Beware of turning your geyser off

01 Jul 2011

While electricity provider Eskom has encouraged people to switch off their electric geysers overnight in order to save electricity, plumbers warn that leaving them off could damage the hot water pipes and even cause the geyser to burst.

Turning off a geyser at night to save electricity could result in burst water pipes and damage to the welding in these pipes say plumbing groups.

Kwikhot’s general manager of the service department, Wietz van Lelyveld, warns that the pipes inside the geyser expand when they are filled with hot water but after five hours or longer without electricity, cold water enters the pipe and the metal contracts.

This, he says, can lead to welding damage over time and may result in a geyser bursting.

Ryan Moore, managing director of Roto Rooter, says that while a geyser can be switched off during the peak demand period, it should be switched on before 10h00 to prevent damage to the geyser.

He says that Eskom used to insist that geysers were fitted with ripple relays so that these could be remotely controlled during peak demand but the utility had phased these out about ten years ago.

Mooreconfirmed that the company installs more replacement geysers over the winter period when customers are told to save energy by turning off their geysers without realising that they can be causing other damage.

Van Lelyveld and Moore both say that the best way of saving money on electricity is to install a solar water heater and, while the initial investment is relatively high, the savings are significant and the maintenance costs are minimal.

Readers' Comments Have a comment about this article? Email us now.

The article has left a big question mark in my mind.
Firstly the ripple relays have not been phased out 10 years ago as they are still in operation in some areas in Johannesburg.
Secondly, I am switching my geyser off for the last about 8 years and there is no problem with my geyser.
With regards to the pipes inside the geyser, maybe Kwikot can be more specific on what type of geyser they are talking about. If welding is of such a poor standard that a change in temperature of about 35 degrees (from ±15 to 50 degrees) with the maximum at about 50 - 55 degrees, (mine is at ± 45 degrees), then I seriously question the quality of Kwikot’s geysers.
I have heard from one plumber that the average lifespan of today’s geysers are about three years - that is his experience with his regular clients. He also indicated that some of the long warranties which one had on some geysers, have all fallen away. This is appalling. Maybe someone need to do some tests on our modern day geysers and expose the poor quality we are getting. - W. Ries

Cold water also enters the geyser everyday when you use it to shower or bath, how is that different from the cold water entering the geyser when you switch it of?
I will appreciate any explanation on the difference. - Anon

It happened to me 2 weeks ago. - S. Brierley

What is the deference between running a full bath (cooling the geyser down all the way) and leaving the geyser off during the night?
If you have a copper geyser (like I have) this does not even play a roll. I deal with solar systems every day, and if they are not properly installed you are worse of as if you did not have one at all.
Kwikhot should rather educate the public about replacing the anode in the geysers. (an anode prevents the geyser from being “eaten” from the inside by the water.
Replacing the anode after about 18 months will allow your geyser to last even up to 15 years and not just 3 years. - David Hartzenberg

If the geyser cools down in 5 hours, you have a crap geyser.
Cold water always enter the pipes that is why you fit a geyser.
This means that you should not bath as the volume of water leaving your geyser would be replaced with cold water and this will cause your geyser to burst.
The problem comes that over the years the geyser companies has changed from copper to iron tanks. Copper is softer, more flexible and less susceptible to corrosion. The iron tanks has anode that needs to be replaced regularly to reduce corrosion. This is not done and the tank seams are first to corrode due to the heat when welding. To proof my point, why does hot water copper pipes from the geyser to the tap not burst all the time. My pipes run outside the house, cools down and heats up every time you use hot water. Same pipes for over 36 years.
O and by the way Solar geysers only heats the water when the sun shines, thus the geyser is switched off for more than 10 hours in the day. The solar geysers element is set to work at night when the sun does not shine. So why would this not happen to solar geysers. Yes it is the same geyser with just extra pipes, unless you get the fibreglass tank version. - C. Viljoen

I also used to switch of my geyser then I my brother advised me to buy a time switch it switch itself on 3:00 morning then off again by 6:00. Am I also in danger of geyser burst? How could Eskom advice us for something which will cost us more than the electricity itself. - Mamothe

I think the article is poorly researched and lacks sufficient information to make an informed choice.
There are a few proven dangers to switching off the geyser, but they deal with extremely cold climates where water freezes in pipes and other similar related issues.
Expansion & contraction takes place during normal usage as the hot water leaves the geyser and is replaced with cold water, in winter, this temperature difference is greater than in summer and can obviously add to metal fatigue- especially on steel geyser tanks where the effects are greater than with copper geyser tanks.
There is always more wear & tear on a geyser and its components in colder weather where the cold water is at a lower temperature than during other times of the year. The element and thermostat activate more frequently and have to work longer to heat the water & to keep it hot. The expansion and contraction on the components is also greater due to the difference between the lower base temperature and the hot water temperature. This does not necessarily mean that geysers burst more in winter or if switched off for 12-18hrs a day, as normal usage will cause expansion/contraction anyway.
Regarding the claim that maintenance costs on a solar geyser is minimal; solar geysers have all the same components of a normal pressurised geyser installation. Pressure valves, vacuum breakers, tp safety valves are on both types of systems and therefore have the same maintenance costs and lifespan. The backup element and thermostat on a solar installation obviously has to heat less and therefore will have less maintenance over time.
Better advice for your readers is to advise them to insulate the water pipes and to install an electrical time switch on the DB Board. While an installation of a solar geyser will save the most electricity, it is also the largest expense. It is disingenuous to tell readers that "maintenance costs are minimal" on a solar geyser installation.
Please research your articles more thoroughly in future. - Harold Josman

I find it very disconcerting that information like this is passed off as factual, when even the smallest amount of logical thought applied to the situation will rubbish the assertion that switching off your geyser is bad for the geyser.
Geyser bursts occur when:
1. The temperature or pressure in the geyser exceeds the design specifications of the geyser by a large margin ( unlikely as the TP valve opens if the pressure exceeds the rated pressure of the geyser and the temperature exceeds 94 deg C). This would normally happen if the thermostat failed and the geyser would heat up to boiling point.
2. The geyser pressure vessel is compromised due to a lack of maintenance. Mild steel geysers come fitted with a sacrificial anode that has to be replaced  regularly so as to inhibit corrosion, when this is not done, the hot water will accelerate the rate of corrosion especially in the areas around the element and the hot water outlet. In short it has a hole rusted through it.
3. A vacuum is formed in the geyser and the vacuum breakers fail. (this is a vacuum collapse and not a burst)
The rate at which the whole thing expands and contracts is a great deal slower than would be required to cause metal fatigue as heating typically takes an hour or more, thereby giving the metal sufficient time to expand. Pipes bursting would be either wear and tear or badly fitted pipes as especially copper pipes are extremely responsive to temperature changes and they routinely are subjected to massive temperature fluctuations. The fact that geysers often fail in winter is because the whole system takes more abuse during winter and to my mind is a natural consequence of this.
The major causes for geyser failures are too high temperatures, corrosion due to lack of maintenance and the use of cheap materials to make geysers as opposed to using more corrosion resistant materials like stainless steel, copper and glass fibre options and pray tell how will having a solar geyser change the situation.
All in all badly researched and deeply flawed arguments that presents anecdotal evidence as facts. - Gerwyn Wilsnagh

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