Cheaper to use kettle and electric shower instead of immersion???

annoye

Hi, i'm going to be moving into a one bed in the next month or so... it has no economy 7.... It's a friends flat he just bought. Currently the hot water system is an immersion heater on a normal day rate tariff... The shower he has just put in, is one that just plugs onto a mixer tap.... He is doing the flat up currently, but i am trying to figure out how much it's going to cost me to have hot water... It will only be me there.....

My theory, is that it will be cheaper for me to have an electric shower instead... i shower twice a day mon-friday.... weekends once-twice a day. And i am no longer than 10minutes per shower.... i like showers to be hot, but not boiling... average around a 7-8 heat setting on most shower systems i have used.... so that is 20minutes of showers per day......... I will only wash up once a day too... so i'm thinking boil a kettle, once, or maybe twice depending how big a bowl i need to use...

Will this be alot cheaper for me, than having an immersion heater heating up the water?? I see the benefits of having the immersion for bigger familys etc... but just for a single person in a one bed flat, it seems to be a waste to me?? I am not sure if i am thinking correctly though

thanks

Cardew

The actual cost of the water heated and used will be exactly the same.


The main factor to be considered is any losses from the hot water tank and pipes. With a modern well insulated HW tank these losses are low - around 1kWh to 2kWh a day. In any case for much of the year that heat isn't lost as it warms the fabric of the house.


To have a decent electric shower fitted is not cheap unless the house has been already pre-wired. For a decent shower you need heavy duty wiring and RCD(fuse)


As for boiling water in a kettle for bowls of water! This is 2014 - perhaps you should get some stones and go down to a local river to wash your clothes.;)

Pincher

annoye wrote: »

Hi, i'm going to be moving into a one bed in the next month


He is doing the flat up currently,


It will only be me there.....

Get a tarpaulin. Create a small pond in the middle of the room. Wash out of a plastic bowl.
It's easy to bail out the water into the bowl afterwards, to throw out the water in the street. The tarpaulin can be rolled up when they come and lay the carpet.

annoye

lol. i know its old fashoined... but seriously, the way im seeing it... 3kw immersion heater, 3 hours to heat up water = 9kw usage.....

8.5kw shower, 20minutes a day= 2.8-3kw...... boiling a 2kw kettle, 3 minutes = 0.1kw......

so immersion heater =9kw to get hot water.... shower and kettle =2.9kw... thats 1/3rd of the cost


Now, i know the immersion wont be going from cold to hot everytime.. but lets say every 1 hour, the temp has dropped and it turns on for 5mins to heat back up.... over a day thats still 6kw used of electric....

It depends how much heat would be lost worse case scenario.... he is a typical landlord, hes spending as little as possible, so the tank will be the same old tank it was when the place was built... And he's doing it up, but only for a quick rental..... he plans to change the layout later on, but i have said i would prefer electric shower... we both do up property so running the wiring and pipes is not an issue at all, and we both know sparkys that can wire up to the fuse board so the cost of fitting one is going to be low.

If i can get the immersion heater to warm up less than 1 hour a day, it would be cheaper for me than a shower and a kettle i guess??? If my theory and maths is correct??... but i'm not sure if that's possible with an older system???

comeandgo

It's the ten minute showers that I can't understand. What do you do for the last five minutes as surely you can't still be lathering.

annoye

comeandgo wrote: »

It's the ten minute showers that I can't understand. What do you do for the last five minutes as surely you can't still be lathering.

lol i stand there for 5 minutes waking and warming up before i start to clean myself.... All my friends will spend 15-20mins in showers.. they cant believe how quick i am when i go for one

macman

You don't grasp the basic laws of thermodynamics: it costs the same to heat the same amount of water from temp x to temp y whether you use a kettle, an immersion heater, or any other water heating device powered by single rate electricity. They are all the same efficiency: 100%.
If you wash with the contents of a kettle, then yes, it will cost less, but only because you use far less water.
As Cardew explained, the heat loss from a properly insulated hot tank is minimal. Any marginal running cost saving from an electric shower would be offset by the years it would take to recover the install cost.

Cardew

annoye wrote: »

lol. i know its old fashoined... but seriously, the way im seeing it... 3kw immersion heater, 3 hours to heat up water = 9kw usage.....

8.5kw shower, 20minutes a day= 2.8-3kw...... boiling a 2kw kettle, 3 minutes = 0.1kw......

so immersion heater =9kw to get hot water.... shower and kettle =2.9kw... thats 1/3rd of the cost


Now, i know the immersion wont be going from cold to hot everytime.. but lets say every 1 hour, the temp has dropped and it turns on for 5mins to heat back up.... over a day thats still 6kw used of electric....

It depends how much heat would be lost worse case scenario.... he is a typical landlord, hes spending as little as possible, so the tank will be the same old tank it was when the place was built... And he's doing it up, but only for a quick rental..... he plans to change the layout later on, but i have said i would prefer electric shower... we both do up property so running the wiring and pipes is not an issue at all, and we both know sparkys that can wire up to the fuse board so the cost of fitting one is going to be low.

If i can get the immersion heater to warm up less than 1 hour a day, it would be cheaper for me than a shower and a kettle i guess??? If my theory and maths is correct??... but i'm not sure if that's possible with an older system???

As I said in the earlier post, using the immersion, or using the shower/kettle costs exactly the same for the water you use. The only consideration is the amount of heat you lose from the Hot Water tank.

Now, i know the immersion wont be going from cold to hot everytime.. but lets say every 1 hour, the temp has dropped and it turns on for 5mins to heat back up.... over a day thats still 6kw used of electric....

That statement is just nonsense and it IMO you are just plucking figures out of the air to justify a case.

Firstly with your 'reasoning'(I use the term loosely you are making the assumption that the immersion heater will be on 24/7.

Secondly Hot water tanks are tested to a British Standard(BS) where the heat loss is measured over a period of 24 hours with the water at 65c. Typical losses are between 1kWh and 2kWh in 24 hours(you can find the figure stamped on your tank) - in practice it will be less than that figure.

dippydolly

If you are not happy, why not try doing it one way for a couple of weeks, then do it the other way for the same amount of time. Your answer may not be perfect, but at least you will have a good idea of what works for you. Good luck.:j

annoye

Cardew wrote: »

That statement is just nonsense and it IMO you are just plucking figures out of the air to justify a case.

Firstly with your 'reasoning'(I use the term loosely you are making the assumption that the immersion heater will be on 24/7.

It isnt nonsense? if it heats up to temperature, and an hour later drops, and takes 5 minutes to heat back up.... theres 24 hours in a day,so it will happen 24 times... 24X5.... which gives you 120minutes a day it is actively heating up water.... divide 120 by 60, gives you 2 hours.... 3 kw an hour x 2 gives you 6kw every 24 hours...... Yes in your original post you state that "With a modern well insulated HW tank these losses are low - around 1kWh to 2kWh a day"

but as i stated in my second post, it is not going to be a modern well insulated system as far a i can see.... it will be a bog standard 1970s style system... so i can only assume that it will lose alot more?


And if it isnt on 24hours a day, then yes it wont happen 24 times like in my example... but then if it still lost the same amount of heat through that period. it will take maybe 20minutes to heat back up, instead of the 5 minutes... so it will still be roughly the same?

i will have to see have a look at the tank and see if it has anything printed on it.

annoye

so if i read this correctly... the cost of the water used, will be exactly the same, using an immersion heater, than it would be using a kettle and a shower....... but, the immersion heater will lose 1-2kw a day on average..... so the immersion heater will be dearer to RUN (not counting installation) than just using a kettle and shower.... and it wouldnt matter how long was spent in the shower, if it was an equal amount of water used in both scenarios, it would still cost the same??

so that means that it will be cheaper to use a kettle and electric shower, as oppose to using an immersion heater?? Due to the immersion heater losing 1-2kw of heat a day