Electric Hot Water System Replacement Guide

Replacing an electric hot water system is usually more straightforward than changing from gas, solar or heat pump, but it still needs the right checks before you buy online. Tank size, element rating, physical dimensions, access, valves, drainage, electrical supply and compliance requirements all matter. At Hot Water Outlet, you can compare supply-only hot water systems online, including electric hot water systems, instant electric hot water systems, heat pump hot water systems and compatible valves, pipework and fittings.

Quick Answer

Before replacing an electric hot water system, check the existing tank size, element rating, dimensions, location, electrical circuit, valves, drainage and access.

A like-for-like electric hot water system is often the simplest option when the existing setup has worked well and the property’s electrical supply is suitable.

A heat pump hot water system may be worth comparing if you want a more efficient electric option and have suitable outdoor airflow, drainage, noise placement and electrical setup.

An instant electric hot water system may suit selected small point-of-use applications, but it is not always suitable as a whole-home replacement because it can require significant electrical capacity.

Supply-only pricing is not the same as total installed cost. Installation, electrical work, plumbing labour, valves, fittings, pipework changes, drainage, old unit removal, disposal and compliance upgrades may all be separate.

Electric Hot Water Replacement Checklist

Step 1: Check the Existing Electric Hot Water System

Start by identifying the current system.

Check:

• Brand

• Model

• Tank size in litres

• Element rating

• Indoor or outdoor rating

• Approximate age

• Serial plate details

• Installation location

• Connection positions

• Existing valve setup

• Existing electrical supply

If the existing electric system has performed well, a similar-sized replacement may be a practical starting point. If it has been running out of hot water, leaking, overheating, tripping power or failing to recover fast enough, the replacement size or setup may need to be reviewed.

Step 2: Choose the Right Tank Size

Electric storage systems are sized in litres. The right size depends on the number of people, bathrooms, shower habits, baths and whether hot water is used heavily at the same time.

A smaller tank may be cheaper upfront but may run out of hot water quickly. A larger tank may provide more hot water but needs more space and may cost more to buy and run.

Do not choose based only on the old tank size. If the household has changed, the replacement size may need to change as well.

Step 3: Check the Element Rating

Electric hot water systems use an electric element to heat the water. The element rating affects recovery time and electrical requirements.

Common electric hot water element ratings may include:

• 1.8kW

• 2.4kW

• 3.6kW

• 4.8kW

A higher-rated element can heat water faster, but the electrical circuit must be suitable. Do not assume the existing circuit can support a different element rating.

Before ordering, check the existing system label and confirm the electrical requirements with a licensed electrician where needed.

Step 4: Measure the Existing Unit

Electric hot water tanks can have different dimensions even when they hold the same number of litres.

Measure:

• Height

• Diameter

• Width

• Depth

• Clearance above the unit

• Clearance around valves

• Distance to walls

• Doorway width

• Cupboard opening

• Safe tray size if indoors

• Base or slab size

• Access path to the unit

A replacement system may be the same capacity but wider, taller or have different connection points. This can affect whether it fits the existing space.

Step 5: Check Indoor vs Outdoor Suitability

Electric hot water systems may be designed for indoor, outdoor or specific installation locations. Always check the product details before buying.

Indoor installations may require:

• Safe tray

• Drainage

• Access for servicing

• Correct clearance

• Protection from water damage

• Suitable electrical isolation

• Temperature control

Outdoor installations may require:

• Suitable base or slab

• Weather exposure suitability

• Drainage

• Safe relief valve discharge

• Access for servicing

• Correct pipework and insulation

Do not assume an indoor unit can be installed outdoors or an outdoor unit can be installed inside a cupboard without checking suitability.

Step 6: Check Access for Delivery and Replacement

Electric hot water tanks can be heavy and awkward to move, especially larger units.

Check:

• Driveway access

• Side access

• Gates

• Stairs

• Tight pathways

• Retaining walls

• Steep blocks

• Apartments and lift access

• Balcony access

• Garage clearance

• Distance from delivery point to system location

• Whether the old unit can be removed easily

Supply-only pricing does not include difficult access, specialist lifting, crane work, old unit removal or extra labour unless specifically shown at checkout or quoted separately.

Step 7: Check the Electrical Supply

Replacing electric hot water may require electrical checks, even when replacing like-for-like.

Check:

• Existing circuit size

• Element rating

• Switchboard capacity

• Circuit protection

• Isolator location

• Timer setup if applicable

• Off-peak tariff arrangement if applicable

• Whether the existing circuit is safe and compliant

• Whether the replacement unit has different electrical requirements

Electrical work must be completed by a licensed electrician.

If you are moving from a smaller tank to a larger tank, changing element rating, moving the unit location or changing tariff setup, extra electrical work may be required.

Step 8: Check Off-Peak, Controlled Load or Timer Setup

Some electric hot water systems are connected to off-peak or controlled-load power. Others may run on a standard circuit or timer.

Before replacing the unit, check whether your existing system is connected to:

• Off-peak tariff

• Controlled load

• Timer

• Solar diverter

• Standard power circuit

• Booster switch

This matters because it can affect recovery time and how the system heats.

For example, a system on controlled load may only heat during certain periods. If the tank is too small for the household, it may run out before the next heating period.

Step 9: Check Drainage and Relief Valve Discharge

Electric hot water systems need a safe discharge point for relief valves. Indoor systems may also need a safe tray and drain.

Check:

• Existing relief valve drain

• Safe discharge point

• Safe tray drain if indoors

• Whether discharge could damage flooring or walls

• Whether drainage is blocked or poorly positioned

• Whether pipework needs upgrading

• Whether the replacement system changes valve locations

Poor drainage can cause water damage or compliance issues.

Step 10: Check Valves and Fittings

Electric hot water replacement often requires more than the tank itself.

You may need compatible valves, pipework and fittings, such as:

• Tempering valve

• Pressure limiting valve

• Duo valve

• Expansion control valve

• Isolation valve

• Non-return valve

• Relief valve drain materials

• Connection fittings

• Pipework materials

• Safe tray components

Existing valves may be old, leaking, seized, non-compliant or unsuitable for the new system.

The correct valve setup depends on water pressure, temperature, system type, location and local compliance requirements.

Step 11: Decide Whether to Replace Like-for-Like or Upgrade

A like-for-like electric replacement is often the simplest path, but it is not always the best option.

Like-for-Like May Suit When

• The old system performed well

• The tank size was suitable

• The electrical supply is suitable

• The system location is staying the same

• Access is straightforward

• The existing setup is compliant

• You want a simple replacement

Upgrading May Suit When

• The old tank was too small

• The household has grown

• The system runs out of hot water

• You want better efficiency

• You have solar power

• You want to compare heat pumps

• The existing location is poor

• The electrical setup is being changed

A like-for-like product may reduce complexity, but a larger tank or heat pump may be worth comparing if the old setup no longer suits the household.

Electric Storage vs Heat Pump Replacement

When replacing electric hot water, many buyers compare standard electric storage with heat pump hot water.

A heat pump hot water system may be worth comparing where the site has suitable outdoor airflow, condensate drainage, noise placement and electrical setup.

Heat pump rebates, STCs and incentives can change and depend on the product, installer, property, purchase type and program rules. Do not assume a rebate applies without checking current eligibility.

When to Consider a Heat Pump Instead

A heat pump may suit when:

• The existing electric tank is old or expensive to run

• The home has solar power

• There is suitable outdoor airflow

• Drainage can be managed

• Noise placement is acceptable

• The household has regular hot water use

• Energy efficiency is a priority

• The electrical setup is suitable

A heat pump may not suit when:

• The unit would be inside a tight cupboard

• Outdoor airflow is restricted

• Drainage is difficult

• The unit would be too close to bedrooms

• Noise may affect neighbours

• Access is difficult

• The household has high peak demand and the system is not sized correctly

Brands commonly compared in the heat pump category include iStore hot water systems, Stiebel Eltron hot water systems, Envirosun hot water systems and Emerald Energy.

When to Consider Instant Electric

Instant electric hot water systems may suit selected applications, but they are not always suitable for whole-home hot water replacement.

Instant Electric May Suit

• Hand basins

• Kitchenettes

• Small studios

• Detached offices

• Single outlet applications

• Low-flow point-of-use hot water

Instant Electric May Not Suit

• Whole-home hot water

• Multiple bathrooms

• Back-to-back showers

• Large families

• High-flow shower use

• Homes with limited electrical capacity

• Sites where switchboard upgrades are not practical

Instant electric can require significant electrical capacity, so a licensed electrician should confirm suitability before purchase.

Common Electric Hot Water Replacement Sizes

50L Electric Hot Water Systems

A 50L electric hot water system may suit very small point-of-use applications, studios, single occupants or low-demand areas.

It may not suit homes with regular shower use by multiple people.

80L Electric Hot Water Systems

An 80L system may suit small units, single-person households or limited hot water demand.

It may run out quickly with long showers or back-to-back use.

125L Electric Hot Water Systems

A 125L system may suit one to two people, depending on shower habits and recovery setup.

It is commonly compared for apartments, townhouses and small homes.

160L Electric Hot Water Systems

A 160L system may suit two to three people, depending on usage. It may be a practical middle option where space is limited.

250L Electric Hot Water Systems

A 250L system is commonly compared for small families or homes with moderate use.

It may suit households where multiple showers are common but demand is not excessive.

315L Electric Hot Water Systems

A 315L system may suit larger families, homes with baths or properties where more stored hot water is needed.

The installation space, access and electrical setup need to be checked carefully.

Best Brands for Electric Hot Water Replacement

The best brand depends on tank size, budget, warranty conditions, available space and household demand.

Rheem

Rheem hot water systems are commonly compared for electric storage replacements across a wide range of sizes.

Dux

Dux hot water systems are often compared for practical electric storage replacements in homes, units, townhouses and rentals.

Vulcan

Vulcan hot water systems are often considered for budget-conscious electric storage replacements.

Stiebel Eltron

Stiebel Eltron hot water systems may suit buyers comparing electric storage, instant electric and heat pump options.

iStore, Envirosun and Emerald Energy

iStore, Envirosun and Emerald Energy are commonly compared when buyers are considering a heat pump instead of standard electric storage.

Common Mistakes When Replacing Electric Hot Water

Buying the Same Litres Without Checking Usage

If the old system ran out of hot water, buying the same size may repeat the same problem.

Not Checking Dimensions

The same litre size can have different height, width and connection locations.

Ignoring Element Rating

A different element rating may need different electrical requirements.

Forgetting About Off-Peak Supply

If the system only heats during certain periods, tank size and recovery time matter.

Choosing Heat Pump Without Checking Airflow

Heat pumps need airflow, drainage and sensible noise placement.

Buying Instant Electric Without Checking Power

Instant electric may require significant electrical capacity and is not always suitable for whole-home hot water.

Forgetting Valves and Fittings

The replacement may require new valves, fittings and compliance parts.

Ignoring Drainage

Relief valve discharge and indoor safe tray drainage must be managed correctly.

Comparing Supply-Only Price to Installed Cost

Supply-only pricing does not include installation, electrical work, plumbing labour, valves, fittings, old unit removal, disposal or compliance upgrades.

Not Checking Access

Large tanks can be difficult to move through stairs, tight side paths, apartments or cupboards.

Buyer Checklist Before Ordering Online

Before ordering a supply-only electric hot water replacement, confirm:

• Existing brand and model

• Existing tank size

• Existing element rating

• Number of people in the home

• Number of bathrooms

• Whether showers run at the same time

• Whether the home has a bath

• Whether the old tank size was enough

• Indoor or outdoor location

• Existing unit dimensions

• New unit dimensions

• Doorway and access path

• Electrical circuit requirements

• Switchboard capacity

• Off-peak or controlled-load setup

• Timer setup if applicable

• Drainage and discharge point

• Safe tray requirements

• Valve and fitting requirements

• Whether heat pump is being considered

• Whether instant electric is suitable

• Licensed plumbing and electrical requirements

Supply-Only vs Installed Cost

Hot Water Outlet sells supply-only hot water systems and accessories online. Supply-only pricing is useful for comparing product costs, but it is not the same as total installed cost.

Supply-only pricing usually does not include:

• Installation

• Plumbing labour

• Electrical work

• Old unit removal

• Disposal

• Valves

• Fittings

• Pipework changes

• Drainage work

• Switchboard upgrades

• Electrical circuit upgrades

• Timer changes

• Compliance upgrades

• Concrete bases or platforms

• Delivery beyond what is shown at checkout

Where appropriate, Hot Water Outlet may help organise quotes from reputable installers.

FAQ: Electric Hot Water System Replacement Guide

What should I check before replacing an electric hot water system?

Check the existing tank size, element rating, dimensions, installation location, electrical circuit, access, drainage, valves, fittings and household hot water demand.

Can I replace an electric hot water system with the same size?

Yes, if the old size suited the household and the new unit fits the space. However, if the old system ran out of hot water or the household has changed, a different size may be needed.

Can I replace electric storage with a heat pump?

Yes, if the property has suitable outdoor airflow, drainage, noise placement, electrical supply and enough space. A heat pump may be worth comparing for energy-conscious homes.

Is instant electric a good replacement for electric storage?

Instant electric may suit small point-of-use applications, but it is not always suitable for whole-home hot water because it can require significant electrical capacity.

Do I need an electrician to replace an electric hot water system?

Electrical work must be completed by a licensed electrician. Even like-for-like replacements may need electrical checks, isolation or compliance work.

Do I need new valves when replacing electric hot water?

Often, yes. The required valves depend on water pressure, temperature, system type, location and compliance requirements. A licensed plumber should confirm what is needed.

What size electric hot water system do I need for a family of four?

A family of four often compares 250L to 315L electric storage, depending on shower habits, baths, bathrooms and tariff setup.

Can I put an electric hot water system inside a cupboard?

Only if the unit is suitable for the location and the setup meets drainage, access, safe tray and compliance requirements. Always check product suitability and licensed trade advice.

Does supply-only pricing include installation?

No. Supply-only pricing generally does not include installation, plumbing labour, electrical work, valves, fittings, pipework changes, old unit removal, disposal or compliance upgrades.

Can Hot Water Outlet install the system?

Hot Water Outlet sells supply-only hot water systems and accessories online. Plumbing and electrical work must be completed by appropriately licensed tradespeople. Where appropriate, Hot Water Outlet may help organise quotes from reputable installers.

Final Thoughts

Replacing an electric hot water system starts with checking the existing tank size, element rating, dimensions, electrical supply, drainage, valves and access. A like-for-like electric replacement may be the simplest option, but a heat pump may be worth comparing if you want an efficient electric upgrade and the site suits.

Browse electric hot water systems, compare heat pump hot water systems, instant electric hot water systems and compatible valves, pipework and fittings online at Hot Water Outlet.