Geyser Blankets and electricity savings

[pouroverguy]

Hello Friends

So got my bill for April and my electricity usage was insane (for one person living in a small place). I checked yesterday, and my geyser used around 6 units in just a few minutes over an hour. It seems just having my geyser on for an hour a day is going to add a significant cost to my bill in these winter months here in Cape Town. The geyser is on the roof and it's really cold now, so I can imagine it will be losing heat relatively quickly as well which isn't ideal.

Wanted to ask what your thoughts all are on Geyser blankets - do they really make a difference, do you have any brands to recommend if so etc? Found a company called Aerolite that says this: "The Aerolite has an R-value of 3.38, almost Four times more efficient than commercially bought Geyser Insulation Blanket." I've seen a cheap R199 blanket with an R-value of 1, so interested to hear if there is that much difference between the R-values as well.

Thanks in advance

Edit: now I've found a website that's saying switching it on and off does NOT save electricity, so I'm quite confused. https://www.isotherm.co.za/switching-off-geyser-really-save-energy/

 

["D"]

How much for the Aerolite?

 

[BadBoyGP]

I put one, definitely helps.

I heat the geysers at aroud 12-14h00 and they stay hot.

Leroy has them for 250 with pipe warmers as well

 

[OhYeah84]

I put 2 blankets on our geyser which is located inside the roof. Geyser burst (small little hole), water dripped onto the blanket and then into the ceiling causing a huge discolouration and wet patch that needed a replacement.
Other than that, I never saw anything really convincing that it worked. For an outside geyser though, the standard blanket bought at Builders Warehouse isn't likely to work as it will be exposed to the elements and deteriorate quickly.

PS: I haven't put those blankets back on as I never really saw much of an electricity saving.

 

[pouroverguy]

How much for the Aerolite?

website says "average price for Geyser Blanket installed is between R 750 and 950, depending on the size."

Geyser Insulation – Aerolite Installers

aeroliteinstallers.co.za

 

[Operator]

A geyser blanket on the roof (outside) is not going to stand up to the weather. You are going to be wasting your money. Secondly a geyser is already insulated inside and a geyser blanket will not add much extra insulation.

 

[Mike Hoxbig]

Edit: now I've found a website that's saying switching it on and off does NOT save electricity, so I'm quite confused. https://www.isotherm.co.za/switching-off-geyser-really-save-energy/

You can't generalise, it depends on usage habits.

Every time you open anything but cold water, it will drain the geyser, replacing it with cold water and triggering the geyser to turn on.

A timer makes a difference when you know which hours you definitely need hot water. If you need hot water all the time then you're screwed either way...

 

[pouroverguy]

You can't generalise, it depends on usage habits.

Every time you open anything but cold water, it will drain the geyser, replacing it with cold water and triggering the geyser to turn on.

A timer makes a difference when you know which hours you definitely need hot water. If you need hot water all the time then you're screwed either way...

What is the difference between a timer and just switching on the geyser for an hour at a certain time during the day? Will one use more electricity than the other (Sorry I know is probably a dumb question).

 

[WAslayer]

Why is your geyser on the roof..?

Geysers are already well insulated, as they have a maximum allowed heat loss of something like 1.5 Deg C over some time span when the element is not on, I forget the exact figures, but its low enough that switching the geyser on and off results in negligible if any savings.. those who do claim to save doing this, possibly have geysers not up to standard in terms of the maximum allowable heat loss..

 

[AlphaJohn]

Also helps to lower the thermostat.

Dropped mine a while back, its amazing how much you save on a couple of degrees.

 

[pouroverguy]

Why is your geyser on the roof..?

Geysers are already well insulated, as they have a maximum allowed heat loss of something like 1.5 Deg C over some time span when the element is not on, I forget the exact figures, but its low enough that switching the geyser on and off results in negligible if any savings.. those who do claim to save doing this, possibly have geysers not up to standard in terms of the maximum allowable heat loss..

My bathroom is really small, so when the landlord had it redone I requested it be placed on the roof instead of inside the bathroom visible as it was before. Made a massive difference in terms of space. Interesting - so perhaps having a timer installed may make more of a difference than a geyser blanket? Will experiment and leave the geyser on for 24h and compare the units used to leaving it on for an hour a day.

 

[pouroverguy]

Also helps to lower the thermostat.

Dropped mine a while back, its amazing how much you save on a couple of degrees.

What do you have yours set to in the winter? Mine is at 55 and I've thought about going lower.

 

[Mike Hoxbig]

What is the difference between a timer and just switching on the geyser for an hour at a certain time during the day? Will one use more electricity than the other (Sorry I know is probably a dumb question).

No difference, just easier to manage. You don't have to worry about forgetting to switch it on/off and either wasting power or not having hot water...

 

[STORMERSFAN]

What is the difference between a timer and just switching on the geyser for an hour at a certain time during the day? Will one use more electricity than the other (Sorry I know is probably a dumb question).

Eskom does that for you free of charge lol

 

[AlphaJohn]

What do you have yours set to in the winter? Mine is at 55 and I've thought about going lower.

Did not take note of the actual temp, just know I lowered it. Basically when I shower now I just have add a touch of cold water for right temp.

Also when I shower I practise camping rules,
wet then turn off
lather,
turn on for rinse.

 

[pouroverguy]

Eskom does that for you free of charge lol

I think I've only been load shed once or twice in the past couple of weeks. Cape Town rocks.

 

[noxibox]

Taking hot water out and replacing it with cold water should not immediately result in the element turning on. There should be some minimum temperature below the set temperature that triggers it. This would typically be several degrees meaning a fair amount of hot water must be used.

Your cylinder shouldn't lose more than 10 degrees in 24 hours if left unused.

Geyser blankets don't do anything noticeable if your cylinder isn't leaking a lot of heat. I've done overnight tests leaving it off in the middle of winter and there was no difference in the temperature the next morning.

 

[Zuner]

I use a smart timer, one that tells you the usage in KW/H, to the people saying it makes no difference you are wrong.
In my previous place the geyser was in the ceiling, no blanket. I lived alone.
I tested geyser on all the time, and geyser on for x amount of time in the morning before I shower. Current x=50min.

The geyser stays off until the next morning, on weekend i have a longer timer to make sure the geyser gets properly hot for some time to make sure no bacteria growth happens.

This resulted in savings, permanently on was 4+ kw/h per day, sometimes spiking to 6.
Timer is below 2.3kw/h per day and a spike of 6 for one day on the weekend.

The key here is living alone so crazy hot water is not needed until the next morning, and having the geyser off before you shower, heating water after you have showered is just a waste, higher geyser temp = more thermal loss to environment over the course of the day and night.

 

[BadBoyGP]

I use a smart timer, one that tells you the usage in KW/H, to the people saying it makes no difference you are wrong.
In my previous place the geyser was in the ceiling, no blanket. I lived alone.
I tested geyser on all the time, and geyser on for x amount of time in the morning before I shower. Current x=50min.

The geyser stays off until the next morning, on weekend i have a longer timer to make sure the geyser gets properly hot for some time to make sure no bacteria growth happens.

This resulted in savings, permanently on was 4+ kw/h per day, sometimes spiking to 6.
Timer is below 2.3kw/h per day and a spike of 6 for one day on the weekend.

The key here is living alone so crazy hot water is not needed until the next morning, and having the geyser off before you shower, heating water after you have showered is just a waste, higher geyser temp = more thermal loss to environment over the course of the day and night.

I am with you.

I have measured about a 15-20% saving in power if always on.

Less then 5°C drop in temp over 12 hours compared to 10°C without blanket over the same period.

 

[richjdavies]

TLDR; because your geyser is outside, treat it like a kettle. Heat it, use it, then switch it off... Else you will be wasting huge amounts of energy.

Geysers are already well insulated, as they have a maximum allowed heat loss of something like 1.5 Deg C over some time span when the element is not on, I forget the exact figures, but its low enough that switching the geyser on and off results in negligible if any savings.. those who do claim to save doing this, possibly have geysers not up to standard in terms of the maximum allowable heat loss..

^^
There are tests. Yes. Those tests are done on a brand new geyser in a room at room temperature (20degC) with no wind and dry and no overflow pipes etc, and no usage. A class B 150L geyser will lose 1.1kWh per day like that. I.e. if not switched on it will lose around 5 degrees per day. Which if you want it back to 60 then you'll use that power back up again. So a timer saves pretty much nothing in a lab condition.

From: http://blog.homebug.co.za/?p=34


BUT...
1. We aren't talking about lab conditions here we are talking about a wind and rain exposed geyser. That will lose MUCH more heat. Does blowing on your food make it colder... Then same here. You need to shelter and cover your geyser. The insulation is not sufficient for outside. A wet geyser will also lose much much more.
2. The lab test doesn't USE any water. So doesn't account for usage as colder temperatures. Your geyser should mainly be using energy to heat usable water not just sit there. Back of the envelope it's 1kWh for every 20L used (at 60C heating from 20C). But if it's cooler it uses less... Half that temp rise -- i.e. using water at 40 rather than 60 uses half the energy.

Ultimate answer... It's physically impossible to use MORE power by switching it on and off... So why not try!
It will only save you a little if your geyser is inside and you switch it off when you aren't using it and it's at near full temperatures

When you save substantially is when:
1. It can be off for long period of time -- e.g. you are away, not using that bathroom etc. About 1-2kWh per day saved.
2. You use colder water -- e.g. for cleaning the house, washing hands, dishes etc and running the the tap until it's warm. If you use 100L at 60 degrees that's about 5kWh of energy. Use it at 40 degrees and that's more like 2.5kWh!
3. The geyser is leaking, faulty or just old. A dripping hot pipe or overflow will use oodles of power, so either fix or at least whilst waiting for the fix switch it off whenever you can.