that the water was not hot enough after half an hour so have run it for an hour ever since. You have got me thinking that perhaps the tank was completely cold on that occasion so running it for an hour each night is not necessary. I will try 15 minutes tonight, thanks!

 

[Graeme]

That is what I have been considering freddy but to get the water to the right temperature requires a minimum of 5 litres boiling and I cannot seem to find a kettle online which holds that capacity.

 

[Dave54]

Years ago we were stuck for space with a small holiday let, and had something similar to the ones shown here fitted for the hot water.
http://www.aquahot.co.uk/water-heaters/in-line-instantaneous-electric-water-heaters.html
No connection to me there incidentally, IIRC we sourced ours from a local electrical shop.
Not the greatest flow depending on how hot you wanted the water, but useable. It worked a treat.

ETA I had another thought, many years ago we had a wall kettle, a Creda Corvette IIRC. Looks like there are still similar things available, but not cheap!

 

[Graeme]

Thanks Dave, I looked at them both but the cost of circa £150 then paying an electrician to wire direct to the circuit board makes me wonder how many years it would take to recuperate that money from saving on my energy bills and by that time the unit would probably be due for failure!

Why they build new flats with a bath (which I have never used and never will) with a 120 litre storage tank when the ideal size of tank I would ever need is 20 litre maximum and that would also provide another whole cupboard for storage!

 

[big-all]

you should only need around 2.5-3L off boilng water mixed with 2l off cold to give you enough water to fill a washing up bowel

just start with 1L cold and a kettle full
refill the kettle and reboil by this stage youve done several plates just before refilling with hot so will have dragged the temperature down a bit
and remember to swill the kettle out with a cup off cold water to draw the last hot water/heat from the kettle

 

[scbk]

If you've got electric heating do you not have some form of off peak electricity?

 

[Graeme]

Nice tips there thanks big-all. I've been using the bare sink all this time so will get a washing up bowl which will have obvious advantages.

No off peak heating here scbk, there is just a single meter at the circuit board.

 

[big-all]

make sure you scrape your plates after each meal
leave any pans to soak in cold water for 10 to 20 mins if nesiserry
just an inch in the bottom swilled round the sides and empty before washing

you will get roughly 6 plates and cutlery 5 or6 bowls several cups and 2 pans
before the water get to mucky
wash your plates and cutlery as well as bread knives or anything used to cut raw food first as they need heat as well as water to kill the germs
cups mugs pots and pans towards the end when the water will be cooling as these items will be abouve 70% in use either on the cooker or with hot water

 

[ladylola]

We don't have a dishwasher so can't personally comment on their use or energy consumption but here's someone who possibly has more time and has done the calculations
http://growingthingsandmakingthings...1/are-dishwashers-more-efficient-than-my.html
As it says several variables and it does point out to anyone of a cynical nature that the report that came out on the side of the machines was sponsored by Bosch , Electrolux and others .

 

[EightyTwo]

Dishwashers are efficient if they're full.

The electric kettle will be more efficient than the immersion heater as you will use ALL of the water you have heated. It will also be more efficient than the hob as the hob has to heat itself as well as the kettle (unless it's an induction hob) and a lot of heat will go past the kettle and into the air (and out through the extractor?). A microwave oven heats water very efficiently but it will be a bit slow.