Does a smart geyser timer save you money?

I see lots of debate as to whether installing a smart geyser timer can save you money. So I tested one out on my geyser at home. The result – a 25.81% saving in heating time.

And I believe there are more savings to come!

The total for the week was as follows:

Before Geyserwise install After Geyserwise Install
430 minutes heating 319 minutes heating

That’s 25.81% less heating time over a week. Given that the trial was in Durban at the height of summer, with day time temperatures in the roof in excess of 50 degrees Celsius at times, the saving in winter will be even bigger.

Same geyser. Same geyser element. Just a change of thermostat that goes with installing the Geyserwise control system.

How does a smart geyser timer save energy?

The energy going into your geyser is for two things –

  • to heat up cold water that comes into your geyser when you draw hot water, and
  • to replace heat loss from the geyser to the environment around it.

The first is the purpose of a geyser. The second is wasteful and what we’re trying to reduce.

The higher the temperature difference between the geyser and the environment around it, the faster that heat loss will occur.

The Geyserwise smart geyser timer control panel – Energy saving at your fingertips.
With a standard geyser thermostat setup, when we draw hot water, the inrush of cool water drops the temperature and the water is heated immediately so that it is ready for the next time you need it – even if you only need that hot water 6 or 12 hours later. This keeps the water temperature high all the time, maximising the temperature differential to the environment, and thus maximising the heat loss.

Installing a smart geyser timer does not change the amount of energy it takes to heat up the water in your geyser – that remains the same. The trick is to reduce the amount of energy that is lost to the environment. A smart geyser saves heating energy (and money) by controlling when the water is heated up.

Instead of heating the water straight away when you draw hot water, setting the timer to just before you expect to need hot water means the water is left cool until you need it heated up. This reduces the temperature gradient between the geyser water and the environment, and heat loss occurs at a slower rate.

By only heating the water just before you need it, heat loss to the environment is kept to a minimum.

By picking the right time to heat the water, you will reduce wasteful heat loss from the geyser. And as my study shows, those savings in heat loss really do add up!

Interested in saving on your geyser heating bill? Contact us today.

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    Still not convinced? Here’s the daily breakdown.

    Detailed results day by day

    Date Total Minutes Heating (no timer) Date Total Minutes Heating (with timer)
    20/01/2018 39 Saturday after midday 17/02/2018 19
    21/01/2018 57 Sunday 18/02/2018 40
    22/01/2018 60 Monday 19/02/2018 67
    23/01/2018 63 Tuesday 20/02/2018 38
    24/01/2018 93 Wednesday 21/02/2018 59
    25/01/2018 39 Thursday 22/02/2018 38
    26/01/2018 59 Friday 23/02/2018 46
    27/01/2018 20 Saturday before midday 24/02/2018 12
    Grand Total 430 Grand Total 319

    That’s a 25.81% reduction of heating time over a week. Probably also worth mentioning that result is actually very conservative.

    On 25th January I  was away and the water draw on the geyser was far less than usual. This reduced heating time in the pre-timer-install week.

    My evening timer was set to switch off at 6.00 p.m. as we normally only bath after 6.00 p.m. On the 19th and 21st February the bath was drawn before 6.00 p.m. and the geyser reheated straight away. The inefficiency of this is plain to see in the results. (I’ve marked the relevant data entries in red for your ease of reference).

    On top of that, with the big drop in ambient temperature in the roof void the savings are bound to be even bigger through the winter.

    The test was carried out on the standard gravity feed geyser in the roof of my house. Using a data logger I tracked the geyser’s electricity usage over the period of a week. The results were loaded into an Excel spread sheet to add up the time spent each day with the geyser element on.

    To save money on your geyser heating bill, contact us today.