Geyser switch-off could backfire

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gregmcc

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http://www.iol.co.za/news/south-africa/gauteng/geyser-switch-off-could-backfire-1.1091855

Quickhot, one of the top suppliers of geysers nationwide, told The Star that turning off your geyser during peak times isn’t a bad idea, but leaving it off overnight can lead to permanent welding damage.

According to the general manager in Quickhot’s service department, Wietz van Lelyveld, the pipes inside the geyser expand when they are filled with hot water, which is usual. But after five hours or longer without electricity, cold water enters the pipe and the metal contracts. This can lead to welding damage over time and leave your roof dripping from a burst geyser.
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I have tried turning the geyser on only at times & keeping it on permanently.

I have found it's more effecient if I keep the geyser on permanently.

What does seem to help is for example doing the dishes while the other person has a shower/bath (there are 2 adults here). One of us prefers night time showers & the other in the morning. Doing the dishes later seems to impact the electrical bill. So from what I can see it seems that the geyser works hard once in the evening as opposed to twice in the evening.
 
interesting ... I had that happen when I went on holiday once, as I thought I would be a good citizen and save electricity and switch off the geyser. Ended up flooding the house because of a burst geyser. At least now I know the reason :)
 
Venomous said:
I have tried turning the geyser on only at times & keeping it on permanently.

I have found it's more efficient if I keep the geyser on permanently.

What does seem to help is for example doing the dishes while the other person has a shower/bath (there are 2 adults here). One of us prefers night time showers & the other in the morning. Doing the dishes later seems to impact the electrical bill. So from what I can see it seems that the geyser works hard once in the evening as opposed to twice in the evening.
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It is a matter of heat loss. Whatever heat you lose when the geyser is off needs to be be regained when it is switched back on. If you keep it on, it only needs to maintain the temperature, or gain it back partially as you use hot water.

Another debunked Eskom myth. I use prepaid electricity so the electricity I use is already paid for. So fsck Eskom.
 
Solar geyser is not using electricity at all. Will monitor and see what happens. (We switched the power at the switchboard to the geyser off).
 
lcbxx said:
It is a matter of heat loss. Whatever heat you lose when the geyser is off needs to be be regained when it is switched back on. If you keep it on, it only needs to maintain the temperature, or gain it back partially as you use hot water.
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True, but the hotter anything is, the quicker it loses heat, so while a geyser is on, it loses heat the fastest and therefore needs to switch on every now and then to maintain the temperature selected
 
Bundu said:
True, but the hotter anything is, the quicker it loses heat, so while a geyser is on, it loses heat the fastest and therefore needs to switch on every now and then to maintain the temperature selected
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A geyser is built for a purpose. More than a third of the size of the geyser is spent on insulation, optimised to keep water at 65-degrees.
 
lcbxx said:
A geyser is built for a purpose. More than a third of the size of the geyser is spent on insulation, optimised to keep water at 65-degrees.
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That's maybe why the best advice is to set the geyser colder than 65, to around 55, where it loses heat slower....
 
You can also buy thermal material (like think pink) and wrap it around you geyser
allot better than turning it off for the night
 
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Bundu said:
That's maybe why the best advice is to set the geyser colder than 65, to around 55, where it loses heat slower....
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this is interesting.
so you're saying that on an absolute scale, the more agitated a particle is, the more inclined it is to release a larger amount of energy than a less agitated particle?
didn't know that.
what's the principle behind this?
 
murraybiscuit said:
this is interesting.
so you're saying that on an absolute scale, the more agitated a particle is, the more inclined it is to release a larger amount of energy than a less agitated particle?
didn't know that.
what's the principle behind this?
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the greater the difference between the temperature of two 'objects', the quicker the temperature of the warmer one will drop - like a cup of boiling hot coffee placed on a table at 20 temperature - within minutes the coffee will cool down from 100 to say 60 and then it takes much longer to cool down to 20, so the 1st 40 drop was much faster than the last 40 drop - can't remember the scientific reason for it, sorry
 
Well just so that you folks know - I damaged my geyser in similar manner - switching off, after morning usage & back on at evenings and Kwikhot refused to honor warranty when geyeser failed. So on one side you're told by Eskom to switch geyser off to save electricity & on other side when you have geyser problem, the supplier refuses to honor warranty!
Lose, lose situation is what we end up with!
 
2old4this said:
Well just so that you folks know - I damaged my geyser in similar manner - switching off, after morning usage & back on at evenings and Kwikhot refused to honor warranty when geyeser failed. So on one side you're told by Eskom to switch geyser off to save electricity & on other side when you have geyser problem, the supplier refuses to honor warranty!
Lose, lose situation is what we end up with!
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that is why I won't. I asked & got told that. Then ran my ''tests'' in summer. Don't see a benefit in turning it off.

Geysers are designed to stay on. So I only turn it off if i go away for more than 2 days.

Rather cover the geyser to keep it warm.
 
Bundu said:
the greater the difference between the temperature of two 'objects', the quicker the temperature of the warmer one will drop - like a cup of boiling hot coffee placed on a table at 20 temperature - within minutes the coffee will cool down from 100 to say 60 and then it takes much longer to cool down to 20, so the 1st 40 drop was much faster than the last 40 drop - can't remember the scientific reason for it, sorry
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See: Fourier's law and Newton's law
 
When setting the geyser temperature be aware of Legionnaires' disease.

70 to 80 °C (158 to 176 °F): Disinfection range
At 66 °C (151 °F): Legionellae die within 2 minutes
At 60 °C (140 °F): They die within 32 minutes
At 55 °C (131 °F): They die within 5 to 6 hours
Above 50 °C (122 °F): They can survive but do not multiply
35 to 46 °C (95 to 115 °F): Ideal growth range
20 to 50 °C (68 to 122 °F): Growth range
Below 20 °C (68 °F): They can survive but are dormant

http://en.wikipedia.org/wiki/Legionellosis
 
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