money tree said:
hanrahan, if you run your A/C off any other tarriff than 11 you will be heavily fined.
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Your electricity distributor can generally approve non-standard uses of tariffs. In Queensland you can certainly run clothes dryers, domestic freezers, dishwashers, swimming pools and the like on off-peak if you want to PROVIDED THAT there is no means of switching it over to the continuous supply when the off-peak is off. The appliance will need to be permanently wired in (not plugged in) to meet this requirement. To comply with the Wiring Rules this generally precludes the connection of anything "portable".
It would be unusual to connect an A/C to an off-peak tariff but some distributors may approve it. The case would certainly be enhanced for approval if there was a technical basis such as a high thermal mass in the house which limits temperature fluctuations thus not requiring 24-hour supply to the A/C. You would have to ask the electricity distributor what its view is since it will vary enormously between states and even between distributors (note: distributor as opposed to retailer although retailers also have their own rules) in the same state.
In Victoria some distributors offer discount 24-hour supply for A/C used for heating during Winter with standard rates applying in Summer. This makes the installation of a reverse cycle unit for both heating and cooling very attractive rather than using gas heating. You can also connect a bathroom Tastic to this (but only if A/C is also connected).
In Tasmania A/C is actually quite common despite the minimal need for cooling since it is by far the cheapest form of heating (and heating can be a significant cost in Tas). Aurora Energy offers a discount year-round tariff (T42) commonly known as "HydroHeat" (a term with which the general public in Tas is very familiar) for any permanently connected electric heating system (doesn't have to be A/C) installed in the main living area provided that it meets some simple technical requirements. Other heaters (except Tastics) anywhere in the house can also be connected to this as long as the main living area is connected as can smaller (not off-peak) hot water heaters. Can also be used to boost solar hot water etc. This is a 24-Hour tariff priced between the standard rate and the off-peak rates.
Off-peak conditions vary somewhat around the country but briefly it's as follows. The night only rate is always the cheapest with the extended hours off-peak being priced somewhere between that and the 24-hour rate.
Qld - Two rates either "night only" or for about 18 hours per day (minimum time, it's generally longer).
NSW - Very similar to Queensland.
Both NSW and Qld use remote switching via high frequency injection and as such the actual times will vary a little from day to day according to actual power demand. The other states use timers installed at the switchboard - these are not adjustable except by the electricity supplier and are not generally adjusted for daylight savings.
Vic - Night only for hot water but an afternoon boost is available for space heating only. Different rate depending on how long it is on for at night (6 or 8 hours) and some distributors / retailers also offer a 4 hour rate which is
very cheap for boosting solar hot water. Most modern hot water heaters will be fine on 6 hours so don't pay for 8 hours unnecessarily. To check, divide the element rating in Watts (eg 4800W which is 4.8kW) by the size of the water tank (eg 315 litres) and if the number you get is close to 15 (or higher) then 6 hours will be fine. Typically the tank would be either 250l/3600W, 315l/4800W or 400l/6000W which are all fine on 6 hours. If it's 315 litre / 3600W etc then you need the 8 hours.
Tas - Night only (9 to 11 hours which is relatively long) or with an afternoon boost at a higher rate (usually about 13 hours per day in total but if you ask nicely and have a sensible reason then they'll generally be reasonable and give a bit more time). Either rate can be applied to hot water (including solar boost and heat pump water heaters),
storage space heating or anything else that is approved. Not for A/C etc (use HydroHeat).
SA - Night only. Used mainly for hot water. Not sure how flexible they are about other uses.
WA - Has an off-peak tariff in the SWIS (South-West Interconnected System - Perth and greater surrounds) area for 6 hours (night only). Not sure about their attitude to non-water heating uses.
All states - if you have a TOU (Time Of Use) meter where the rates vary according to the time of the day (including Pay As You Go meters in Tas) then you could have your own timer and set whatever times you want according to how much you're prepared to pay. If doing this with hot water etc. then remember that it will run flat out when first switched on so start at a very cheap period and if you want to extend the time then extend the end (when it will often have turned itself off via the thermostat anyway) rather than bringing forward the start.