By David Senn
Matrix Engineering proprietor, David Senn,
is the developer and manufacturer of the
Econergy® super efficient domestic heat pump water heater, recently ranked by Consumer as the most efficient electric water heater in its May 2009 test.
A trip to your hot water cupboard (and there is an 82 per cent chance you've got one) usually reveals an old insulated tank of hot water with an oversize jug element in the bottom of it. You guessed it, the same technology that was developed back in the 1920s which adds up to a horribly inefficient use for high grade energy. In the average home it sucks an enormous 3,300kWh of electricity per year to keep you in hot showers (or 38 per cent of the total bill).
Like many readers, I studied thermodynamics in my tertiary training and hence was well indoctrinated in the orthodoxy of good thermodynamic engineering, compliments of Professor Raine, School of Mechanical Engineering.
In 2004 I was renovating my two bedroom flat in Grafton, Auckland that had a delightful pre-historic 30 gallon hot water cylinder specimen dating to the 1950s. I was determined and resolute that I would biff it out and replace it with the right, modern, and thermodynamically correct solution and proudly told my friends that I was going to do things ‘properly'. However, when the time came to make the decision, I was forced to put a replacement unit - essentially the same thing - back in again.
Gas water heating was not possible due to the lack of gas mains on the site, and solar water heating would have been unsightly and difficult to get past the body corporate (the N.I.M.B.Y conundrum). There were, of course, no heat pump water heaters suitable for retrofitting into a two bedroom property back in 2004. I was chagrined by the experience and it got me thinking.
About the same time I found out about the Mahana heat pump, a neat invention that could heat water to 85 degrees Celsius for use in dairy sheds. I figured, “if it is possible to heat water to 85 degrees Celsius for use in dairy sheds using a single stage heat pump, it must be possible to heat it to 60 degrees Celsius” for use in domestic hot water applications.
Thus, the seed of an idea was formed. After developing a concept in August 2005, I got started on building a prototype water heater using a super-efficient heat pump cycle in the weekends, as you do. The prototype delivered a basic COP of about 2.5, or 2.5 times the energy out compared with the energy in. Not enough to get really excited about, but it impressed me enough to convince my better half to leave the comfortable consulting job at Beca and get started on developing the real thing. I was kindly offered a small corner of my colleague, Allan McCreadie's (Armadillo Engineering) workshop, in Ardmore.
I had done some basic engineering R&D before in appropriate technology and wind energy sectors, which was invaluable help in getting started. There were a few trials and tribulations in the process, although many serendipitous events also. The first electronics company unfortunately didn't produce a working prototype. The first two prototype units were mounted in ceiling cavities, developed leaks, and my trial customers ended up putting water buckets under the ceiling to catch the drips - not to mention one of my helpers putting his foot through a friend's ceiling.
Finally we found the right electronics company, got R&D funding from tech NZ with help from Alta Vos from Enterprising Manukau, broke through and had the first ‘production' - I use that term loosely - units installed in late 2007.
We also cracked the efficiency constraints. The first production units were seriously efficient. If fact, we were able to make calibrated tests demonstrating an ‘all in' COP of 3.5 at typical Auckland conditions (60C hot water/15C water/15 C air) temperature.
We obtained a patent to protect the technology and started selling in 2008, and at that point we quickly realised that the playing field was stacked against us. If you installed a solar water heater you were eligible for a grant from the government. So we were $1000 down when selling against a solar water heating system with no support for our water heaters. This, of course, is all stuff you never think about when doing your feasibility study and, in fact, it is impossible to consider all possible future events. So we lobbied the government. We have recently submitted a proposal to the Energy Minister, Hon. Gerry Brownlee, for consideration. I wish to thank all who have supported this proposal, especially John Walley of the MEA.
We have now sold and installed close to a couple of hundred of our systems, from Mosgiel to Kerikeri. Perhaps the biggest break we have got to date was that our HP4000LT product was selected for the Consumer heat pump water heater test published in May 2009. The Econergy® HP4000LT heat pump water heater beat all of its competitors in the test.
The Consumer test report is available free to the public at: http://www.consumer.org.nz/reports/heat-pump-water-heaters.
According to Bill Whitely of Consumer magazine: “The Econergy HP4000LT was the star of our heat-pump water heater test, blitzing its competitors. These water heaters work by using warmth from outside air to heat your hot water. Our test found the Econergy, a locally designed and made product, was at least three times more efficient than a standard electric cylinder. It's on a par with solar-power in terms of energy savings - and is likely to out-perform solar in less sunny parts of the country.” The same unit was awarded best product of the year in the Home/DIY category for 2009.
We wish to thank all our local suppliers and resellers for helping our project succeed.
Econergy has a Consumer Product Endorsement licence for the HP4000LT Heat-pump water heater.
For further information visit: www.econergy.co.nz
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