Truth About Switching Geysers Off?

[Fuzzbox]

So if you were saving 8 units a day @ lets say R2 per unit.
That amounts to an approximate saving of about R480 per month.
That is a meaningful amount.

Also when a geyser is turned off it takes about a day to cool down because they are pretty well insulated.

I have been turning my geyser off for about 10 years.
They geyser was accounting for about 30% total usage.
Went from about 1100kw per month to an average of about 850kw per month.

Geysers also dont have to be set to 65 degrees when 55 degrees is still damn hot.

 

[Zoomzoom]

Do you have access to the geyser or the electrical cable leading to it? If so, you can attach a clamp-on meter to it to see exactly what kind of daily consumption you have. Hardware stores should have them.

honestly - no - wouldn't know where it was, don't want to spend R's I haven't got on a meter to use once when I can ask people who have tested it out.

 

[Zoomzoom]

So if you were saving 8 units a day @ lets say R2 per unit.
That amounts to an approximate saving of about R480 per month.
That is a meaningful amount.

Also when a geyser is turned off it takes about a day to cool down because they are pretty well insulated.

I have been turning my geyser off for about 10 years.
They geyser was accounting for about 30% total usage.
Went from about 1100kw per month to an average of about 850kw per month.

Geysers also dont have to be set to 65 degrees when 55 degrees is still damn hot.

See this is the problem - already two people have said 'yes I do it and it saves' against people who say 'the maths proves it doesn't' === WHICH IS IT FOLKS?

FYI your geyser must be insulated incredibly well - if I switch my geyser off at night it is ice-cold by morning and if I leave it on, it's appreciably colder in the morning than after I've used it for the first time and it's heated up i.e. no-one showers until the water has been run for few minutes first thing to get it properly hot.

 

[Chingha]

We tried it and it saved R60 off our previous bill but there are so many variables as to make that meaningless. We concluded that it was more hassle than it was worth.
I suspect that savings revolve alot around how much hot water you draw, when hence the variances in results.
Remember to keep the geyser at above 55 degrees to kill goggas

 

[Sinbad]

See this is the problem - already two people have said 'yes I do it and it saves' against people who say 'the maths proves it doesn't' === WHICH IS IT FOLKS?

FYI your geyser must be insulated incredibly well - if I switch my geyser off at night it is ice-cold by morning and if I leave it on, it's appreciably colder in the morning than after I've used it for the first time and it's heated up i.e. no-one showers until the water has been run for few minutes first thing to get it properly hot.

Then you will save more money by insulating your geyser properly.
Mine drops like 3 degrees overnight. And it's outside.

 

[genetic]

I see no noticeable difference in switching my geyser off than leaving it on.

Switching it on for an hour a day uses as much power as just leaving it on.

 

[bekdik]

So if you were saving 8 units a day @ lets say R2 per unit.
That amounts to an approximate saving of about R480 per month.
That is a meaningful amount.

Also when a geyser is turned off it takes about a day to cool down because they are pretty well insulated.

I have been turning my geyser off for about 10 years.
They geyser was accounting for about 30% total usage.
Went from about 1100kw per month to an average of about 850kw per month.

Geysers also dont have to be set to 65 degrees when 55 degrees is still damn hot.

It's all dependent on the amount of hot water used. If you turn the geyser off and don't use any water, then over a few hours, the temperature will be maintained and when you switch on again it only needs to add a small amount of energy to heat up to cut off temp.

On the other hand, if you use the hot water it will be replaced from the cold water supply which will cause the overall temperature to drop significantly which in turn will cause the geyser to consume a lot of electricity as it heats up to the cut off point.

 

[Masataka]

We only use ours once a day, and that's in the morning, so the geyser only gets switched on once at night and is left on until it's finished heating, then it goes off and is still very hot for a morning shower.

This saves us a couple hundred rand in electricity each month, but I can understand that for houses who use the geyser in the morning and at night that leaving it on could be more efficient.

 

[KleinBoontjie]

Me and the wife did an experiment a few years back. We recorded the readings on the meter and left it on for a month. Recorded again and the next month we switched in on at 4pm and off at 7pm every day. There was a noticable difference. Back then our bill came down by R200.
Did more experiments, changed all my bulbs in the house the following two months, to LED's. Don't know how much we saved just on that, because my old deep freezer broke and I got an A-energy rating one. With that and LED's, we knocked down +/-R200, again.

 

[Nirv]

My scenario is like this. Two people in a flat, showering directly after one another in the evenings. Our current approach is to turn it on by 16:30 to allow it to get to full temperature by 18:00 when the municipality device switches it off, then leave it off until the next day. The geyser is located inside a cupboard. We usually shower shortly after 18:00. The other night i did the usual 1.5hr on time, then made food etc until 19:30 and decided to shower. Somehow the geyser had lost enough heat to be lukewarm in 1.5hrs after 1.5hrs of heating, and i just barely managed a k*k shower. It's hard to believe that it can be this badly insulated, it isn't warm to the touch when the water is hot. I've tried leaving it on all day before and saw we'd lost about 15kWh, as opposed to about 5 if we do the 1.5hr thing. So not an option.
So it seems it needs more insulation, but I've mostly been told geyser blankets are largely ineffective. So I dunno...

Oh and we strictly only use hot water for the shower. We boil water for the dishes too. So there's nothing else using the water.

 

[krycor]

It's the only reason I have an electricity bill of avg 350 a month besides extensive use of CFL and LED lighting and appliances that are ultra efficient. I've tried without timing the geyser and the cost goes up fast this I've installed timers at ever apartment I've moved into with owners permission of course (and then they shocked with how low my elec consumption is compared to others).

A few things I've noticed over the years is..
1. Electric blankets.. If the geyser has this timer switch is very effective and can literally reduce time to 1x 1.5hrs all year. If not in winter I have to bump up to 2x 1-1.5hr (so 2-3hrs) slots due to heat loss. Considering buying a geyser blanket for next place if they don't have simply due to cost savings I make longer term(if staying longer than 1yr).

2. Location of geyser makes a difference.. Outside can be a blessing in summer but a problem winter.

3. Most geysers get entire tank ready in 45-60 min from cool. Learn what yours is and factor in that u want to use your shower during the time the geyser is on. So eg I shower during the time the geyser runs and let it run 20-30 after such that I have a hot tank to last till evening when either I turn on for 30 min at 4 or 45 min at 9pm(post gym shower). Again factoring cooling times etc. basically you need to figure out your usage and model it accordingly.

3. Larger families might struggle by my parents use to run 3, yes 3.. Geysers this way with the kitchen cycle varying radically different from theirs or ours.. Again totally dependent on usage models. Solar helps with daytime heat retention. And reduces time to hot.

Nowadays they have two geysers which are linked to a solar reheat.. And kitchen and cleaning ladies quarters fed thru a insant heat solution too

 

[etienne_marais]

In our case, a definite saving. Two people in flat, 150L geyser. Switch on before going to bed and off when leaving for work.

 

[JJ101]

I don't have any scientific facts but I've tried it and it seems to save me electricity. Just my experience.

 

[Arthur]

People who claim noticeable savings from switching off a normal 100-300 litre domestic geyser are either not measuring correctly, or their large geyser has zero insulation (extremely unlikely), in which case bigger savings are to be had were they to insulate the geyser.

There is no way the current configuration of the universe allows one to save energy by bringing water to a certain temperature (say 60 degrees), letting it cool, and then heating it up to that temp again.

I'm on a phone and can't now type out the maths. But maybe an engineer will. All you need is Grade 9 physics.

It takes a precise amount of energy to raise the temp of say 150 litres by say 10 degrees. There's no way around that. Period.

If the claims were real, one must account for the loss in energy to that extent, even allowing for <100% efficiency in heater element and dissipation from geyser.

All else being equal, if the claims were even vaguely true then science as we know it collapses completely.

 

[emptybruwer]

I am saving about R300 pm after installing n timer. I highly recommend getting 1

 

[DA-LION-619]

It depends, if you only need hot water for bathing in the morning and evening you're going to notice a saving.

 

[Arthur]

I am saving about R300 pm after installing n timer. I highly recommend getting 1

That's because you're using less hot water. You'd be hard-pressed to show any measureable savings if you heated the same amount of water, because the only significant loss is heat dissipation/loss from the geyser to the atmosphere.

 

[Arthur]

It depends, if you only need hot water for bathing in the morning and evening you're going to notice a saving.

Not really. If you use the same amount of hot water, it takes the same amount of energy (hence units of leccy) to heat it. Usage aside, leaving your geyser powered on only replaces the energy lost through dissipation, which is a function of how insulated your geyser is.

People who report savings are getting them mostly by reducing their hot water usage, and that saves energy. If the number of hot litres stayed the same, you wouldn't really measure any appreciable saving.

 

[DA-LION-619]

Not really. If you use the same amount of hot water, it takes the same amount of energy (hence units of leccy) to heat it. Leaving your geyser powered on only replaces the energy lost through dissipation, which is a function of how insulated your geyser is.

What if you factor in that when using a timer, that you're not heating the water to a certain degree of temperature but just for an amount of time.

 

[Arthur]

What if you factor in that when using a timer, that you're not heating the water to a certain degree of temperature but just for an amount of time.

you only need to heat cold water that replaces the hot water you used, and top up the loss though dissipation/heat-loss. You don't need to heat water that's already hot - that used zero units.

If your geyser loses 3 degrees during the day, then the usage is only the units it takes to heat that amount of water by 3 degrees. It cannot possibly be more. And if you switch off, you still have to recover those 3 degrees, so zero saving.