andrewNZ: The lleft hand unit is a ripple control relay. You have controled hot water
andrewNZ: Neither really.
It means you pay less for hot water heating, but the power company turns it off if demand is very high.
Its common as dog poo, there's no real problem with it.
bfginger: There is not much point having gas hot water if you don't have mains gas available. Bottled LPG costs the same as electricity and is only suitable for gas cooktops or off the grid use. Mains gas costs depends on where in the country you are. It should be cheapest in Auckland. The daily charge is a big part of the cost so it is usually only cost effective to have mains gas for cooktops in the home if you also have mains gas hot water or central heating.
There are online tools to find out whether there is a gas mains outside your house but they won't tell if you if it's a few houses away.
Old electric cylinders are uninsulated and leak huge amounts of heat. You can buy a polyester cylinder insulation wrap for $50 which will soon pay for itself. Copper pipe insulation tubes can also save 10c of electricity per day.
The way they call instant heaters "geezers" overseas is confusing as they also call their water cylinders "geezers". Instant gas hot water should be around 10% more efficient than gas hot water cylinders but I doubt they last as long so the total cost may not be so different. Gas hot water cylinders can't have cylinder wraps around them for safety reasons so they need to be well insulated. The level of insulation on new cylinders varies.
There are water heat pumps from better brands available.
Being on the right electricity plan will save you money. Plumbers may not be the best people to ask about the best choice of hot water supply. Every one I've known of is either fixated on the standard 180 litre electric or still thinks bottled LPG is cheapest. They're never interested in insulating pipes.
I don't think there is ever a bad time to talk about how absurd war is, how old men make decisions and young people die. - George Clooney
sep11guy: I have a feeling that my water wouldnt be controlled externally ( by power company etc ) , cuz i get only one reading on the bill from one meter ( shown on right ) :
but then I could be just assuming.
Electricity and electricity with supplementary systems like heat pumps and solar thermal have the advantage of being future-proofed for the arrival of affordable solar PV. With a timer or controller a tankload of hot water becomes very cheap.