Aussie Home LPG Gas Information
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What Do You Know About Your LPG Gas Supply
We have created this page to share interesting information which most of you are unaware of but commonly are in search for. Hopefully this information will serve as a starting point when comparing appliances that run off gas to those powered by electricity.
How Much Energy Is There In A LPG Gas Bottle?
This has been a common question asked by our clients over the years, when they are wanting to compare gas to electricity. Here are some simple facts about LPG gas versus electricity:
- 1 kg of LPG gas contains 50.4 MJ [Mega Joules] of energy
- 1 kWh of electricity = 3.6 MJ of LPG gas
- One 45 kg LPG gas bottle [45 kg x 50.4 MJ = 2268 MJ of energy
- Other bottle sizes are: 9 kg = 453. 6 MJ : 2 x 45 kg bottles = 4536 MJ
Other useful information:
- Green House Gas [CHG] Emissions 3.6 MJ Gas = 0.2 kg CHG
- CHG for coal fired electricity = 1.4 kg CHG
- 1000 Mega Joules = 1 Giga Joule
- 1 x 45 kg LPG gas bottle = 630 kWh of electrical power
- 1 X 45 kg LPG gas bottle contains 88 litres of LPG [Propane] gas
- Dimensions of a 45 kg bottle are height 125 cm X diameter 37.5 cm
- 1 litre of LPG gas weighs 0.51 kg
- 1 kg of LPG gas has a volume of 1.96 litres
- 1 MJ of LPG gas equals 948 BTU [Imperial system of measurement]
- Weight of empty 45 kg LPG gas bottle [Tare weight] 33 kg [Older bottles more, newer less]
Download the above information as a quick LPG 45 KG GAS BOTTLE INFORMATION GUIDE
What Is Cheaper Per Unit Of Energy, Gas Or Electricity?
Let us say you pay $135 for a 45 kg bottle of LPG gas, which has the equivalent electrical energy of 630 kWh.
Maths being $135 / 630 kWh = 0.21 cent per kWh of comparable electrical energy. So are you paying more or less than this 21 cent per kWh figure?
The above does not take into account the efficiency of any appliance [most appliances are not 100% efficient, see the star ratings for more information] and other operational variables such as ambient temperature. The figure is a starting point for further investigation.
How Long Does A 45 kg LPG Bottle Last?
Firstly you will need to know how much gas your appliance uses in MJs per hour. This may be stated on the appliances Australian standardised 'energy label'. If your appliance does not have an energy label then the required gas maybe stated in the specification section of the instruction manual, or on the appliances information plate.
The following example uses a gas heater with 12.6 MJ consumption of gas per hour. The consumption figure assumes it is on full or high. This does not take into account any thermostatic control, which will reduce the gas used and therefore extend the hours of operation.
1. Divide the total energy within a 45 kg bottle 2268MJ by the heaters hourly rating of 12.6 MJ/h
2. A full gas bottle will power our heater on full for 180 hours.
3. If the gas heater is operated for 3 hours per day, the gas would last for approximately 2 months. Maths being 180 hours / 3 hours per day = 60 days thus 2 months.
How Many Bottles Will I Need A Year?
For this example we will use a gas water heater. The energy label clearly suggests a yearly gas consumption of 22,200 MJ per year.
This is divided by 365 resulting in an average daily use of 61 MJ per day.
The number of LPG bottles required per year can be easily worked out by dividing the suggested annual gas consumption of the appliance by the total amount of gas an LPG gas bottle contains.
22,200 MJ / 2268 MJ = 9.78 bottles therefore 10 bottles per year are needed.
What we are not told by this label is the number of MJs this appliance uses on an hourly basis.
Checking The Level Of LPG Gas In A Bottle
To check the level of LPG gas in a bottle, it is a fairly easy process.
If you do not know the science of LPG gas, you may be interested to learn about how it is stored.
LPG is stored under pressure as a liquid. This gas in effect boils at minus forty two degrees, to turn from liquid into a gas. During this conversion of liquid to gas, there is considerable heat drawn from the steel wall of the bottle and the ambient air outside of the bottle. Thus the side of the gas bottle will feel colder where the liquid LPG gas is inside.
The above is even more obvious when you are using gas, as more of the liquid is turning to gas at that time. Under some circumstances where gas usage is high, ice can form on the outside of the gas bottle or the fittings.
If there is a situation where no matter how hard you try, you cannot feel the difference on the outside of the LPG gas bottle, try the following.
Pour hot water down the outside of the gas bottle. Do not use boiling water and take the necessary safety precautions not to injure yourself or your helper. You will need to pour enough hot water to heat the steel wall of the bottle a few degrees. The steel above the level of the gas, will retain it's heat longer than the level of steel where the gas is inside the bottle. Hence it will feel warmer above the gas and cooler below the level of gas. You may need to wait a few seconds or you may notice a line of condensation, corresponding to the level of gas in the bottle.
What Is The Cost Of A 45kg LPG Gas Bottle?
This can vary quite a lot in price, as delivery costs can really hike the total cost! The price we pay for bottled LPG gas currently [October 2011], is $130 delivered. There is a bottle rental of $30 per year, per bottle.
You may get a better deal by bundling the gas with your ELECTRICITY PROVIDER. This is not the case always, so it pays to shop around.
Flueless / Unflued Gas Heaters
We are often asked questions on whether flueless / unflued gas heaters are healthy or unhealthy.
Are You Aware You Need Adequate Cold Air Ventilation When Operating These Heaters?
In most manufacturer's documentation it states adequate ventilation is a requirement! How much ventilation though and what type on a cold night, results in most homes we have visited having NO VENTILATION!
Read our blog entry FLUELESS HOME GAS HEATERS & WINDOW VENTILATION. More information on unflued gas heater residential regulation, can be found on our LINKS page.
What Is The Open Window Requirement?
The open window requirement means you get the required amount of fresh air into the room, when you have no forced air flow such as a ducted fan system.
The required ventilation is based on 5% of your floor area [when a standard ceiling height is used]. Use the table below to give you an idea of a comparable window size that you should have open, to supply this required ventilation.