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Heat Pump Hot Water Replacement in Toorak — Older Home Case Study
Heat Pump Hot Water Replacement in Toorak — Older Home Case Study — a Prime Plumbing & Gasfitting plain-English guide to heat pump replacement toorak for Melbourne homeowners. Below we cover what works, what doesn't, and when to call a licensed plumber.
Quick answer: We recently completed a heat pump replacement Toorak job — replacing a 16-year-old gas storage hot water unit on a 1920s older home with a modern heat pump. The owners were after the Solar Victoria rebate and the lower long-term running cost. This case study walks through the diagnostic process, what we found in the side passage where the old unit sat, how we routed the new electrical and plumbing for the heat pump's slightly different inlet position, and what the compliance work looked like at the end. Half-day job, written fixed-price quote up front, Certificate of Compliance issued same day.
What we found at the older home
The home is a 1920s Toorak weatherboard with a narrow side passage between the house and the boundary fence. The original gas storage hot water unit had been tucked into that space for the past 16 years — common positioning for heat pump replacement toorak customers in older homes.
The diagnostic showed:
- Element corrosion that had been gradually reducing output over the past 6-12 months — the owners had been getting intermittent hot water for weeks before the unit failed outright
- A sacrificial anode that had never been replaced in the unit's working life. Most homeowners don't know that gas storage units need anode replacement every 5-7 years to prevent the tank from corroding from the inside
- Gas line still serviceable with a working isolation valve at the meter — no gas-side replacement needed
- Outdoor location with reasonable airflow and partial shade from the neighbouring fence
The unit was 200 L capacity. Family of four. Hot water demand: morning showers and evening dishwasher.
How a heat pump replacement Toorak install actually goes
Once the owners signed off the written fixed-price quote, the work itself ran like this:
1. Decommissioning the old gas unit
Gas isolated at the meter, water lines drained and capped, old unit removed and taken to scrap. The plumber kept the gas isolation valve in place for potential future use (the gas line stays operational at the meter, the unit-side fittings are just capped).
2. Re-routing for the heat pump's inlet position
A heat pump compressor sits in a slightly different position to a gas storage unit, with the inlet on the opposite side. We re-routed the cold-water supply line about 600mm to match. Clean copper, neat fittings.
3. New electrical circuit
Heat pumps draw around 10A continuously when the compressor is heating water. Many older Toorak homes have older switchboards that need a dedicated circuit run for the new unit. We coordinated this with a licensed electrician (the actual electrical wiring is their scope, not ours).
4. Heat pump installation
The compressor went outdoors in roughly the same position as the old unit. We chose the spot for airflow (heat pumps need ambient air movement to work efficiently) but kept it under the eave for weather protection. Noise consideration too — Toorak boundary fences are often close to neighbouring living areas, and modern heat pumps are quieter than older units but still audible.
5. Compliance
Certificate of Compliance issued for the plumbing portion, emailed PDF same day. The heat pump installation also generates Victorian Energy Upgrades certificates which we processed on the customer's behalf — that's part of how the Solar Victoria rebate paperwork works.
Total time on site: about half a day. Hot water back on by mid-afternoon.
Why a heat pump replacement Toorak made financial sense here
The owners had originally planned a like-for-like gas replacement. We costed both options in the written quote — gas-to-gas would have been cheaper up front by several hundred dollars, but the heat pump's running cost is significantly lower over its 12-15 year expected life. Plus:
- Solar Victoria heat pump rebate brought the install gap close to the cost of like-for-like gas
- Lower ongoing electricity use vs gas (heat pumps are typically 3-4× more efficient than electric storage and significantly cheaper to run than gas in 2026 prices)
- No combustion emissions — the owners were progressively phasing out gas appliances
- Quieter outdoor unit vs the older gas storage which had a noisy ignition cycle
The heat pump replacement Toorak decision matrix usually comes down to: how long are you planning to stay in the property, what's your daily hot water demand, and what's your appetite for upfront vs ongoing cost. For this household, the math supported the heat pump.
Heat pump replacement Toorak — booking checklist
Quick checklist to share with the plumber when you book a heat pump replacement Toorak job:
- What's the current hot water unit (gas storage / electric storage / continuous flow)?
- Where is it located (indoor / outdoor / side passage / under house)?
- Daily hot water demand (single, couple, family-of-4, family-of-6)?
- Any access constraints (narrow passage, gate width, garden plantings)?
- Current switchboard age and amperage available?
When to call a licensed plumber for a heat pump replacement
A heat pump replacement toorak job needs a licensed plumber if any of these apply:
Prime Plumbing & Gasfitting is BPC #103414 licensed and Type A Gasfitter registered with Energy Safe Victoria. All heat pump replacement Toorak jobs come with a written quote sent before the booking is confirmed, and a Certificate of Compliance at completion.
Frequently asked questions
Yes. Heat pumps are rated for ambient temperatures well below Melbourne's winter lows. Efficiency does drop slightly in cold weather but the unit still produces hot water faster and cheaper than electric storage at typical Melbourne winter temperatures. The compressor runs more frequently in winter — the trade-off is built into the design.
Roughly the same as a gas replacement — half to full day, depending on access and electrical work required. The main difference is the electrical circuit (if a new one is needed) and sometimes the position of the outdoor compressor.
The rebate is processed as part of the install — Prime Plumbing & Gasfitting submits the Victorian Energy Upgrades paperwork on your behalf. You don't need to apply separately, and the rebate comes off the install cost rather than being paid as a separate payment afterwards.
In most cases yes — the old unit stays connected and operational until the heat pump install day. The change-over happens during the install (typically 4-6 hours without hot water during the day).
For most older Toorak homes with side-passage gas storage units, yes. The compressor unit is similar in size, sometimes slightly smaller. We measure during the quote visit and confirm before booking.
Before You Book
A quick checklist to share with your plumber when you book:
- When did the issue start?
- Is it isolated to one fixture or multiple areas?
- Are there any visible leaks, smells or unusual sounds?
- Have you turned off the relevant isolation valve?
- Hot water system installations and repairs — full hot water service page
- Older plumbing in Toorak — Toorak suburb landing page with full service list
- Heat pump vs gas hot water comparison — decision guide
- Gas fitting services — gas decommissioning, certification
For a heat pump replacement Toorak quote, phone Prime Plumbing & Gasfitting on 0475 407 670 or send an enquiry. BPC #103414. Fixed-price quotes before any work begins.
