# DEWA Water Heater



## noisyboy (Nov 13, 2011)

Hi All,

So given that I am new here, I've been hearing different things about this water heater which I never had to worry about in Canada.

Some people tell me that they keep it on all the time no problems. Some people tell me that I would be crazy to keep it on all the time because my electricity bill will double and triple.

It is kind of annoying to have to turn it on, wait, shower, then turn it off. I live in a one bedroom apartment. 

Can anyone shed some light on how much this affects my bill? Whether it's on or off? What do you guys do?


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## Vetteguy (Jan 3, 2010)

I live in a 1 bed apt. in JLT and I leave my water heater on 24-7 except when I go back to the USA on vacation.. My DEWA has never been over AED 200/month in over 2 years...

Lave it on so you have hot water now when you need it ....Not 30 minutes from now..
just my .02 cents


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## ziokendo (Jan 7, 2012)

noisyboy said:


> Hi All,So given that I am new here, I've been hearing different things about this water heater which I never had to worry about in Canada.


It's not like a water heater is different in any part of the world.

The natural gas ones (cng/lpg, the kind that probably you had in Canada) provides heat "on the fly", because they can develop more power. So they will consume fuel only when you actually use hot water.

The electrical ones are just a tank with an eletrical heater inside, they heat water exactly like your washing machine does. You have a tank full of hot water, as soon as you use hot water cold water enters in the tank to keep the water level even and lowers the average temperature of the tank.

People tend to believe that leaving a water heater on all the time will consume more energy: truth is that even turning it off, leaving a semi-hot water tank cooling down is a waste of energy.
The power needed to bring a full cold water tank to the desired temperature every day will be almost the same that is needed to keep an already hot tank of water still hot.

So I believe that the elec. consumption for an average regular use will be very similar either turning it on and off, or leaving it on; the latter option being more confortable.


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## Engineer (Jan 13, 2012)

Leave it on all the time apart from when you leave to go on holiday, it is cheaper that way.


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## fcjb1970 (Apr 30, 2010)

Laws of thermodynamics are the same here as in the UK


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## Engineer (Jan 13, 2012)

> Laws of thermodynamics are the same here as in the UK


Correct!


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## noisyboy (Nov 13, 2011)

Engineer said:


> Correct!


Hi All,

Thank you for the responses. I am sure that the water heater I was using in Canada is similar to the one here. When I say I didn't have to worry about the water heater I meant that we never switched it on or off because there was no button. It was just constantly on.

Laws of thermodynamics are the same everywhere I am sure, but I highly doubt that the rate they charge per KWh is the same! I always heard that utilities are expensive here, and when I saw the on/off switch, it kind of made me think the off option was there for a reason; to save on energy and to save on the bill.

Anyway, thanks again. So you guys are 100% certain that it's better to keep it on for a) the environment and b) my bill?


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## ziokendo (Jan 7, 2012)

noisyboy said:


> Thank you for the responses. I am sure that the water heater I was using in Canada is similar to the one here. When I say I didn't have to worry about the water heater I meant that we never switched it on or off because there was no button.


Ah ok, in Italy for example eletric ones are only in 30+ years old buildings because the gas ones are way cheaper and can provide unlimited supply of hot water, so for some reason I assumed that in a cold place like canada this kind of heater would be common.



> Anyway, thanks again. So you guys are 100% certain that it's better to keep it on for a) the environment and b) my bill?


If you want to be really technical about that and achieve 100% certainness, you would have to consider how many times you need hot water each day and how much water, in what room the heater is, what is the temperature of that room and how good is the insulation of the hot water tank, what is the temperature of the water coming from the cold tap, etc etc.

For a common usage average pattern my answer would be yes, just leave it on.

I can imagine some very specific situation where it would be slightly better to turn it on every morning with a timer one hour before waking up and turning it off immediately before use: ie, you live alone, you use hot water just once a day (morning shower) for the full tank capacity, and then you are outside home not using it, the heater is not so good quality/insulation and is installed in a cold environment, etc


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