Monday, August 13, 2007

Our family is reinstaling a new solar water heating system

Despite our previous negative experiences with solar water heating, our family is about to install a new solar water heating system on our house. More about this soon.

Far from being negative about the future of solar water heating in New Zealand, I am all for solar water heating. I believe that every NZ house with a sunny disposition should be employing solar energy capture systems like solar water heaters to reduce expenditure on household energy while improving quality of living.

Having said this, there is nothing to be gained and much to be lost if householders install poor quality systems that do not go the distance. Even a quality system will not perform or last if the workmanship of the installation is poor. There are good systems and quality installers out there; It is just a matter of doing your research carefully and selecting the best system for your requirements.

Please peruse this website using the search functions to in the right hand column to find your way. I strongly recommend that you take time to read the BRANZ reports that are on this website and read the responses on this website.

It is clear that pressuring the industry to bring down prices has been counter-productive. Low cost items simply may not be of a quality sufficient to withstand half a dozen years of being battered, soaked, frozen and roasted in the typical NZ roof setting - let alone durable enough to keep working for 20 years!

Energy conservation in the home is a multi-factorial exercise, since it is total energy consumption that is the key to reducing a family's energy costs - and saving the planet - of course!

As part of our family's programme to reduce our carbon footprint, we have amped up the insulation of our house by filling the internal cavities of the walls of our old house with foam insulation. For more information about this energy conservation measure, go here. However; in recommending this energy conservation measure, our family does not recommend this firm. They were very good on the sales pitch, but very poor on the after sales handling of us. Why do so many NZ companies keep letting themselves down on their customer service?


Stephen said...

Hi Gary, I would love to hear about your progress on this. Have you been looking at an evacuated tube solution?

Anonymous said...

Thanks for the info, I was thinking of having this done on our house (22 years old), the existing wall insulation (pink batts) is so thin and loose fitting I doubt its having much effect - yeah another shoddy installation job.

Does your house feel much warmer ??


Chris said...

Hi! Have just been looking at your website and feel I should comment.

I also think flat plat panels should not corrode; my previous house
has a set that I made well over 20 years ago and they still work just
fine. No corrosion!

But they are not a patch on the new ones at the new house (both near
Coromandel Town) which are Vacuum Tube type. We installed about twice
the recommended area (9 squ meters) last October. They are coupled up
to a 400 litre hot water cylinder. There is an electric boost which I
trust works; but I havent turned it on yet, and it is nearly mid
winter! We are pumping excess heat thru our concrete floors. Even now
on a fine day there is enough to provide a little warmth. During the
heat of the summer the cylinder would be up to 90 degrees plus by mid
morning. To keep the entire from boiling (or shutting down) I pumped
it thru a set of pipes on the rock, well down under the house, and
even now the basement is really cosy warm as this heat trickles back up.

The panels empty if the power fails and then the controller waits
until night to refill. This is because without water being circulated
to cool them, they boil. After they emptied when we had a power cut a
of couple months back, I noted the reading: 220 degrees Celsius!
Pumping cold water into panels this hot would put a lot of stress on
them and should be avoided. It also shows just how hot they can get.

Flat panel types can and do boil the water, but only under the best of
conditions, because the heat losses from inside the panel will match
the input of the sun quite quickly. Particularly under poor conditions
of cold air temperature, wind, and patchy sunshine, when the
temperature that this occurs can be so low that it is lower then the
cylinder. And as you say, a bit of corrosion just adds to it's woes!

Vacuum tube type have so little loss that they keep right on absorbing
more heat just about regardless of the air temperature, wind, and
remarkably even in quite overcast conditions. Vacuum tubes insulate
the water that you are heating on the same principle as the humble
Thermos. It's a bit like trying to keep your tea hot by inverting a
glass jar over it, compared to putting it into a Thermos flask!

I used standard commercial panels, had the cylinder built to my spex,
and have coupled it all up in an entirely different and much simpler
way than any of the present normal standards. It works very well.
Right now I am building an ultra high efficiency wood-fired boiler to
boost the system along in really cold patches. Presently there is no
other form of heating.

I would recommend for anyone else to install as much panel and as
large a cylinder as they can afford, use a closed loop system, and use
FAR more insulation around the Hot water cylinder than the standard
that they come with. I put an extra 50mm of batts, but the losses are
still MUCH too high. 100mm of polyurethane foam would do a much better
job. If they can make use of the excess heat in the summer by putting
it into a swimming pool or whatever, so much the better.

And I think most people recover from the initial cost quite quickly
(See it as just part of the cost of building a house, like Council
Fees and other Exorbitant-but-Unavoidable costs!) and just LOVE having
all the hot water they want. We noticed when we first got solar hot
water that we used so much more of it! The new house is made to be
energy efficient, is delightfully comfortable, and we are very pleased
with it. Payback time can't really be calculated because it does so
much more than reduce the cost of electrically heating the water.
Including saving the planet! Well, just a teeny bit, but it all helps!
Solar and wind electric power is next on the list!


Chris Ogilvie,
1800 Wyuna Bay Road,

07 866 8582

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