Hot water provision is a consistent pressure point in residential property markets worldwide. Buyers and tenants at the mid-market and above expect reliable hot water as a baseline — not as a premium feature. They check for it during viewings by running taps and asking about the hot water system. They ask what happens during power outages if the system is electrically dependent. They assess whether the system can serve multiple users simultaneously without pressure or temperature problems. A property that cannot credibly answer these questions loses negotiating strength and fails viewings with exactly the buyers and tenants who are most desirable.
Tankless water heaters — also called instant water heaters, on-demand heaters, or continuous-flow heaters — are one approach to providing reliable hot water in residential properties. This guide examines their role in property improvement honestly and completely: the genuine advantages, the real limitations, when they are the right choice, and when alternative hot water solutions are more appropriate.
What Tankless Water Heaters Are and How They Work
A tankless water heater heats water on demand as it flows through the unit, rather than maintaining a stored volume of pre-heated water. When a hot tap is opened, cold water enters the heater, passes through a heat exchanger that rapidly elevates its temperature, and is delivered to the outlet at the specified temperature. When the tap is closed and flow stops, the heating element switches off. There is no stored volume of hot water to maintain, no tank to descale or replace, and no standby heat loss from a large body of water slowly cooling between uses.
In most residential applications, tankless heaters are installed as point-of-use units serving a single outlet or a bathroom — one unit at the shower, another at the kitchen sink if required — rather than as central whole-house systems. This distributed installation approach is the most practical and cost-effective for most residential building configurations because it eliminates the long hot water pipe runs from a central storage geyser to distant outlets, which waste water (running the tap until hot water arrives) and lose heat along the pipe length.
The Genuine Advantages of Tankless Water Heaters
Elimination of standby heat loss. A conventional storage geyser is essentially a very well-insulated hot water tank connected to an electric heating element. It maintains water at a set temperature — typically 60–65°C — continuously, which means the heating element is cycling on and off throughout the day and night to replace the heat the tank loses to its surroundings despite its insulation. In a well-insulated modern geyser, this standby loss is relatively low. In older units with degraded insulation, it can be significant. A tankless heater consumes energy only when hot water is actually flowing, completely eliminating standby loss. In properties where hot water is used intensively for a few hours each day and the geyser otherwise runs idle, the energy saving from eliminating standby loss can be meaningful.
Continuous hot water supply. A storage geyser has a finite hot water capacity — when the stored hot water is exhausted by heavy use (multiple long showers in sequence, a large bath, significant hot water use in the kitchen simultaneously), there is a waiting period while the tank reheats. A tankless heater provides continuous hot water for as long as flow continues, limited only by the heater’s rated flow rate and temperature rise capacity. For households with multiple simultaneous users — or rental properties with multiple bathrooms — this eliminates the morning queuing problem that is a common complaint in older properties with undersized geysers.
Compact installation and space saving. A storage geyser and its associated pipework, expansion vessel, and pressure relief valve occupy significant wall or ceiling space. A point-of-use tankless heater is typically the size of a large book and can be mounted directly at the outlet it serves. In bathrooms with limited wall space, this is a genuine practical advantage. It also means that hot water provision can be added to a room that previously had none — a bathroom converted from a storage room, a kitchen extension, a staff quarters addition — without the complexity of connecting to a central hot water system.
Lower installation cost versus solar systems. Solar water heating systems deliver better long-term utility savings — once installed, they produce hot water from sunlight at no ongoing energy cost — but they require a higher upfront investment of $800–$2,500 depending on system size and configuration, plus roof-mounted panels and associated pipework. An electric tankless heater can be installed at a bathroom point-of-use for $80–$200 supply and installed, providing immediate hot water capability. For properties where the budget for water heating improvement is limited, or where the property’s roof is unsuitable for solar panels, the tankless option provides hot water functionality at a cost the budget can accommodate.
The Honest Limitations: What Tankless Heaters Cannot Do
Tankless electric water heaters have real limitations that must be understood before selecting them as the hot water solution for a specific property and market context. Failing to account for these limitations leads to installations that underperform expectations and generate tenant complaints that would have been avoided with the right system choice.
Complete electricity dependence. An electric tankless water heater is a purely electrical device. During a power outage, it produces no hot water at all. It has no stored warm water reserve that can be accessed for a short period after power fails, unlike a storage geyser which retains heat for several hours after power loss. In areas with frequent or extended power outages — which characterise the electricity supply situation in many developing markets — this is a significant functional limitation. Properties in areas with unreliable grid electricity need either a solar water heating system (which charges a storage tank during daylight hours and can provide hot water during grid outages), a generator, or a storage geyser that can retain heat through typical outage periods. Tankless heaters are appropriate only where grid electricity is reliable enough that tenants will not regularly experience the system being non-functional.
High instantaneous electrical demand. The speed with which a tankless heater heats water is achieved by applying a large amount of electrical power across a small amount of water in a short time. This translates to an instantaneous electrical demand of typically 3.5kW to 8kW per unit, depending on the heater’s rated output and the required temperature rise. In older residential buildings with limited electrical service capacity — a 20-amp or 30-amp main supply, for example — adding one or more tankless heaters may require an electrical service upgrade, which adds to the total cost of installation. This must be assessed before purchasing units, not after.
Flow rate limitations at higher temperature rise. A tankless heater’s performance is rated as a combination of maximum flow rate (litres per minute) and temperature rise (the difference between incoming cold water temperature and outlet hot water temperature). A unit rated at 10 litres per minute at a 25°C temperature rise will deliver less flow at a 35°C temperature rise, because more heat must be applied to the same volume of water. In climates where incoming cold water temperature is very low in winter, the effective flow rate at the outlet can be significantly below the rated maximum. For shower applications, flow rates below 6–8 litres per minute produce a weak, unsatisfying shower experience that generates tenant complaints.
How Hot Water Provision Affects Property Value
Hot water provision affects property value primarily at the threshold level: properties that have no functional hot water provision are at a significant market disadvantage in any mid-market or above context. The step from no hot water to functional hot water is a large value step. The step from functional tankless heaters to a high-quality solar water heating system is a smaller, more market-position-dependent value step.
Tankless electric heaters are therefore best understood as a cost-effective way to clear the hot water threshold at $80–$200 per bathroom point, rather than as a premium feature that commands a price premium of its own. For properties targeting the upper market where solar hot water is the appropriate specification, our guide on energy efficiency upgrades for rental properties covers solar water heating in the context of the broader energy efficiency investment programme.
Choosing the Right Unit: Specification Guidance
When selecting a tankless water heater for a specific installation, the following specification factors determine whether the unit will perform adequately:
Flow rate rating should be at least 8–10 litres per minute for a shower application, to ensure adequate pressure and flow for a satisfying shower experience. Lower-rated units (5–6 L/min) are adequate for basin-only applications but inadequate for showers.
Temperature rise rating should account for the local cold water temperature. In warm climates where incoming water is already 20–25°C, a 25°C temperature rise produces hot water at 45–50°C — adequate for shower use. In cold climates where incoming water can be 5–10°C, a higher temperature rise rating is required to achieve the same outlet temperature.
Electrical connection must be assessed against the property’s main electrical service capacity. A 7kW tankless heater requires a dedicated 32-amp circuit from the distribution board. An 8–10kW unit may require a larger dedicated circuit. This should be confirmed with a licensed electrician before purchase.
Our Plumbing and Hot Water Installation Services
Tankless electric water heater installation, storage geyser installation, solar water heating system installation, and full bathroom plumbing are all part of our Home Construction and Improvement Services. We assess each property’s electrical service capacity, water supply conditions, and usage requirements before recommending the appropriate hot water solution. We do not install systems that are inadequate for the application without first advising the client of the limitations. Contact us to arrange a site assessment.
Selling a property where hot water provision is currently absent or unreliable? Installing a basic point-of-use tankless heater at each bathroom and the kitchen before listing removes a buyer objection that would otherwise generate a price reduction request or cause the property to fail viewings. We can assess and install quickly as part of a pre-sale preparation programme. Contact us to discuss.
Leave a Reply