Water heating systems tool

Compare the upfront, annual running, and lifetime costs of hot water heating systems for your household. Hot water heating accounts for around 30% of the average household energy bill – choosing the right system for your needs can make a real difference, especially on your wallet.

You’ll need to grab your power bill – then let’s get started.

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Which of these best describes your situation?

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Where do you live?

What's your current water heating system?

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What's your shower's flow rate To find out your shower's flow rate turn the shower on and fill a 10 litre bucket for 30 seconds at normal showering temperature. At the end of the 30 seconds measure how much water (litres) is in the bucket and multiply by two to get the shower flow rate per minute. If your flow rate is more than 9 L/min, we recommend installing an efficient shower head. If you don't currently have a shower or are not sure, select "Don't know" and we'll use the average flow rate of 11 L/min.

Approximately how many showers does your household have each day? If your household has more than one water heating system, tell us how many showers you have each day just for the system you have selected. If you don’t have a current working system, tell us how many showers you would have for the system you are thinking of installing.

What is the average length of each shower in your household? If your household has more than one water heating system, tell us the average length of each shower for the system you have selected. If you don’t have a current working system, tell us the average length of each shower for the system you are thinking of installing.

Approximately how many baths does your household run each week? For this tool think of one bath as a near full bath. If you take smaller baths then calculate the number of near full baths e.g. if you have four half full baths a week, enter two baths.

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What is your electricity tariff (cents/kWh)? Your electricity tariff will be listed on your power bill (cents per kWh). Do not include any daily fixed charges. Include your usage charge (cents per unit/cents per kWh), Electricity Authority Levy, and any network charges.

Prompt payment discount (%)? Check your power bill to see if you receive a prompt payment discount, enter the percentage.

Does this include GST? Check your power bill to see if GST is included. If you don't know, select 'Yes'

Type of gas? If you are not sure which type of gas you have, check to see if it is noted on your power bill, or contact your gas supplier. Some rules of thumb you can follow: if you live in the North Island and have piped gas it will be natural gas, otherwise you will have LPG bottles. If you live in Christchurch and have piped gas it will be reticulated LPG, if you live anywhere else in the South Island you will have LPG bottles.

Do you use gas just for water heating? If you choose 'Yes' all fixed gas charges or bottle rental fees will be included in the calculation of the water heating costs. If 'No' only the variable gas charges will be included in the calculation of the water heating costs.

What is your gas tariff (cents/kWh)? Your gas tariff will be listed on your power bill (cents per kWh). Do not include any daily fixed charges. Include your usage charge (cents per unit/cents per kWh), Gas Industry Company fees, and any network charges.

Cost to refill 45kg LPG bottle ($)? Your gas tariff will be listed on your power bill (cents per kWh). Do not include any daily fixed charges. Include your usage charge (cents per unit/cents per kWh), Gas Industry Company fees, and any network charges.

Daily fixed charge for gas ($/day)? Your gas charges will be listed on your power bill. If you don't know your charge leave in the default value.

Annual LPG bottle rental fee ($)? If you don't know the fee, leave in the default value

Do these charges include GST? Check your power bill to see if GST is included. If you don't know, select 'Yes'

Prompt payment discount (%)? Check your power bill to see if you receive a prompt payment discount. enter the percentage.

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What is the approx volume of your hot water cylinder? The volume will usually be listed on the cylinder.

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Where is your hot water cylinder located? Location makes a difference to running costs because it takes more energy to heat a cylinder located in cooler locations (e.g. outdoors).

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When was your cylinder manufactured? The year of manufacture will usually be listed on the cylinder.

Is a cylinder wrap fitted? A cylinder wrap is placed around your cylinder and helps keep the heat in. It will be obvious if you have one or not.

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Is your solar water heating system ENERGY STAR® qualified?

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Edit your details

Water heating system options

See how different water heating systems compare. Customise the results by selecting 'Edit details' under each system and answering a few questions. Blank fields indicate that more information is required, enter this by selecting 'Edit details' under each system.

Sort your results by selecting the column headings. Use the buttons at the end of the tool to print or email a copy of your results.

Customise your results

	Water Heating System	Upfront Costs Upfront costs = purchase + installation costs. A range is shown as there can be differences in the size and quality of the system and complexity of installation.	Yearly Running Costs Running costs = the likely cost to run the water heating system each year. This is calculated based on how much hot water you use and the system type and efficiency.	Lifetime Costs Lifetime costs = running costs + purchase and installation costs, over ten years (we have assumed a life span of ten years for the calculations in this tool, although many systems may last much longer). We have also allowed for the cost of interest, should you take out a loan to pay for it, or the missed interest earnings if you had left the money in the bank instead. The lower price is based on buying and installing a highly efficient system at a low price. The higher price is based on buying and installing a low efficiency system at a high price.
	YOUR CURRENT SYSTEM {{ result.name }} Edit details	Upfront costs	Yearly running costs {{ result.running_cost_range \| filterDisplayPriceRange }}	Lifetime costs {{ result.lifetime_cost_without_upfront_range \| filterDisplayPriceRange }}
Select / deselect row	{{ result.name }} Edit details	Upfront costs {{ result.upfront_cost_range \| filterDisplayPriceRange }}	Yearly running costs {{ result.running_cost_range \| filterDisplayPriceRange }}	Lifetime costs {{ result.lifetime_cost_range \| filterDisplayPriceRange }}

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The water heating systems tool is designed to compare water heating systems for your household.

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