Overview of the Problem – Burst Hot Water Cylinder in a Large Family Home

At a property on Armstrong Drive in Rowville VIC 3178, our team at Your Choice Plumbers was called out after the home’s Vulcan 135L hot water system burst and failed completely.

This was not just a normal hot water replacement. The family had six people in the house and had already been struggling with hot water running out during peak times, even before the cylinder failed. That meant replacing the old unit with another standard 135L system was never going to be the right long-term answer.

This is exactly the type of situation where homeowners start asking, “what hot water system is best for a large family?” or “should we replace a storage unit with continuous flow?” As an experienced plumber Rowville, we often find that once a growing household starts running out of hot water regularly, a like-for-like replacement is not always the smartest move.

Why a Standard Replacement Was Not Enough

The original Vulcan storage unit had failed, but the bigger issue was household demand.

For a family of six, the old setup was already under pressure during busy periods, especially when multiple showers or hot water demands happened close together.

That meant the owners needed more than just a new appliance — they needed a hot water solution that actually matched the way the family used the home.

This is something we often explain on hot water system repairs and replacement jobs, because the right hot water system depends not just on what failed, but on what the household really needs moving forward.

Comparing the Best Gas Hot Water Options for the Family

Because the owners wanted to stay with gas, we presented them with two strong large-family options.

Option 1: Rheem Stellar 360

We explained that the Rheem Stellar 360 is a very strong high-recovery storage option, with:

  • a 160L tank
  • around 200L per hour recovery
  • approximately 360L first-hour delivery

It is a very capable solution for large families and does not require an electrical point.

Option 2: Rinnai B26 Continuous Flow

We also explained the advantages of the Rinnai B26, which offers:

  • continuous flow hot water
  • no stored hot water limit
  • hot water on demand
  • a strong long-term solution for homes wanting to avoid ever “running out” again

After weighing up both options, the owners chose the Rinnai B26 because they wanted the peace of mind of effectively unlimited hot water for the household.

Why the Rinnai B26 Needed More Than a Straight Swap

Although the Rinnai B26 was the best performance choice for the family, it was not a basic changeover.

To install the unit properly, the home needed:

  • a new power point
  • a dedicated larger gas line
  • correct water pipe sizing at the appliance
  • pressure protection for the home

That meant the job became a full system reconfiguration rather than just replacing one heater with another.

Installing a Properly Sized Gas Supply for the New Unit

One of the most important parts of the project was the gas supply upgrade.

Following the gas sizing requirements referenced under AS/NZS 5601.1, the existing gas line was not large enough to support the new Rinnai B26 correctly.

To solve that, we installed a new 10-metre dedicated gas line from the meter using 25mm hard-drawn copper.

All joints were completed using:

  • B-Press fittings
  • our Rothenberger crimping tool

This gave the installation:

  • correct gas capacity for the new unit
  • a clean and professional finish
  • strong mechanical joints
  • a much better long-term supply arrangement for the appliance

This is something we often explain on gas leaks and gas appliance jobs, because undersized gas pipework can cause serious performance and safety issues if not corrected properly during installation.

Water Pipe Upsizing to Match Manufacturer Requirements

To comply with the Rinnai installation requirements and ensure proper hot water flow performance, we also upsized the existing 15mm hot and cold water pipes to 20mm for the first 1.5 metres of the installation.

That was an important part of the job because it helped ensure:

  • correct appliance flow
  • better system performance
  • compliance with the manufacturer’s installation guide
  • a more professional finished setup overall

Pressure Testing Revealed Another Important Issue

During the job, we also carried out a water pressure check and found the property was running at 720 kPa.

That is well above the 500 kPa maximum referenced under AS/NZS 3500 and would have placed unnecessary stress on:

  • the new hot water unit
  • the home’s tapware
  • toilet internals
  • flexible hoses
  • the wider plumbing system

This is something we often explain on pressure limiting valve and PRV installation jobs, because installing a brand-new hot water system into an over-pressured house can shorten the life of the unit and the rest of the home’s fixtures if the pressure is not corrected.

Installing a Pressure Reducing Valve at the Meter

To protect the new hot water installation and the home generally, we installed a:

Zurn 20mm right-angle Pressure Reducing Valve

This was fitted at the water meter and adjusted to bring the home back to a safe and compliant operating pressure.

That meant the family now had:

  • a new high-capacity hot water system
  • properly sized gas supply
  • compliant incoming water pressure
  • better overall plumbing protection across the house

Electrical Coordination and Final Gas Testing

Because the Rinnai B26 requires power, our licensed electrician installed the necessary power point as part of the project.

Once all plumbing, gas, and electrical components were in place, we completed a final manometer gas leak test with all appliances operating. This confirmed the new 25mm gas line and associated connections were fully sound and ready for service.

That final testing stage was critical because this was not just a hot water changeover — it was a full appliance infrastructure upgrade.

Final Result and Client Outcome

Once the works were complete, the family had:

  • the failed Vulcan 135L unit removed
  • a new Rinnai B26 continuous flow system installed
  • a new 25mm dedicated gas line
  • upsized water pipework at the unit
  • a new pressure reducing valve at the meter
  • reliable hot water supply for a large family household

Most importantly, they no longer had to worry about running out of hot water during busy times.

Compliance with Australian Standards

This case directly related to the gas sizing and installation requirements referenced under AS/NZS 5601.1, together with the residential pressure-control requirements referenced under AS/NZS 3500, which requires water pressure to be regulated to a maximum of 500 kPa.

In practical terms, this meant the job was not just about replacing a burst storage heater. It also involved correctly sizing the gas line for the new continuous flow system, ensuring the water connections suited the appliance, and protecting the whole installation from excessive mains pressure.

All work carried out by Your Choice Plumbers is completed in accordance with the relevant plumbing and gas standards so large-family hot water upgrades are safe, compliant, and built for long-term reliability.

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 pressure limiting valve and PRV installation services where hot water performance, gas safety, and pressure protection all need to work together.

Looking for a Plumber in Rowville?

If you’re replacing a failed hot water system, need a larger-capacity setup for a growing family, or want the gas and pressure side of the installation done properly from the start, visit our Plumber Rowville page to learn more about how we help local homeowners.