Continuous flow and instantaneous hot water on the Mornington Peninsula

Updated October 2026

Continuous flow hot water, also called instantaneous hot water, is the system that never runs out. There is no tank. A compact wall-mounted unit heats water on demand as it flows through, so the last shower after a day at the beach is as hot as the first. Mornington Hot Water connects you with licensed plumbers and gasfitters across the Mornington Peninsula who install, replace and repair continuous flow systems from the major brands.

We are a referral service, not a plumbing business. The licensed hot water plumbers we work with handle the plumbing, with gasfitting-endorsed plumbers on gas units and licensed electricians on hard-wired electric units, as Victoria requires.

How continuous flow works

When you open a hot tap, the unit senses the flow and fires a gas burner (or, less commonly, electric elements) around a heat exchanger. Water heats as it passes through and stops heating the moment you close the tap. No tank means no stored water cooling overnight, no standing heat loss, and no cylinder to corrode and flood the laundry. Many units support bathroom controllers that let you set an exact temperature.

Why it suits Peninsula households

Endless hot water. Sized correctly, it keeps up with back-to-back showers, a bath and the dishwasher, plus the sandy kids and wetsuits after a day at the back beach.
Holiday houses. No tank keeping water hot for an empty building, and nothing corroding quietly between visits. For a house used a few weeks a year, that is a genuine advantage over storage.
Space. The unit is about the size of a small suitcase on an external wall. For narrow side paths at Rye and Rosebud, and townhouse courtyards in Mornington, that matters.
Lifespan. With no tank to corrode, continuous flow units commonly last 15 to 20 years with occasional servicing, versus 8 to 12 for a storage tank.
Efficiency. You only heat the water you use. For gas households, running costs are typically lower than gas storage.

The trade-off is that gas units need adequate gas supply. Older or undersized gas lines sometimes need upgrading to feed a large unit, and mains gas does not reach the whole Peninsula, so the plumber checks your meter and line before quoting. Homes without mains gas can run continuous flow on LPG, though bottle costs raise the running cost and a bottle that empties mid-stay is its own kind of problem. The gas hot water page covers supply in more detail.

Sizing: litres per minute, not litres

Continuous flow units are rated by flow, not capacity. As a guide, a 20L/min unit suits most two-bathroom homes, while 26L/min suits larger households likely to run two showers and a tap at once. Multi-level homes on steep blocks at Mount Martha, Mount Eliza or Arthurs Seat, with a long run to the top bathroom, are worth sizing carefully. Holiday houses that sleep twelve over summer should be sized for the crowd, not the couple. Undersizing is the common mistake: the unit still works, but flow drops when several outlets run.

Repair or replace

Continuous flow units display error codes when something fails, which makes diagnosis quicker. Igniters, sensors, valves and fans are all repairable, and on a unit under ten years old, repair is usually the right call. If the heat exchanger has failed on an older unit, replacement normally makes more sense. Swapping an old unit for a new one on the same wall is one of the quickest hot water jobs there is, often done in a couple of hours.

Coastal placement matters here too. Units on walls facing the water wear faster in salt air, so position and servicing intervals deserve attention near the beach.

Cost and licensing

Installed pricing varies with unit size, flueing and whether the gas line needs upgrading, with gas systems as a category typically running about $1,200 to $3,500 installed. A like-for-like continuous flow swap sits comfortably inside that range, while converting from a storage tank costs more because pipework and gas supply change.

In Victoria, plumbing must be done by a licensed or registered plumber and gas connections by a plumber with the relevant gasfitting endorsement. Hard-wired electric continuous flow units need a licensed electrician. For plumbing work valued over $750 you receive a compliance certificate. Every tradesperson we refer holds the licences their part of the job requires.

Get a fast quote for continuous flow hot water from a licensed local plumber.

Frequently asked questions

Is continuous flow hot water really instant?

The unit heats instantly, but hot water still has to travel from the unit to your tap, so there is a short delay, the same as with a tank. Mounting the unit close to the main bathroom cuts the wait.

What size continuous flow unit do I need?

For most two-bathroom homes, 20L/min. For larger households running multiple showers at once, 26L/min. Smaller 16L/min units suit one-bathroom homes and units. The plumber sizes it from your bathroom count and usage.

Is continuous flow a good idea for a holiday house?

Often yes. There is no tank sitting hot and corroding while the house is empty, and the system copes with a sudden full house. On an LPG property, keep an eye on bottle levels before a busy stay.

My continuous flow unit is showing an error code. What do I do?

Note the code, turn the unit off and on at the isolation switch, and if the code returns, book a plumber. Codes map to specific faults, so the plumber often arrives knowing which part is likely needed.