Q&A: Point-of-use water heaters

Q:
I’m looking for information on instantaneous electric water heater taps for sinks. I’m considering them to address the water and energy inefficiencies associated with the long pipe runs from my current water heater to kitchen, bathroom and laundry sinks.

I’m aware of instantaneous tap water heaters without storage and with integrated lever taps for this application, and these are what I’m most interested in hearing from people about.
With the shower, similar issues and savings opportunities arise, but the much less frequent use (typically once a day per person) make showers a much smaller opportunity to save water and energy by this means.

However, shower-specific instantaneous water heaters are available (which differ from sink units), so I’m happy to hear any ATA views on those as well.
For example, has there been a ReNew article reviewing any of these in relatively recent times? I remember seeing adverts for these in ReNew at some time in the past.
—Paul Riordan

A:
We haven’t reviewed such units, although several have appeared in the Products section of ReNew. These include units from www.rezi.com.au, www.stiebel.com.au, www.heyprestohotwater.com.au, www.gleamoushotwater.com.au, www.microheat.com.au and www.zipindustries.com.

They are all of similar efficiency (i.e. 100%); the main issue is the electrical circuit. The tap-integrated units generally work with a regular 10A power point or standard wiring, whereas the 15A and greater units (shower models seem to be rated around 5000 to 6000 W, or 20 to 25 A) need a dedicated circuit. The larger units are all three-phase and are not usually suitable for domestic installations unless three-phase power is available in the home.

These units can vary enormously in price and some are more repairable than others. Make sure you get one with an easily replaceable element if possible, and ensure spare elements are available.

The other thing to be aware of is the level of heating provided. Most of the single-phase units, especially the tap-integrated units, will only raise the water temperature by 10 to 20 °C for a reasonable flow rate, which might be fine in warmer climates, but if you have colder water temperatures they may not do the job. Check the specifications for each unit at the maximum flow rate required.
—Lance Turner

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