Is gas hot water cheaper per unit than a standard HWC?

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#3453074 14-Jan-2026 21:51

I've got a Rinnai EF24 continuous gas unit with two heat exchangers (which is supposed to be more efficient) - mainly because we had someone in our granny flat who used to either use all the hot water or complain they didn't get enough. We have a big freestanding oven with gas hobs so replacing both with Induction + HP WH would be a huge upfront expense, so we'll be sticking with gas until one of those systems fails and cannot economically be repaired or replaced.

Did get stung by Mercury this last month as they finally decided to do an actual meter reading.. ouch!

mudguard

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#3453089 15-Jan-2026 07:15

insane:

Did get stung by Mercury this last month as they finally decided to do an actual meter reading.. ouch!

Ouch indeed! Is there a reason it was so long between reads? I know it's probably not as easy but it would be nice for gas to have a smart meter too.

johno1234

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#3453090 15-Jan-2026 07:22

Mercury replaced our gas meter last year presumably with a smart one?

mudguard

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#3453092 15-Jan-2026 07:53

johno1234:

Mercury replaced our gas meter last year presumably with a smart one?

Ah right, to be fair I've not looked that hard. I just assumed that because the weekly usage email never included the gas portion, that it didn't have any smarts.

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#3453189 15-Jan-2026 08:54

Don't forget to factor in increased health costs, especially if you are not always on the ball about ventilation. The health hit from gas is no joke. Google "indoor air pollution gas appliances" and you'll see what I mean. A 2025 NZ study indicates 208 premature deaths per year from gas stoves, and 775 respiratory hospitalisations.

AklBen

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#3453197 15-Jan-2026 09:56

^ there are multiple reasons why I want to get rid of our gas hob and that's a very good one.

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#3453336 15-Jan-2026 14:22

scuwp:

They will have to pry my instant gas hot water system out of my cold dead hands...

The trouble is it isn't instant, well not with the two systems I use on a semi regular basis. One of them takes nearly a minute at full flow to get hot water in the bathroom. The other one is marginally better. YMMV depending on where the heater unit is sited.

I dislike them with a passion. I'd never have one. Each to their own I guess.

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AklBen

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#3453338 15-Jan-2026 14:23

Technofreak:

scuwp:

They will have to pry my instant gas hot water system out of my cold dead hands...

The trouble is it isn't instant, well not with the two systems I use on a semi regular basis. One of them takes nearly a minute at full flow to get hot water in the bathroom. The other one is marginally better. YMMV depending on where the heater unit is sited.

I dislike then with a passion. I'd never have one. Each to their own I guess.

When water was 'free' this wasn't an issue. Now we're (in most places) fully aware of our water consumption on a monthly basis this has become more and more of a gripe.

scuwp

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#3453359 15-Jan-2026 15:47

Technofreak:

scuwp:

They will have to pry my instant gas hot water system out of my cold dead hands...

The trouble is it isn't instant, well not with the two systems I use on a semi regular basis. One of them takes nearly a minute at full flow to get hot water in the bathroom. The other one is marginally better. YMMV depending on where the heater unit is sited.

I dislike then with a passion. I'd never have one. Each to their own I guess.

Don't have that issue at all, although I think you may be taking the word 'instant' too literally. There is always a delay to get the hot water from where it is, to where you want it. The further away the tap is from the source, the longer it takes to get there. If you had an electric storage system in the same location, I would wager the delay would be around the same. Also depends on the flow rate. The original taps in our house are unrestricted (before the WELS ratings came into force), they flow at about 12L/min. Taps we have replaced with WELS restrictions (because we have no choice) are only about 6L/min. Hot water takes longer to appear at those taps.

However this is all off topic. Thanks to those that provided some rational math's and examples, it was comforting to know that gas isn't yet overwhelmingly more expensive.

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Kickinbac

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#3455120 22-Jan-2026 17:04

Ikea do cost effective induction hobs with 5 year warranty. Apparently made in Germany by Electrolux.

An induction hob (generally) needs a 32 Amp power supply from the switchboard. Plus another 32 Amp power supply for the oven.

Each house differs as to the complexity and cost of getting this power feed installed so get sadvice form an electrican.

Most hot water heat pumps only need a 10 amp power supply. Most houses this would be 2.5mm feed from the DB.

There are some cost effective hot water heat pumps available now from Gree, Midea and Carrier.

The best hot water heat pumps have CO2 refrigerant like Reclaim, Panasonic and Sanden. They can be expensive but very quiet and efficient. Daikin just released a CO2 version. Mitsubishi Electric have various options too.

johno1234

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#3455143 22-Jan-2026 20:13

Technofreak:

scuwp:

They will have to pry my instant gas hot water system out of my cold dead hands...

The trouble is it isn't instant, well not with the two systems I use on a semi regular basis. One of them takes nearly a minute at full flow to get hot water in the bathroom. The other one is marginally better. YMMV depending on where the heater unit is sited.

I dislike them with a passion. I'd never have one. Each to their own I guess.

It just means instant from cold to hot at the source. Same travel delay as an HWC at the same spot of course.
I do prefer the califont other than the high fixed gas charges. Kids away at uni most of the time these days but when they’re home it’s nice to never run out of hot water and the marginal cost is still less than resistive electric.

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mudguard

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#3455418 23-Jan-2026 13:00

johno1234:

I do prefer the califont other than the high fixed gas charges. Kids away at uni most of the time these days but when they’re home it’s nice to never run out of hot water and the marginal cost is still less than resistive electric.

As a rule I do prefer the califont as well. But I can see the cost spiraling. Especially as mentioned we are household of two so the daily charge is between 30-50% of our actual bill.

AklBen

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#3455459 23-Jan-2026 16:39

Now spending a minimum of $100 on fixed charges is pretty lame.

Scott3

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#3455481 23-Jan-2026 18:47

Kickinbac:

Ikea do cost effective induction hobs with 5 year warranty. Apparently made in Germany by Electrolux.

An induction hob (generally) needs a 32 Amp power supply from the switchboard. Plus another 32 Amp power supply for the oven.

Each house differs as to the complexity and cost of getting this power feed installed so get sadvice form an electrican.

Most hot water heat pumps only need a 10 amp power supply. Most houses this would be 2.5mm feed from the DB.

There are some cost effective hot water heat pumps available now from Gree, Midea and Carrier.

The best hot water heat pumps have CO2 refrigerant like Reclaim, Panasonic and Sanden. They can be expensive but very quiet and efficient. Daikin just released a CO2 version. Mitsubishi Electric have various options too.

Many oven's only require 16A single phase.

When we upgraded from ceramic to induction, we used the existing 32A feed (which previously did both the cooktop and oven) to feed just the induction cooktop. and the oven went onto a new feed (only needed 16A, but the sparky put a 20A breaker on it). New wire run was at least triple the distance of the old run, but that route enabled us not to cut any walls open.

Should note that induction cooktops restricted to 16A draw (they just don't let you turn as much stuff on at the same time) do exist for applications where a wiring upgrade is not viable (for replacing an ceramic cooktop).

Bowie

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#3455544 24-Jan-2026 07:20

Wouldn't gas bottles would be cheaper than gas main from the street?

If you go the solar power way.

You would only benefit if you were home during the day to use the free power. Getting batteries for storage would be very costly so I am told from the neighbor's who have solar.

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