Hot water energy saving

A list and short description of electric hot water energy saving timer 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.

Freedom Power Saver

Professionally installed digital timer. Battery backed. 10 year part and labour warranty. Advertises savings "up to 30% or more each and every month"

Green Squirrel Power Saver

Breaker box mounted digital timer. Advertises most customers achieve a saving of 30% or more every month. Installation by registered electrician. Device and installation are guaranteed for five years.

Green Squirrel
TradeMe (member site)

Greentech Electric Hotwater Saver

Breaker box mounted digital timer with remote control for manual operation and time setting.

The GreenTech website says: "Savings made depend on your usage but is usually 20-30% of your hot water costs. Payback from saved power is usually 6 months"


Senztek EcoStat Controller

The Senztek EcoStat Controller achieves hot water energy savings using three methods simultaneously:
    • Controlling the amount of hot water stored
    • Setting target temperature bands for different periods during the day
    • Temperature automatically increased to 60 centigrade once every 72 hours to meet health standards for safe hot water storage
The device provides custom maximum temperature and minimum temperature settings for three time periods. Energy use is lowered when the hot water system is not being used and the user can take advantage of night rate electricity if available. In addition temperature is automatically increased periodically to meet health standards for safe hot water storage.Installed surface mount tank sensors monitor hot water cylinder status and feed this information back to the intelligent controller device to achieve these outcomes.

Senztek state: "The EcoStat™ should save between 10% and 20% of your hot water heating costs, depending on how much water you use."

Senztek advise that a qualified tradesperson can install and configure the device in one to two hours.An EcoStat user manual is available from the Senztek downloads page. A separate installation and setup manual is available to qualified installers on request.

The Senztek EcoStat product is similar in operation to the Senztek SolaStat product - The SolaStat product is specifically designed for solar hot water systems.

Retailers & distributors:

See Senztek's distributors page.


Any qualified tradesperson. Also check the distributors link above for experienced installers.


The Power Panda (Hot water)

The Power Panda FAQ advertises savings of 
20-30% on every power bill.The Power Panda can be installed by any registered electrician. Power Panda estimate an electrician will require 15 minutes to complete an installation.Power Panda provide a 5 year warranty for the unit. Payment plans are available.The Power Panda FAQ now includes a link to a special offer registration page.

Power Panda has been advertised on NewsTalk ZB radio.
A Power Panda News blog provides information about power companies, electricity charges, and energy saving. 
In October 2010 Power Panda advertised for experienced sales people and indicated door-to-door campaigns are strongly preferred.

The outward appearance of the Power Panda device is similar to that of a
fairly standard breaker-box mounted digital timer like the DHC15 timer at the bottom of this page. DHC15 type timers can be obtained at most electrical wholesalers or through your local electrician.

Power Panda also markets Total Saver Residential. This product is covered on the energy saving devices page.


Please check the Power Panda site for the latest information on this device. Power Panda are a relatively new company and have changed aspects of the product marketing over time including details of the guarantee. An archive of changes made to the Power Panda item on this page is maintained here.

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

Shower Timers

This site does not track shower timers in detail, but here are a few examples: Water Pebble (GreenTech), Efergy Shower Timer (NZNature).


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.

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