Choosing a Hot Water System for a Period Home
How to choose a hot water system for a large inner-east period home: sizing for the household, system types, honest trade-offs, siting and heritage.
By the Toorak Plumbers teamPublished 12 July 2026
Start with the household, not the brand
Large period homes across Toorak, Armadale and Malvern often have several bathrooms, an ensuite or two and a busy kitchen that all want hot water at the same time. When a household tells us its hot water “runs out”, the cause is usually not a faulty unit; it is a system that was never sized for genuine simultaneous demand. Before we compare brands, we work out how many outlets can realistically run together on a weekday morning and size the system from there.
Sizing is about both capacity and recovery. A storage system needs a tank big enough for the peak and a heat source that reheats it quickly enough for the next person, while a continuous flow system needs enough flow rate to feed two or more showers without going lukewarm. Getting this right at the start is far cheaper than discovering the shortfall after a unit is already on the wall.
The system types, and their honest trade-offs
There is no single best system, only the one that suits your home, your fuel and how you use hot water. In plain terms, here is how the common options compare.
- Gas storage keeps a tank of hot water ready and refills it steadily. It is simple and well suited to homes with mains gas, though the tank takes floor space and standing heat loss adds a little to running cost.
- Gas continuous flow (instantaneous) heats water on demand with no tank, so it does not run out and it saves space, which helps in a tight courtyard. It relies on a good gas supply and adequate flow, and very heavy simultaneous demand can still stretch a single unit.
- Electric storage is the simplest option and easy to site indoors, but running cost on peak electricity is usually the highest of the group unless it is paired with a controlled off-peak tariff.
- Heat pumps draw heat from the air and are the most efficient electric choice, which suits the shift away from gas. They need outdoor space with airflow, add some fan noise, cost more up front and can recover more slowly in cold weather.
- Solar with gas or electric boost uses roof collectors plus a booster for dull days. Running cost over time is low, but it needs suitable roof space and orientation and carries the highest up-front outlay.
Check what your home can actually supply
Most established inner-east homes have mains gas, but we do not assume it. We confirm the gas connection and its capacity before recommending a gas unit, because a large continuous flow system in particular needs a supply that can feed it at full rate.
If you are moving away from gas, or the home never had it, a heat pump or electric system is the direction, and there the question becomes electrical capacity: the switchboard, the circuit and, for a heat pump, a sensible outdoor position. We check these early so the quote reflects the real work rather than a best case.
Siting, space and heritage
Where the unit lives matters as much as what it is, and in the inner east there are a few local realities worth planning for before anything is ordered.
- Clearances and compliance: every unit has minimum clearances from windows, boundaries and openings. A spot that looks convenient can fail the rules, so we confirm it before committing.
- Heritage overlays: much of Toorak and the surrounding streets sit under heritage controls, so an external unit visible from the street can need council consideration. A position out of public view is worth planning from the start.
- Tight courtyards and terraces: where space is limited, a continuous flow unit or a slimmer tank often fits where a bulky storage cylinder will not.
- Noise and neighbours: heat pumps run a fan, so we site them away from bedroom windows, both yours and next door’s.
Retrofitting into an older home
Period homes rarely offer a blank slate. Existing pipe runs, an old flue, the switchboard and the space the previous unit occupied all shape what will fit without major rework. Part of a sound quote is working out how a new unit meets the plumbing already in the walls.
Sometimes the sensible answer is a like-for-like changeover, a modern version of what you already have, sited where the plumbing already suits it. Other times the retrofit is the moment to change fuel or type. Either way we set out the options, quote a fixed price before we start, and give straight advice on repair versus replace for homes across Toorak, Armadale, Malvern, Prahran, South Yarra and Kooyong.
In Victoria, installing or replacing a hot water system is licensed plumbing work, and gas and electrical connections carry their own certification, so this is a job for a licensed plumber, and a registered gas-fitter where gas is involved, from the outset.
Common questions
How do I know if my hot water system is too small?
The clearest sign is hot water running short when several outlets are used together, such as a shower going cold when the dishwasher or a second shower runs. That usually points to under-sizing rather than a fault. When we quote a replacement we size for your household’s peak demand so it does not keep happening.
Can I switch from gas to a heat pump in an older home?
Often yes. The main things we check are outdoor space with airflow for the unit and whether your switchboard and wiring can support it. Period homes sometimes need electrical upgrades to suit, which we identify before quoting so there are no surprises later.
Will a new hot water unit need council consideration under a heritage overlay?
A like-for-like replacement in the same position is usually straightforward. Consideration is more likely when a new or relocated unit would be visible from the street in a heritage area, which is common in Toorak. We plan the siting with that in mind and will tell you if it is a factor for your property.