Does switching your geyser off save electricity - A simple experiment

[bekdik]

AIM:

To simulate the action of an electric geyser by measuring the amount of electricity required to heat/reheat various amounts of water​

APPARATUS:

• An electric kettle
• A kitchen cup
• A watch - preferably stopwatch

METHOD:

• 1st Pass

1. Empty kettle
2. Fill cup from cold tap
3. Empty cup into kettle
4. Repeat until kettle is full, while keeping count of number of cups
5. Plug kettle into electricity supply
6. Switch kettle on and measure the time taken to come to the boil
7. Calculate electricity usage as <number of minutes to come to boil>/<Number of cold cups of water> and note the result together with time and cup count

• 2nd Pass

1. Fill cup from the kettle and discard
2. Cool cup in cold water
3. Fill cup with cold water and pour into kettle
4. Switch kettle on and measure the time taken to come to the boil
5. Calculate electricity usage as <number of minutes to come to boil>/<Number of cold cups of water> and note the result together with time and cup count

• 3rd and subsequent Passes

1. Fill 2 cups from the kettle and discard
2. Cool cup in cold water
3. Fill cup with cold water and refill kettle with the number of cups removed there from
4. Switch kettle on and measure the time taken to come to the boil
5. Calculate electricity usage as <number of minutes to come to boil>/<Number of cold cups of water> and note the result together with time and cup count

• Repeat using 1 extra cup of hot water for each pass until kettle is emptied
• Plot a graph -
  Horizontal axis = ascending number of cups of Cold Water
  Vertical axis = Ascending time taken for kettle to boil​

POST RESULTS
POST CONCLUSION
​

 

[alanB]

Hi

We've just posted our latest geyser test. We simulated a geyser time switch to try and understand how that would help.

http://www.powersaving.co.za/index.php?q=con,65, misc

 

[Moederloos]

alanB: This matches my own observations.
For a long time, I switched the geyser off every day (and by a long time, I mean over a year).
Then, one fine day, I decided not to (various reasons).
Since then (and this has now been at least one year), I have noticed no saving / increase whatsoever on my power usage.

While my observations are not scientific (and I do not intend them to be taken as such), they do however show me that switching a geyser off does not affect power consumption in any way, OTHER than to shift load from peak to off-peak.

 

[mancombseepgood]

Hey Bekdik... you'd save alot of energy (not to mention time) if you got a geyser bigger than your kettle!

 

[stoke]

So I can almost sue governmint for installing their mandatory regulator switches in my house, and then penalising me for using more electricity because of their mandatory switches.
Loverly!
Please please please come to a scientific conclusion on this issue.

 

[bekdik]

Hey Bekdik... you'd save alot of energy (not to mention time) if you got a geyser bigger than your kettle!

 

[Moederloos]

So I can almost sue governmint for installing their mandatory regulator switches in my house, and then penalising me for using more electricity because of their mandatory switches.
Loverly!
Please please please come to a scientific conclusion on this issue.

Well, the switches DO do what they are meant to do - shift load during peak times. That is their purpose, and it does work.
However - they do NOT save you power, nor does switching the geyser off.

 

[stoke]

Well, then peanalising us for using power when "they" have a direct effect on our power usage is blatantly criminal?

 

[bekdik]

Hi

We've just posted our latest geyser test. We simulated a geyser time switch to try and understand how that would help.

http://www.powersaving.co.za/index.php?q=con,65, misc

Interesting.

Was the geyser insulated? I suspect that a well insulated geyser would have fewer reheats.

 

[mancombseepgood]

Our monkeypality bypassed my switch when it packed up... they were going to send someone to install the new model... over 6 months ago...
I won't phone them to remind them now... thanks for the info guys!

 

[Moederloos]

Well, then peanalising us for using power when "they" have a direct effect on our power usage is blatantly criminal?

Well, the jury is out on the effects it has on usage - but it certainly is not a magic bullet to save vast amounts of power.

 

[The_Unbeliever]

I think there'll be a couple of scientific tests on this one as well...

Somebody'll no doubt design a geyser with built-in agitator to keep the water in movement until everything's constantly heated.

 

[Moederloos]

If ripple relays actually worked (as in - saved power overall) and Eskom was truly committed to fixing this problem, simply installing one in each house / office would solve the power problems.

The truth is - geysers do not really consume that much power (relative to total output by Eskom), and the switches are not that effective at saving power.

 

[bekdik]

I think there'll be a couple of scientific tests on this one as well...

Somebody'll no doubt design a geyser with built-in agitator to keep the water in movement until everything's constantly heated.

And that would use even more power!

 

[Moederloos]

And that would use even more power!

Ok - since we are debating...

Will it (use more power). If it is connected to the thermostat "switch", the "agitator" may use 100W (I am thinking a small, low RPM, "blade").
Since the element is 3Kw, the "agitator" could save 2.9Kw for every hour it cuts off the heating cycle.

 

[mancombseepgood]

Assuming that the element is heating the water unnecessarily, yes.

 

[flarkit]

We've had a timer on our geyser for 6 weeks, turning it on at 21h00 and off at 06h00. It hasn't seemed to save us significant amounts. I will be adding a geyser blanket this month as well, in the hopes that the geyser won't lose as much of it's temperature in the 15 hours that it's turned off. I'm also thinking of changing the "off" time to 07h00, to reduce the period that the geyser cools down.

Surely there has to be some balance where, having the geyser off for a period, does reduce the amount of electricity required to keep the temperature above 50-degC?

Hmmm... more thinking: if we increase the time which the geyser is turned on, won't we be increasing the number of times where it reheats? It seems that the best bet is to have the geyser off for as long as possible, whilst minimising the amount of heat which the water loses.

 

[Moederloos]

Surely there has to be some balance where, having the geyser off for a period, does reduce the amount of electricity required to keep the temperature above 50-degC?

Maybe - the question is "how much of a difference?"

Saving 20W is not worth the schlepp.

 

[mancombseepgood]

Prepaid

We have noticed our prepaid 'usage' going up steadily... even now over load shedding, we are up 100kwh on last month. I am getting suspicious and want to install my own useage meter - one of those inline ones that fit in the DB with the circuit breakers.

I had a friend who moved into a house (rented it) and suspected there was a problem with their prepaid meter as their electricity was being used up so quickly. It turned out the municipality had theirs on an incorrect setting resulting in them paying more per kwh... the municipality corrected it and 'backpaid' them for the whole prior year (when the previous tennant was there)... so now they have a years free electricity thanks to their previous tennant... poor guy...

 

[LCBXX]

We have noticed our prepaid 'usage' going up steadily... even now over load shedding, we are up 100kwh on last month. I am getting suspicious and want to install my own useage meter - one of those inline ones that fit in the DB with the circuit breakers.

I had a friend who moved into a house (rented it) and suspected there was a problem with their prepaid meter as their electricity was being used up so quickly. It turned out the municipality had theirs on an incorrect setting resulting in them paying more per kwh... the municipality corrected it and 'backpaid' them for the whole prior year (when the previous tennant was there)... so now they have a years free electricity thanks to their previous tennant... poor guy...

Same here. Our usage has actually gone up after this 4-hour loadshedding started. I was expecting to have to buy less electricity but no.

BTW, did the municipality adjust your mate's pre-paid box via PLC or did they physically do a site visit to adjust the thing?