Heat Pump Hot Water Replacement Guide

Replacing a heat pump hot water system is not the same as replacing a standard electric tank. A heat pump needs the right tank size, airflow, drainage, noise placement, electrical supply, access and compliant plumbing setup. Before buying online, check whether you are replacing an existing heat pump like-for-like or changing from electric, gas or solar hot water to heat pump. At Hot Water Outlet, you can compare supply-only hot water systems online, including heat pump hot water systems, electric hot water systems, gas hot water systems, instant gas hot water systems and compatible valves, pipework and fittings.

Quick Answer

Before replacing a heat pump hot water system, check:

• Existing heat pump size

• Tank capacity

• Electrical supply

• Outdoor airflow

• Condensate drainage

• Noise placement

• Access for delivery

• Existing valves and fittings

• Existing base or slab

• Pipework connection points

• Household hot water demand

• Whether rebates, STCs or incentives apply

• Licensed plumbing and electrical requirements

A like-for-like heat pump hot water system may be suitable when the existing setup has worked well, the location has good airflow and the household demand has not changed.

If the old heat pump was noisy, slow to recover, poorly located or undersized, the replacement should not be chosen by tank size alone.

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

Heat Pump Replacement Checklist

Step 1: Identify the Existing Heat Pump

Start by checking the existing system details.

Look for:

• Brand

• Model

• Tank size

• Serial plate

• Electrical rating

• Approximate age

• Current location

• Air inlet and outlet position

• Condensate drain location

• Relief valve drain location

• Pipework connection points

• Existing valve setup

If the existing heat pump worked well, a similar replacement may be a practical starting point. If it regularly ran out of hot water, made too much noise, produced drainage issues or was installed in a poor location, the replacement needs more careful review.

Step 2: Check the Tank Size

Heat pump hot water systems still store hot water in a tank, so tank size matters.

Common sizes may include:

Do not choose a heat pump only by copying the old size. If the household has changed or the old system was not keeping up, a different size may be needed.

Step 3: Check the Existing Location

Heat pump placement is one of the most important checks.

A heat pump needs access to air. It should not be treated like a normal electric storage tank that can simply be placed anywhere.

Check:

• Outdoor location

• Airflow around the unit

• Clearance to walls and fences

• Distance to bedrooms

• Distance to neighbours

• Distance to windows and doors

• Whether the area is enclosed

• Whether hot or cold discharge air could be a nuisance

• Whether the location allows future servicing

• Whether the unit can be delivered safely

A heat pump in a tight cupboard, enclosed corner or poorly ventilated space may not be suitable.

Step 4: Check Airflow

Heat pumps work by extracting heat from the surrounding air. If airflow is restricted, performance and recovery may be affected.

Before ordering, check:

• Minimum clearance requirements for the model

• Air inlet position

• Air outlet position

• Whether the unit is against a wall

• Whether fencing blocks airflow

• Whether the system is in a narrow side passage

• Whether vegetation blocks airflow

• Whether the location is enclosed

• Whether the manufacturer allows the proposed location

Different heat pump models can have different clearance requirements. Always check the product information before buying.

Step 5: Check Noise Placement

Heat pumps make operational noise. The level and type of noise can vary by model, location and operating conditions.

Before replacing a heat pump, check whether the system location is near:

• Bedrooms

• Neighbouring bedrooms

• Living areas

• Courtyards

• Units or townhouses

• Boundary fences

• Echo-prone walls

• Narrow side paths

• Outdoor entertaining areas

If the old heat pump caused noise complaints, do not simply replace it in the same location without checking whether a different position or model would be better.

Step 6: Check Condensate Drainage

Heat pumps produce condensate as part of normal operation. This water needs to drain safely.

Check:

• Existing condensate drain

• Whether condensate currently pools on the ground

• Whether the drain is blocked

• Whether discharge causes slippery areas

• Whether the replacement unit has a different condensate outlet

• Whether drainage needs to be altered

• Whether the location has a suitable drain point

Poor condensate drainage can cause nuisance water, slippery surfaces, staining or damage.

Step 7: Check Relief Valve Drainage

Like other storage hot water systems, heat pumps have valves that may discharge water.

Check:

• Relief valve drain location

• Safe discharge point

• Drainage pipe condition

• Whether discharge could damage walls, paths or foundations

• Whether the replacement valve position changes

• Whether pipework needs alteration

Drainage should be checked as part of the replacement, especially if the old system has signs of leaking, dripping or poor discharge control.

Step 8: Check the Electrical Supply

Heat pump hot water systems use electricity and need a suitable circuit.

Electrical checks may include:

• Existing circuit size

• Isolator location

• Switchboard capacity

• Circuit protection

• Timer or control setup

• Boost element requirements

• Whether the existing circuit is suitable for the replacement model

• Whether the system is connected to controlled load or standard supply

• Whether solar timer operation is planned

Electrical work must be completed by a licensed electrician.

Do not assume every heat pump has the same electrical requirements. Different models may require different setup details.

Step 9: Check Solar Power and Timer Setup

Many buyers compare heat pumps because they have solar power or want an efficient electric hot water option.

If the property has solar power, check:

• Solar system size

• Daytime production

• Household usage pattern

• Timer options

• Heat pump operating window

• Boost element operation

• Electrical tariff

• Controlled load setup

• Whether the system can be timed to suit solar production

• Whether the household uses most hot water morning or evening

Solar power does not automatically make every heat pump setup ideal. The system still needs to match the household and electrical arrangement.

Step 10: Check the Existing Base or Slab

Heat pumps are usually heavier and larger than small electric storage systems.

Before ordering, check:

• Existing slab size

• Whether the base is level

• Whether the base is stable

• Whether the new unit footprint fits

• Whether drainage is affected

• Whether the unit needs to be raised

• Whether the location floods

• Whether the base allows service access

Supply-only pricing usually does not include concrete bases, platforms or site preparation unless specifically shown at checkout or quoted separately.

Step 11: Check Access for Delivery and Replacement

Heat pumps can be heavy and bulky. Access matters.

Check:

• Driveway access

• Side access

• Gate width

• Stairs

• Retaining walls

• Steep blocks

• Narrow pathways

• Tight corners

• Distance from delivery point to installation location

• Whether old unit removal is difficult

• Whether specialist lifting may be needed

A heat pump may be suitable for the home but difficult to move into place. Access should be checked before purchase.

Step 12: Check Valves and Fittings

Heat pump replacement often requires more than the system 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

• Condensate drainage materials

• Connection fittings

• Pipework materials

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

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

Step 13: Check Warranty Conditions

Warranty varies by brand, model, component and installation conditions.

Before buying, check:

• Tank warranty

• Compressor warranty

• Parts warranty

• Labour warranty, if any

• Installation requirements

• Location requirements

• Water quality requirements

• Service access requirements

• Maintenance requirements

• Proof of purchase requirements

• Licensed installation requirements

Do not assume every part of the heat pump has the same warranty period. Tank, compressor, controller, sensors, valves and labour may be covered differently.

Step 14: Check Rebates, STCs and Incentives

Heat pump hot water systems may be eligible for rebates, STCs or incentives, but eligibility can change.

Eligibility may depend on:

• Product model

• Installer

• Property type

• Existing system type

• State or territory

• Purchase type

• Installation date

• Program rules

• Whether the buyer or installer claims the incentive

Do not assume a rebate applies just because the system is a heat pump. Always check current eligibility before buying.

Replacing Heat Pump With Heat Pump

Replacing an old heat pump with a new heat pump may be straightforward if the existing location, drainage and electrical setup are suitable.

A like-for-like replacement may suit when:

• The existing heat pump location works well

• Airflow is suitable

• Noise has not been an issue

• Drainage is already correct

• The tank size suited the household

• Electrical supply is suitable

• Access is reasonable

• The buyer wants to stay with efficient electric hot water

However, a new heat pump may have different dimensions, airflow requirements, electrical requirements and connection positions. Always check the model details before ordering.

Replacing Electric Storage With Heat Pump

Replacing electric storage with a heat pump hot water system is common for buyers wanting an efficient electric upgrade.

This may suit when:

• The old electric tank is due for replacement

• The home has suitable outdoor space

• The household has regular hot water use

• The home has solar power

• Energy efficiency is a priority

• Noise placement can be managed

• Condensate drainage can be provided

• Electrical supply is suitable

It may not suit when:

• The electric tank is inside a cupboard

• No outdoor location is available

• Airflow is poor

• Drainage is difficult

• Noise may affect bedrooms or neighbours

• Access is too difficult

• The household has high peak demand and the heat pump is undersized

If heat pump placement does not suit, a like-for-like electric hot water system may be more practical.

Replacing Gas With Heat Pump

A heat pump may suit homes moving away from gas.

This may be worth comparing when:

• The home has solar power

• LPG bottle supply is inconvenient

• Natural gas hot water is being removed

• The property is moving toward all-electric appliances

• The old gas system is due for replacement

• There is suitable outdoor airflow

• Electrical supply is suitable

Changing from gas to heat pump is not a direct swap. It may require:

• Gas disconnection or capping

• Plumbing changes

• Electrical circuit work

• Drainage changes

• New base or slab

• Valve and fitting changes

• Old gas unit removal

Gas fitting, plumbing and electrical work must be completed by appropriately licensed tradespeople.

Replacing Solar Hot Water With Heat Pump

A heat pump is often compared when replacing old solar hot water.

This may suit when:

• The old solar tank has failed

• Roof collectors are leaking or damaged

• The buyer wants to remove roof-mounted hot water equipment

• The home has solar PV power

• The site has suitable airflow and drainage

• The electrical supply is suitable

• A modern electric replacement is preferred

Solar hot water replacement may also involve:

• Roof collector removal

• Roof tank removal

• Solar pipework isolation

• Crane or specialist lifting

• Roof repairs

• Electrical or gas booster disconnection

• Disposal

Supply-only pricing does not include roof work, crane work, old solar component removal or specialist lifting unless specifically shown or quoted.

Heat Pump vs Electric Storage Replacement

Many buyers compare heat pump and electric storage when replacing hot water.

A heat pump may be better where the site suits and energy efficiency matters. Electric storage may be better where simplicity, lower product cost or location flexibility matters more.

What Size Heat Pump Do You Need?

Heat pump sizing should consider household demand, not just the old tank size.

If the old heat pump ran out of hot water, replacing it with the same size may not solve the problem.

Best Heat Pump Brands to Compare

The best heat pump brand depends on household size, site conditions, budget, warranty conditions and model availability.

iStore

iStore hot water systems are commonly compared for heat pump replacements, especially where buyers are moving away from standard electric storage or gas hot water.

Stiebel Eltron

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

Envirosun

Envirosun hot water systems are commonly compared in the heat pump category for homes with suitable outdoor space.

Emerald Energy

Emerald Energy is often compared by buyers looking at heat pump value options.

Rheem

Rheem hot water systems are commonly compared across heat pump, electric, gas and instant gas categories.

Dux

Dux hot water systems may be compared where buyers are considering electric storage or alternative replacement options alongside heat pump.

Common Mistakes When Replacing Heat Pump Hot Water

Choosing by Tank Size Only

Tank size matters, but airflow, recovery, household demand and operating conditions also matter.

Ignoring Airflow

A heat pump needs suitable air movement. Restricted airflow can cause performance problems.

Forgetting About Noise

Heat pump noise can matter near bedrooms, neighbours and narrow side passages.

Not Checking Condensate Drainage

Heat pumps produce condensate that needs to drain safely.

Assuming All Heat Pumps Fit the Same Space

Different models can have different heights, widths, connection points and clearance requirements.

Reusing Old Valves Without Checking

Old valves may be leaking, seized, non-compliant or unsuitable.

Ignoring Electrical Requirements

The replacement model may have different electrical requirements from the old system.

Assuming Rebates Always Apply

Rebates, STCs and incentives can change and depend on the product, installer, property, purchase type and program rules.

Comparing Supply-Only Price to Installed Cost

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

Replacing Gas or Solar With Heat Pump Without Checking Extra Work

Changing from gas or solar to heat pump can involve gas fitting, electrical work, roof work, pipework changes and drainage changes.

Buyer Checklist Before Ordering Online

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

• Existing system type

• Existing tank size

• Existing heat pump brand and model

• 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 heat pump size was enough

• Outdoor airflow

• Clearance around the unit

• Noise placement

• Condensate drainage

• Relief valve drainage

• Electrical supply

• Switchboard capacity

• Timer or solar setup

• Existing base or slab

• New unit dimensions

• Access for delivery and replacement

• Required valves and fittings

• Warranty conditions

• Rebate or STC eligibility

• Licensed plumbing and electrical requirements

• Gas or solar disconnection requirements if changing from another system type

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

• Condensate drainage changes

• Switchboard upgrades

• Electrical circuit upgrades

• Gas disconnection

• Solar pipework isolation

• Roof collector removal

• 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: Heat Pump Hot Water Replacement Guide

What should I check before replacing a heat pump hot water system?

Check the existing tank size, model, airflow, drainage, noise placement, electrical supply, access, base, valves, fittings, warranty conditions and household hot water demand.

Can I replace a heat pump with another heat pump?

Yes, if the existing location, airflow, drainage and electrical setup are suitable. However, the new model may have different dimensions, clearance requirements and connection points.

Can I replace electric storage with a heat pump?

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

Can I replace gas hot water with a heat pump?

Yes, but it is not a direct swap. Gas disconnection, plumbing changes, electrical work, drainage and valve changes may be required.

Can I replace solar hot water with a heat pump?

Yes, a heat pump may be a practical replacement for old solar hot water, but solar collector removal, roof work, pipework isolation or booster disconnection may also need to be considered.

Do heat pumps need drainage?

Yes. Heat pumps need drainage for condensate, and storage systems also need safe relief valve discharge.

Are heat pumps noisy?

Heat pumps make operational noise. Placement should be checked carefully, especially near bedrooms, neighbours, townhouses and narrow side access areas.

Are heat pump rebates always available?

No. Rebates, STCs and incentives can change and depend on product, installer, property, purchase type and program rules. Always check current eligibility before buying.

Does supply-only pricing include installation?

No. Supply-only pricing generally does not include installation, plumbing labour, electrical work, valves, fittings, drainage 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 a heat pump hot water system starts with checking more than just tank size. Airflow, drainage, noise, electrical supply, access, valves, fittings and household demand all matter.

A like-for-like heat pump replacement may suit where the old setup worked well. If you are replacing electric, gas or solar hot water with a heat pump, allow for extra checks and licensed trade work.

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