Bottled gas price vs Electric water heating / washing machine

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gzt

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#322973 11-Oct-2025 14:45

I have gas rinnai instant hot water installed five years ago. Bottled gas price is currently $175 per 45kg gas + $11.50 month bottle rental for two bottles I'm paying around 25c per kwh for electricity.

My washing machine can use the gas heated hot water, or use its own element to heat cold water internally.

Using Google AI and assuming a starting water temperature of 10deg C, and heating 100 liters to 50 deg C - $1.55 for gas (excluding bottle rental) and $1.15 for electricity (excluding line charges etc). Does that look right?

pih

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#3424149 11-Oct-2025 17:44

25c/kWh is pretty cheap. If you can take advantage of free power with your power company it becomes a no-brainer, but what you you have said is otherwise about right.

farcus

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#3424153 11-Oct-2025 18:00

those look like Genesis prices??
If you have your electricity with them and pay by direct debit those prices drop to $155 per refill and $10 for 2 x bottle rental

cddt

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#3424185 12-Oct-2025 07:45

A quick search shows there is approximately 625 kWh in a 45 kg gas bottle.

$175 / 625 = $0.28 per kWh, so slightly more expensive than your electricity price of $0.25 per kWh.

This doesn't take into consideration appliance efficiency.

My referral links: BigPipe | Mercury

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#3424350 12-Oct-2025 14:37

Thanks for that. Googling tells me 98% efficiency for non-storage electric more or less matching my washing machine internal heating. Tells me about 80% efficiency for gas instant. Extra bonus for electric there.

If it worked out the same or similar I'd use electric in preference anyway for less calls and switchovers when s bottle runs out always in the middle of a shower, and reducing non-renewables/co2.