Piped gas from the street vs heat pumps

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JayADee

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#322759 20-Sep-2025 09:30

Hi,

‘We’re thinking of selling our house and buying smaller both house and lot size.

A 92m2 house we’re looking at has piped gas from the street and a gas fireplace installed as a heat source.

What kind of costs are you looking at for running that as compared to say a heat pump? My present house has heat pumps and a modern wood burner.

Thanks!

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#3416555 20-Sep-2025 09:34

Beware that as fewer people use gas the prices are going up. I would plan to have the gas disconnected (which I've read on GZ can be quite expensive, thousands) and putting in a heat pump or two.

JayADee

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#3416616 20-Sep-2025 10:52

I ran it through AI using the present supplier’s prices from online and my present electricity prices and heat pumps and AI says

Heat pump is about 44% cheaper annually in this model.
The difference is mostly due to:
- Higher efficiency (COP 3.2 vs 85%)
- Lower energy input needed
- Lower fixed daily cost
Gas heating becomes costlier when:
- Daily fixed charges dominate
- Efficiency is lower than expected
If you're using heating every day, the difference widens further.

Yeah was really wanting heat pumps plus maybe a wood fire plus modern electric cook top (present one is gas).
Suppose if everything else works about the place we could swap it all out.

Is it hard to get the gas turned off and does that stop the daily charge those that have done it?

Jase2985

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#3416638 20-Sep-2025 12:11

Power and gas = 2x lines charges

Heat pumps give you 3-4x the heat out for the power in. ie 1kw in gives 4kw heat/cooling. Gas is less than 100% efficient.

Read from this post, contains info about them replacing a HWC and also removing their gas connection, there is post which outlines how much the gas meter removal cost later on @timmmay which is well less than the thousands you read.
https://www.geekzone.co.nz/forums.asp?forumid=141&topicid=296123&page_no=7#3414065

frankv

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#3416688 20-Sep-2025 12:50

Daily fixed charges are iirc about $1.50/day, so it costs me more for the fixed charges than the gas. (Gas hot water only, wood fire for heat).

Will be looking at either gas heating or a heat pump for heating next summer, so watching with interest.

Aucklandjafa

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#3416693 20-Sep-2025 13:18

frankv:

Daily fixed charges are iirc about $1.50/day, so it costs me more for the fixed charges than the gas. (Gas hot water only, wood fire for heat).

Will be looking at either gas heating or a heat pump for heating next summer, so watching with interest.

damn, I’m only paying 87cents inc GST/day. Who’s your supplier?

Mehrts

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#3416705 20-Sep-2025 14:17

$2 a day here for gas mains with Contact Energy in the Manawatu/Horowhenua area. It doesn't matter what provider you're with, they're all pretty much the same with their daily rates.

I'd love to get away from gas mains, but it's cheaper to use than electricity, especially for hot water heating.

If I was starting from scratch, I'd definitely be looking at a heat pump setup for water heating.

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JayADee

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#3416777 20-Sep-2025 17:40

Thanks for all the input. At my own house we have a wood fire with heat exchanger plus heat pumps for heating and lpg bottles for instant hot water and cook top (lpg is getting expensive). If we stay here I’m planning on installing a hot water heat pump and induction hob.

Reason I want to move is the lot size is getting too hard to maintain. Wouldn’t mind puttering around a smaller yard and spending a lot less time and money on yard maintenance.

I’m having a hell of a time finding a house the right size, in decent shape and that gets the sun. I wouldn’t have thought it would be this hard given I’m a bit flexible on house and land size but yeah it really is hard. Haaaarrrrd!

I’m going to look at this piped-gas-for-everything one tomorrow as I like the lot size and house location but I think the house is going to be too small- it’s only 92m2.

DjShadow

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#3416790 20-Sep-2025 19:10

When we moved into our current place there were 3 Gas Heaters, 2 non-flued and 1 in front of the old fire place in the lounge. The Lounge one when we tried it only heated about 1/4 of the lounge. Greater Wellington Regional Council at the time were offering loans repaid by rates to install cleaner heating so got a Heat Pump installed. Night and Day difference when it came to heating and much cheaper to run, also gave us an option to cool the lounge during the summer heat.

MichaelNZ

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#3416855 20-Sep-2025 23:38

JayADee:

A 92m2 house we’re looking at has piped gas from the street and a gas fireplace installed as a heat source.

What kind of costs are you looking at for running that as compared to say a heat pump? My present house has heat pumps and a modern wood burner.

I have a Rinnai gas heater in my home office. This is a modern electronic controlled and flued heater. Its very nice and effective. So there is nothing technically wrong with this path but you need to be aware of:

There is no point doing this by itself because gas is expensive to install. Also consider a gas cook top and water heating.
As others have said gas is increasing in price and may not be around in awhile so take your chances here.

If I were to do it again I would get a heat pump but this is only because its the pragmatic choice moving forward.

If you do decide to go the gas route get a Rinnai flued like mine and don't consider anything else.

FWIW I am on bottled LPG (2x 45kg) with Genesis as I am in a rural area.

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JayADee

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#3416860 21-Sep-2025 03:50

@MichaelNZ the house we’re looking at has piped gas heating, cooktop and hot water- a lot of the houses in the area I’m looking at are hooked up to piped gas. I’m considering that a drawback.

My preference is heat pumps, induction cooktop and preferably a hot water heat pump but I doubt many houses around here have one yet. I’m factoring in conversion costs.

In my own house if we give up looking for another, smaller one we’ll be switching away from bottled LPG for hot water and cooking sooner or later.

gregmcc

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#3416865 21-Sep-2025 07:30

I done some calculations a little while back on bottled gas(fixed gas fireplace) vs plug in electric heater vs heatpump

Gas fire place was about 5 times the cost of the heat pump, gas fire was about twice the cost of plug in electric heater

This was based on buying bottled gas and power from Genesis and excluded fixed daily charges and bottle rental.

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jamesrt

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#3416885 21-Sep-2025 09:32

gregmcc:

I done some calculations a little while back on bottled gas(fixed gas fireplace) vs plug in electric heater vs heatpump

@gregmcc; any chance that was an Excel (or similar) spreadsheet that you've still got available to share?

We're starting a new-build for the Kāpiti Coast - in the design process currently. My wife is very keen on a "feature" gas fire; I'm less keen on the expense and need evidence to support my argument...

DjShadow

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#3416886 21-Sep-2025 09:37

We’ve just ripped all our natural gas out and already seeing a big drop in cost in the Genesis app. With regards to your cooktop, I was keen to change to induction also but the plumber suggested we convert the cooktop to LPG so we can do induction at a later date so we took that approach. Now I’ve just got a 9kg swap-bottle sitting outside the kitchen running the stove and we don’t pay a monthly rental for it.

gregmcc

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#3416890 21-Sep-2025 10:00

No - Sorry not done in Excel

Some things you need to know to work it out

Cost of the gas per MJ of energy. Gas usage of the gas appliance as well as it's efficiency and it's rated output in KW and usage in MJ per hour, in my case:-

$175 for a 45kg gas bottle which has 2200MJ of energy (stated by the gas bottle supplier)

Heater is 5KW and efficiency of 73%, running on high setting this is 25MJ/hr of energy usage.

2200/25 (bottle MJ/usage per hour)=88hrs of run time per bottle

$175/88 (cost of bottle/run time per bottle)=$1.99 per hour for 5kw gas heater

For electric heating

for me my cost of electricity per KWH is $0.3088

for equivalent electric heating (assuming a standard resistive heater - such as a fan heater or similar = 100% efficient)

=0.3088x5 (cost per KWH x 5kw)=$1.54 per hour

For heat pump,

Heat pumps vary between 400%-800% efficiency this varies depending on make and model. I have taken a 5.1KW heating capacity heat pump and an efficiency of 500%

=5.1/5 (heating capacity/efficiency)=1.02KWH

Power usage=1.02x0.3088 (power usage x cost per KWH)=$0.32 per hour.

keep in mind these things :-

Gas fireplaces have a built in fan to circulate the heated air - the power usage for this has not been included.

Same for the electric fan heater - fan power usage not included

Heat pump power usage varies as it reaches it's set point temp it ramps down the power usage to hit the target before switching off, and actual power usage varies between makes and models for the same heating output.

so for us, electric fan heater is 5 times the price of a heat pump, 6 times the cost for a gas fireplace using bottled gas, the gas fireplace is over 20 years old and in the calculations it was assumed to be working as new based on manufactures specifications, so there could be more losses/gas usage due to age related inefficiencies.

jamesrt

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#3417135 21-Sep-2025 16:40

gregmcc:

No - Sorry not done in Excel

Some things you need to know to work it out

...

Thanks; that's very useful

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