Hot water energy saving

A list and short description of electric hot water energy saving control devices available in New Zealand.

This site also lists appliance energy monitorsstandby power eliminators, and home energy monitors available in NZ.

Household hot water use averages 27% to 40% of total household energy use in New Zealand depending on which statistics you rely on. Individual household use is sometimes more. Saving energy in this area can make a big difference to the power bill. Hot water system energy saving devices offer a range of methods to reduce energy use.

Smart Power Controller

Smart Power Controller by Senztek. Enables more control over hotwater energy usage. Optional in home displays available as extras. Full installation service including cylinder and solar panels if required.

Smart Hotwater (startup package)

Breaker box mounted digital timers

Breaker box mounted digital timers are available from most electrical wholesalers in New Zealand. The following are only a small selection from electrical wholesalers who advertise this product online.

Most are rated at 16A* for resistive loads like hot water cylinders and all must be installed by a registered electrician. Some have battery backup to retain the time and settings if there is an interruption in mains supply.

Warranty will be different for each device. Each may support different numbers of on/off settings and time periods.

Links direct to product:


Or, ask your electrician.

*approximately 3800 Watts.

Non-electrical control methods and devices


Discussion area for hot water energy saving devices. 

 16/10/2010 10:48  Max Patmoy - Napier A lot of the website is down as of 16 October 2011. I would be vary weary of buying this
 16/10/2010 11:37  Ema-1 [Moderator] John Whyte from Power Panda posted to the Talk page here a couple of days ago. My best guess is that PP are in the process of revising marketing material at present.
 23/10/2010 16:06  Peter Cox I'm a retired electrician with electronics and computer qualifications,and have waited for many many years for what seems to me a logical answer,technically,to hot water heating.

And that is,like many applications in modern industry,the variable voltage variable current applications.........for example,in resistive loads,stage lighting........and so too with 2 and 3kw HW cylinders where time and temperature are the controlling factors.
In other words ramping up and down of a volt/current supply to a heating element.
The only "fine tuning" needed to be adjusted is the differential of on/off conditions as in a thermostat....which is normally anywhere from 4 degrees C to about 10 degrees C.

These days such supply waveform "cutting" either horizontally or vertically is not a problem,and neither is current control with todays technology in heat efficiencies and heat disappation.
They do it with everything else it seems EXCEPT hot water heating.
Always wanted to know "why not?"
Maybe one day..............
 12/06/2011 21:12 MattHi there, these energy saving devices appear to make substantial claims about saving power. I am surprised that they are not more popular and more talked about. If the claims are true then I would be interested in getting one. Does anyone have any feedback on their experiences with any of these devices. Thanks.
 01/06/2012 06:15 JeffA Gas Water Heater Timer is another great way to save enrgy and extend the life of your water heater. See it on the web.
 27/03/2013 07:52 BobWe've had the Senztek Ecostat installed for about a year in our bach and it works very well. For the two of us we set it to use the top sensor and have no problem with the quantity of hot water available. With guests it's simple to change to use the lower one and have the full cylinder 

It's a little fiddly to set but we've gotten used to it. Certainly our power consumption has gone down substantially but it would be hard to be specific by exactly how much
 21/01/2014 10:48 StuartPower Panda devices were advertised on GrabOne and other sites. I convinced the sites to not promote these because they have no scientific proof of significant savings - only testimonials that are short on specifics. The other thing to keep in mind is that if the AVERAGE temp of water cylinders is below 60 degrees, legionella can develop - see
So timer and dual sensor devices which lower your cylinder temp could expose you to a little more risk
 21/01/2014 13:19 Ema-1 [Moderator]Hi Stuart. In your first paragraph about your discussion with GrabOne I'm pretty sure you are talking about the claims made by Power Panda for Power Panda's power factor correction devices.

The hot water timers on this page are a different product by the same company.

Regarding legionella. That's an interesting question about DBH compliance for hot water timer products. I don't know the answer to that one. DBH NZ recently released an updated compliance document and conformance to NZ standard (in a different document) is also important.
 26/04/2014 18:25 WilloughbyHi! A whole bunch of links on this page don't work anymore...
 26/04/2014 22:28 Ema-1 [Moderator]Thanks for pointing that out! I'll sort in day or so.
  Ema-1 [Moderator] Updated to remove outdated products.
 16/06/2014 11:28 TracyHello, I've just stumbled across this page in the search of some advice around a shower timer for our home. We have 3 teenagers who take pleasure, much to my frustration, in VERY long showers. We've tried silly stick-on timers but the onus is on them to turn the shower off when it signals. I'm wanting to have a device installed that will allow them 7 minutes of hot water and then it turns itself off! Is that what the Unipro and Vista devices do? Can you point me in the right direction please? Many thanks
 17/06/2014 13:09  Ema-1 [Moderator]Thanks for your question. Those devices will not suit your purpose. Take a look at something like this - - the purchase page lists an NZ distributor.

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