Switching your geyser off, does it save money?

[Zewp]

Me and my flatmate are very conflicted on this. I believe it's actually using more electricity when you constantly switch it on and off, and he believes switching it off works.

We've only got a 100l geyser, and once switched off it cools down rather fast, so it has to reheat from scratch when you want to switch it back on again. I've monitored it and when it's been turned off for the day it easily consumes between 3 and 5 units to heat back up again. Leaving it running during the day seems to have it only use about 1 - 2 units of electricity to keep itself heated.

Our electricity consumption per day used to be about 15 units when we switched the geyser on and off, then last week I started leaving the geyser running and we only used about 10 units a day. My flatmate insists this is pure coincidence and he and his father fights with me because I want to 'waste money by leaving the geyser on'. This really sucks because their solution to 'save' money seems to be doing nothing more than costing us money.

Even if it does actually save money, I wouldn't think it would be more than R50 a month, which is insignificant considering what an inconvenience it is to have your geyser off the whole day. If I want warm water, there should be warm water. I hate having to get up at 6 in the morning to switch the geyser on just so I can be sure there will be warm water for a shower so I can be at class at 8.

Has anybody else tried both switching it off and leaving it on and have you noticed any 'significant' savings?

 

[MickeyD]

I agree with you.

I also believe that switching it on/off shortens the lifespan of the heating element.

 

[wily me]

Search this forum, it was discussed in length already. IMHO the answer is NO! depending on usage schedule.

 

[wily me]

I agree with you.

I also believe that switching it on/off shortens the lifespan of the heating element.

Also the lifespan of the geyser. The cooling heating place stress on the welding joints creating premature failures. Cooling down also creates vacuum and if the vacuum breaker is ineffective the above stresses is even worse.

 

[Zewp]

I also can't imagine that it can be good for the geyser. If left on throughout the day, the element never has to work very hard because it only has to heat the water up if it drops slightly. Now instead the geyser has to heat the water from icy cold every morning.

I highly doubt a geyser can withstand doing that day after day for a very long time.

 

[czc]

From what I hear Eskom wants you to switch it off so that it doesn't try to draw power at the peak times so that they have the capacity. They're not really worried about your bills.

 

[LazyLion]

Eskom can **** my ***** ****!

 

[MickeyD]

Eskom can **** my ***** ****!

... and then die!

 

[StonerStuart]

Geyser elements are cheap and EASY to replace.
Get a geyer wise timer to turn it off.

And how exactly would turning a geyser off shorten its lifespan if that is the MAIN purpose of the thermostat?

Rather get a timer because it sucks forgetting to turn it on and having a cold shower.

 

[shogun]

I agree with you.

I also believe that switching it on/off shortens the lifespan of the heating element.

Well now that's just ridiculous. The thermostat will turn the element on and off many times during the day when the geyser is "on".

@Op... it depends mostly on whether the geyser is well insulated or not. You say it cools down rather fast. In that case it is not well insulated (perhaps look at a geyser blanket), and there will definitely be savings when turning it off. Conservation of energy says this must be so. Also, as the water cools, the rate of cooling slows. When you keep it hot, the large difference in temperature means the heat loss is more rapid, meaning a greater energy use in keeping it that way.

As far as what the difference may be in terms of cost? That you'll only tell by measuring, but I have a feeling that your flatmate may be correct if your geyser is not well insulated.

The overall decider though... is do you really want to live like that? I've done it for a while... and you will end up with cold showers once in a while. If you are going to go that route, at least install a timer.

First prize though would be to forget about the constant switching, and get better insulation around the geyser.

 

[wily me]

Well now that's just ridiculous. The thermostat will turn the element on and off many times during the day when the geyser is "on".

@Op... it depends mostly on whether the geyser is well insulated or not. You say it cools down rather fast. In that case it is not well insulated (perhaps look at a geyser blanket), and there will definitely be savings when turning it off. Conservation of energy says this must be so. Also, as the water cools, the rate of cooling slows. When you keep it hot, the large difference in temperature means the heat loss is more rapid, meaning a greater energy use in keeping it that way.

As far as what the difference may be in terms of cost? That you'll only tell by measuring, but I have a feeling that your flatmate may be correct if your geyser is not well insulated.

The overall decider though... is do you really want to live like that? I've done it for a while... and you will end up with cold showers once in a while. If you are going to go that route, at least install a timer.

First prize though would be to forget about the constant switching, and get better insulation around the geyser.

Geyser elements are cheap and EASY to replace.
Get a geyer wise timer to turn it off.

And how exactly would turning a geyser off shorten its lifespan if that is the MAIN purpose of the thermostat?

Rather get a timer because it sucks forgetting to turn it on and having a cold shower.

There is a huge freaking difference between switching a geyser element off/on and letting it cool down completely. Do some research before yanking chains.

Geyser insulation is a must anyway as as such are recommended by eScum and Kwikot.

 

[Archer]

Search this forum, it was discussed in length already. IMHO the answer is NO! depending on usage schedule.

So is the answer no, or is it dependent on usage schedule?...

 

[MickZA]

The overall decider though... is do you really want to live like that? I've done it for a while... and you will end up with cold showers once in a while. If you are going to go that route, at least install a timer.

First prize though would be to forget about the constant switching, and get better insulation around the geyser.

Agreed, you're saving electricity by rationing the hot water.

If your buddy is prepared to shower/bath after you tell him you're OK with his theory

 

[Cyberdude]

To answer your question: YES
Switching your geyser off does save money, a lot.
...
...
...
Switching it back on is a different story

 

[froot]

The reason that Eskom actually asks you to switch off your geyser is to lessen the load on the grid.
It costs you as the resident a bit more (arguable as to how much), but overall it does more good than it does bad.

I can switch our geyser off at 7pm in the evening and still have hot water in the morning, so we generally do this.... and we don't even have insulation on the geyser.

 

[shogun]

There is a huge freaking difference between switching a geyser element off/on and letting it cool down completely. Do some research before yanking chains.

Interesting take... I wonder how much damage do you incur each time you shower then... essentially flooding the geyser with cold water, as opposed to letting it cool down over hours during the day? Or is there something I'm missing?

Also... Eskom seems to have a few thoughts on this topic as well: http://www.eskom.co.za/content/DSM_0003FactFictGeyRev2~1.pdf

EDIT: Reading my posts again, they seem unusually harsh. I'm not intentionally yanking chains today. Perhaps I should re-word them.. that's too much effort for now though.

 

[Archer]

It costs you as the resident a bit more (arguable as to how much), but overall it does more good than it does bad.

Explain how switching the geyser off will cost you more, ie, uses more energy over the same time period..........

Hint: it doesnt, which is why I'm curious

 

[froot]

Explain how switching the geyser off will cost you more, ie, uses more energy over the same time period..........

Hint: it doesnt, which is why I'm curious

Under normal circumstances your geyser will switch off until it goes below a certain temperature, then switch on and reach the desired temperature, after which it will switch off again. Imagine this looking like a sinusoidal wave (temperature versus time).

If you switch your geyser off and it cools down for 12h-odd, the amount of energy you spend (in electricity) is more than what you would use if you let the thermostat control it. It comes down to simple physics.

 

[Billy]

From the Kwikhot site: http://www.kwikot.co.za/Consumer/Consumer Information.php

Do you save electricity and save financially by switching a geyser 'on' and 'off'?

Geysers manufactured to SABS standards are strictly controlled in terms of their standing heat loss and the insulation requirements are regulated by SANS 151 (SANS - South African National Standards).

The maximum allowable heat loss for a 150lt capacity geyser (most common geyser size) is 2.6kW per 24 hours at a stored water temperature setting at 65 degrees C and no water is drawn off during the 24 hour period. This translates to a temperature loss of between 10 to 12 degrees C over the 24 hour period. A 150lt size geyser will take close on to 3 hours to heat from completely cold water (15 degrees C) to 65 degrees C, which equates to the usage of 8.72kW of electricity with a 3kW element and will cost approximately R3.92, however one must remember that a geyser is seldom heated from completely cold as not all the hot water is drawn off at once.

Let's say the water in a 150lt size geyser has reached the temperature setting of 65 degrees C and the geyser is then switched off for 12 hours and no water is drawn off. This will equate to a approximate saving of 1.3kW @ R0.45c per kW, thus a saving R0.585c per day and if this practice is carried out everyday over a month (30 days), the monthly saving will be 39.0kW or R17.55 per month, not the high savings some may think they would make.

By switching off the geyser over peak electricity demand times (mornings and early evenings), you are assisting Eskom by load shifting, however saving little monetary wise. Switching the geyser 'on' and 'off' will cause no harm to the geyser.

The only real way to reduce electric consumption on a geyser, which will be of financial benefit, is to reduce the amount of water that is heated and drawn off i.e. reduce your hot water consumption, and reduce the temperature setting of the water on the thermostat. Ideal setting is 50 to 55 degrees in summer and 60 to 65 degrees in winter.

Insert current KwH costs as necessary.

 

[wily me]

So is the answer no, or is it dependent on usage schedule?...

Depends on usage schedule and water use. Period. For example if hot water is only used in the evening and the geyser is switched on in the late afternoon and hot water is used as soon as the water reached an acceptable temperature, without cooling it again by adding cold water, and then switched of again afterwards then the switch off argument makes sense. Then you only heat the water you use. Then again a geyser for hot water storage makes no sense as a instant geyser will do just that. Remember energy is only consumed when the hot water needs to be reheated after use or due to losses. This depends on the volume of water used and the quality of geyser insulation. Thus if you consume 1000L hot water at 60" C per month that is the energy needed to heat the water + (plus) any losses. So the only way to cut the losses is only to heat the water you use. With a well insulated geyser that losses are minimal. In my big extended household that system does not work for me as my losses is insignificant to my actual usage of hot water. The other side is true in that because hot water is so readily available more is used like for washing hands during the day.