High Power Bills? - Problem Solving Page

A few hints that you do not usually find elsewhere: This is intended to be used in addition to the advice given on the Energy Efficiency Advice Page and the EECA (Energy Efficiency Conservation Authority) site http://www.eeca.govt.nz

Electric Water Heater:

Almost every time there is a very high power bill that can not be explained, the problem is related to the hot water system when you have an electrically heated hot water system.
Your hot water cylinder has a overflow, sometimes this is in the form of a pipe that appears above the roof or sometimes it will go direct into a drain, try to see if there is any evidence of hot water discharge, a small amount of dripping from it is not unusual if the cylinder is heating the water, but this should only be occasional or if a large quantity of water is being heated.
If the hot water has not been used for some time the pipe/pipes above the cylinder should get cooler very quickly as you move away from the cylinder. If the pipe is still hot then it is a sign that hot water is being lost somewhere due to a leak or faulty valve or a running tap etc. Sometimes a valve may leak (may be intermittent) due to aging or dirt etc, this can be hard to catch if it happens only occasionally but can very quickly cause high power bills due to wasted hot water.
Un-lagged pipes can waste heaps of energy, especially if the length of pipe is a long run to where the hot water is required.
Try turning the cylinder off for 8 hours when no hot water is being used, does the water get cold? If so you have water or heat loss that needs rectified!
Try turning the cold water supply off to the cylinder when no hot water is being used. When the hot water has not been used for a while (at least 2 hours), feel the water pipe that comes from the top of the cylinder as far away as possible from the cylinder, up to a meter. The pipe should be cold, does the pipe heat up after the cold water tap is turned on? If so you very likely have got a water loss that needs rectified!

Showers:

Ensure the water flow is not too high (Hold a pot under the shower, it should fill slowly), try turning the water taps on less to reduce the water used per shower.
Shower flow ideally should be 6 - 12 litres per minute - If a one litre container fills in less than 6 seconds then the flow is greater than 10 litres per minute. Flow rate in Litres /per minute can be measured by dividing the time (in seconds) taken to fill a 1 litre container by 60.

Air conditioning:

Air conditioning is not expensive to run, especially on tepid days, but like anything the accumulative cost adds up, even if you are only spending $1 per day, it still is $30 per month if it is used every day.
Make sure the air filters are clean on the indoor unit, as efficiency will drop off if the air flow is impaired.
Check the outdoor unit, it should be clean and have clearance for good airflow.
Try not to increase the temperature too much, 18°C is an ideal temperature (especially if wearing warm clothing or thermals).

If the temperature is increased too much the air conditioning must work much harder, it will shift more air which creates a cooling effect (just like when turning a fan on when it is hot, you feel cooler). When you feel cooler, often you will increase the temperature, which then causes the air conditioning to increase the air flow, further creating that cooling effect. You can see how this turns into a vicious cycle!
Lowering the air temperature setting, lowers the fan speed required for efficient operation, thus less air flow to cool you down.

If the outside temperature is very cold use a fireplace (if you have one) instead, as the air conditioning is not as efficient when it is extremely cold. The air conditioning has to work much harder in cold conditions, as it has to provide more heat and there is less heat to extract from the outside air.
Is the air conditioning defrosting more than the occasional time (the internal unit will feel cold, as heat is being directed to the outdoor unit to melt the ice build-up) – this is a sign that system is struggling which will significantly increase the power use.

Security System:

The security system battery/batteries can drain lots of power if too old and faulty, does the system operate with the power removed, and does the power use drop when the power is off the alarm system? (Note: if you have any doubt about disabling the system or if there is a risk this testing may cause any problems, it would be best to consult the alarm service technician before beginning the test).
Get the system serviced if it has not been done regularly.
The life cycle of a system battery is approximately 4 years, if the battery is too much older (depending on your security system) the battery will likely be due for replacement.

Fridges and Freezers:

The seals on fridges and freezers are very important, if not in good order, these will allow heat to enter which will make the fridge/freezer inefficent.
Are you running unnessary fridges or freezers?
For more info see go to the Energy Efficiency Advice Page

Computers:

Computers that are left running all the time can be expensive approx $15 - $30 per month for a desktop pc even with the energy efficient set-ups.
The computer does not use much in standby.
For best power savings especially when not being used for long periods, shutdown completely and turn off power at the wall.
Laptops continually trickle charge batteries, while they are far more energy efficient than a desktop pc, it is best to not leave on all of the time. It pays to regally use the laptop on batteries to prevent overcharging of the battery (best to run down by about 5 to 10%, see instructions for laptop for what is appropriate battery care for your laptop).

Standby Loading:

Get into the habit of switching off appliances that are not being used.
How fast does the meter dial move when no one is using anything (Or it may be a flashing LED depending on the meter type), if it is moving steadily try the following test:

Turn off any air conditioning, water heaters and fridges/freezers before staring the testing (see note 1).
Switch off the circuit breakers one by one and/or remove fuses one by one (see note 2) until the meter dial or LED slows or stops, indicating a power decrease.
Leave off any circuits that cause a power decrease and find out what is not working when the fuse is left out. These will most likely be the appliance/s that are giving problems.
If there are multiple appliances then you will need to test them one by one as some might be ok. Test them by powering the appliance and noting if the power usage increases.

Note 1: It is ideal not to do this when the fridge/freezer is running, if you do this when the fridge is running, turn it off at the wall until the testing is finished (if the fridge is turned off then on very shortly afterwards, the compressor can stall, this is not good for the fridge and can cause a failure if the safety cut-out fails. The fridge should not increase in temperature for short periods especially if the door is not opened during that period. REMEMBER to turn back on fridges and freezers after testing is complete!)

Note 2: Fuses can be a shock hazard if the fuse wire is too long etc. Fuses are best removed and replaced with the power off for safety. Also it is important that the fuses are put back into the same holder as it was removed from, as the current rating is different depending on the circuit type, cable sizing etc.

Still No Joy?:

If you still have not tracked the cause of the high power usage (remember most times it is due to hot water losses) then doing daily meter readings while isolating various items is an effective way of tracking the problem.
There may be multiple issues, while not very common, be open minded.
Isolate either 1 item or multiple items, and using the method below to work out your daily cost, does the power use significantly drop, if the cost drops to what would be a normal cost, then the item isolated is likely to be the cause of your problem.

Meter Readings:

If you are experiencing excessive power usage, it is recommended to do your own regular meter readings e.g. I would recommend you do daily readings.
To calculate the power usage simply subtract the present reading from the previous reading, to get the cost of the power used multiply the power used by the unit cost (usually around the $0.18 per Kilowatt hour*). E.g. if the previous reading was 123456 and the present reading is 123654 the cost would be (123654-123456) x 0.18 (if the unit cost is 18 cents per kilowatt) = $35.64 .The approx monthly cost would be able to be calculated by multiplying the units used x (30/[time period in days]) + the monthly supply charges**!
To calculate the power used since the last power bill simply subtract the present reading from the previous reading indicated in the last power bill (this may be on the back of the bill or another page with the costing breakdowns). To get the cost of the power used multiply the power used by the unit cost (usually around the $0.18 per Kilowatt hour*). Remember to work out the total cost of the power bill add on the supply charges (and any other charges that are usually on your bill).

*Note: Subject to change, see your power bill to get the correct amount!

**Note: The supply charge which is approximately $1 per day for domestic users (again see your power bill to get the correct amount!).