Electric instantaneous hot water can suit a home with limited installation space and a compatible electrical supply. Before buying, check that the selected heater can deliver enough hot water for the outlets you use together. Many larger models require three-phase power; compact single-phase units are generally intended for smaller demands such as a basin or sink.
For Blacktown homeowners, a useful starting point is deciding whether you need hot water for one outlet or across the whole property. You can then browse electric instantaneous hot water systems with those requirements in mind.
Single-phase and three-phase systems serve different needs
Having an electricity connection does not mean every electric water heater will work at your property.
STIEBEL ELTRON describes its single-phase instantaneous range as point-of-use heaters for smaller demands, including sinks and basins. Do not assume a compact single-phase unit will supply your bathroom or several outlets adequately.
Higher-output models often use three-phase power. An electrician must check the available supply and circuit capacity against the selected model’s requirements. Even an existing three-phase connection needs assessment before a replacement is selected.
For example, Blacktown Hot Water lists the STIEBEL ELTRON DEL 13 in its electric instantaneous range. Confirm its suitability for your planned outlets with the installer rather than selecting it solely because it fits the available space.

Choose by flow rate and temperature rise
Storage heaters are commonly compared by tank capacity. An instantaneous heater needs a different assessment: how much water it can heat as that water flows through the unit.
Tell your installer which outlets may operate together. Two showers at once present a different demand from one shower followed by kitchen use. Incoming water temperature also matters because colder water requires a greater temperature rise.
The manufacturer’s DEL Plus technical information explains that sizing depends on the outlets supplied and incoming cold water temperature. Ask for a recommendation based on your actual use, including winter conditions.
Compare the full installation cost
Ask for a written quote covering the heater, plumbing and electrical work. If you are changing system types, ask whether the existing circuit can be reused and whether any supply upgrade is necessary.
Useful questions include:
- Which exact model is recommended, and why?
- Will it support the outlets we use simultaneously?
- Does the quote include electrical alterations and removal of the old heater?
- Are any additional works subject to inspection?
This makes it easier to compare proposals that initially look similar.
Compare running costs with other electric options
An instantaneous heater heats water on demand and avoids storage-tank heat losses. That does not automatically make it the cheapest option to run. It must operate when hot water is used, so tariff arrangements matter.
The Australian Government’s Your Home hot water guide explains these trade-offs and the high electrical demand of larger instantaneous systems. If you are replacing a whole-home heater, compare electric storage systems and heat pump systems as part of the decision.
Questions to ask before ordering
Can I replace an electric storage tank with an instantaneous heater?
It may be possible, but the new heater’s electrical requirements must be assessed first. Request a quote for the complete changeover before purchasing.
Can one unit supply two bathrooms?
Some higher-output models can serve multiple outlets. Ask the installer to assess simultaneous shower use and incoming water temperature against the manufacturer’s sizing guidance.
Does three-phase power guarantee suitability?
No. Available current, circuit capacity and the heater’s output still need to match your property and household demand.
Find a suitable system for your Blacktown home
Before ordering, gather your existing heater’s model details, the number of bathrooms and a description of your busiest hot water period. These details help the team assess your options.
Contact Blacktown Hot Water or call (02) 9627 5447 to discuss supply and installation in Blacktown, Mount Druitt, Seven Hills and Western Sydney.