Overview of the Problem – Unreliable Hot Water in an Older Californian Bungalow

At a property on York Avenue in Oakleigh VIC 3166, our team at Your Choice Plumbers was called out after the owners became fed up with their ageing Bosch 16H Hydro Power hot water system.

The home had been relying on the older continuous flow unit for some time, but the system had become increasingly unreliable. The pilot light was blowing out regularly, the water temperature was fluctuating badly, and the owners were no longer getting the steady hot water performance they expected.

The final failure came when the internal copper pipe coil burst, leaving the existing unit beyond practical repair.

This is exactly the type of situation where homeowners start asking, “why does my continuous flow hot water keep cutting out?” or “is an old Bosch Hydro Power worth repairing or should it be replaced?” As an experienced plumber Oakleigh, we often find that once older Hydro Power systems start suffering repeated ignition and heat-exchanger issues, replacement becomes the smarter long-term solution.

Why the Existing Bosch Hydro Power System Had Reached the End

The owners liked the idea of continuous flow hot water, but the older Bosch technology had become the problem.

These earlier Hydro Power units rely on older-style pilot and ignition arrangements that can become increasingly unreliable as the appliance ages. When the components wear out, homeowners often start experiencing:

  • pilot light outages
  • inconsistent burner operation
  • unstable water temperature
  • repeated relighting frustration

In this case, the failure of the internal copper coil confirmed that the unit had reached the point where replacement made more sense than trying to keep an ageing system alive.

This is something we often explain on hot water system repairs jobs, because while repairs are always worth assessing first, some older units eventually cross the line where they are no longer economical to keep going.

Pre-Installation Gas Safety Checks Before Replacement

Before carrying out any hot water replacement works, we performed a pre-installation gas pressure test on the consumer gas piping.

That step is important because before a new gas appliance is connected, the existing gas line must first be checked to confirm it is sound and leak-free.

We carried out this testing in line with the gas installation requirements referenced under AS/NZS 5601.1, which is critical whenever existing gas infrastructure is being reused for a new appliance.

This is something we often explain on gas leaks and gas appliance jobs, because safe gas work starts with testing the line properly before the new unit even goes on the wall.

Why the Rinnai 20 Was the Right Upgrade

For the replacement, we recommended a:

Rinnai 20 Continuous Flow Hot Water System

This was the right fit for the home because it offered:

  • reliable electronic ignition
  • precise temperature control
  • modern continuous flow performance
  • a much better day-to-day experience than the older Bosch Hydro Power system

Unlike the old manual pilot arrangement, the Rinnai system gives the owners a far more dependable “set and forget” hot water setup.

Coordinating the Electrical Upgrade for the New Unit

One important difference between the old Bosch Hydro Power and the new Rinnai 20 was the electrical requirement.

Because the new Rinnai uses electronic ignition and controls, it required a power point to be installed at the external unit location.

To make the upgrade work properly, we coordinated with a licensed electrician to install a weatherproof external GPO at the unit position.

That meant the new system could be installed cleanly and compliantly without relying on unsafe temporary power arrangements.

Removing the Old Unit and Installing the New Rinnai 20

Once the gas line had been tested and the electrical side was ready, we decommissioned the old Bosch unit and installed the new Rinnai 20.

We used a specialised valve kit to provide a clean and professional connection for:

  • the hot water line
  • the cold water line
  • the gas supply

This gave the installation a much neater final result and made future servicing easier as well.

The Rinnai unit and valve kit were sourced from Reece Plumbing Oakleigh.

Why the 50°C Pre-Set Configuration Was Important

The replacement Rinnai unit was supplied pre-set to 50°C.

This was an important part of the upgrade because it ensured the bathroom hot water delivery would remain within the safe and compliant range required under Victorian plumbing safety expectations for domestic sanitary fixtures.

That meant the owners were not only getting a new hot water unit — they were also getting a safer and more controlled hot water outcome without the need for additional tempering components in this particular setup.

This is something we often explain on temperature control valve and hot water safety jobs, because delivered hot water temperature matters just as much as appliance performance.

Post-Installation Gas Testing and Final Commissioning

Once the new Rinnai 20 had been installed, we carried out a final gas pressure test using a manometer to verify that the consumer gas line remained fully tight after the new appliance connection.

This confirmed:

  • there was no pressure drop
  • the gas line remained sound
  • the new installation was safe to place into service

We then fully commissioned the unit and verified the hot water was operating properly through the home.

That final verification mattered because this was not just an appliance swap — it was a full gas and hot water upgrade that needed to be proven safe at the end.

Why This Upgrade Was a Better Long-Term Outcome

This job is a very good example of when replacement is the better answer than repeated repairs.

The owners had already been dealing with:

  • unreliable pilot operation
  • fluctuating hot water
  • repeated inconvenience
  • eventual coil failure

By upgrading to the Rinnai 20, they now have:

  • stable continuous flow performance
  • no pilot relighting frustration
  • modern electronic ignition
  • cleaner and safer gas appliance operation
  • a much more dependable long-term hot water setup

Final Result and Client Outcome

Once the works were complete, the owners had:

  • the old Bosch Hydro Power removed
  • a new Rinnai 20 installed
  • pre- and post-installation gas testing completed
  • a new weatherproof power point coordinated for the unit
  • a clean valve kit installation
  • stable hot water with proper temperature control

The owners were very pleased to finally have reliable hot water again without the constant frustration of relighting the old system or dealing with temperature inconsistency.

Compliance with Australian Standards

This case directly related to the safe replacement and commissioning of a gas continuous flow hot water system, including gas testing in line with AS/NZS 5601.1 and safe hot water delivery considerations under AS/NZS 3500.4.

In practical terms, this meant the job was not just about changing one appliance for another. It also involved confirming the existing gas line was sound before installation, verifying it remained gastight afterward, and ensuring the new system delivered hot water in a safe and suitable temperature range for the home.

All work carried out by Your Choice Plumbers is completed in accordance with the relevant plumbing and gas standards so hot water replacements are safe, compliant, and properly commissioned from start to finish.

Our Home Plumbing Experts Approach

As part of our Home Plumbing Experts approach, we focus on both repair and prevention.

We include our complimentary Property Protection Audit with plumbing services to help homeowners understand hidden risks like excessive water pressure, unsafe hot water temperatures, and ageing flexible hoses before they turn into emergencies.

Find out more about our hot water system repairs, gas leaks, and temperature control valve services where hot water performance, gas safety, and compliant delivery all need to work together.

Looking for a Plumber in Oakleigh?

If you’re dealing with an unreliable continuous flow hot water system, an old Bosch Hydro Power unit, or want honest advice on whether repair or replacement is the smarter option, visit our Plumber Oakleigh page to learn more about how we help local homeowners.