Commercial Tower – ROSC20 Commercial Gas System


40-storey commercial tower in Melbourne CBD. Upgrading of hot water plant to deliver energy reduction and durability without sacrificing performance.

Replacement of 12 year old original system, which was in poor condition, comprising Continuous Flow gas units of varied capacities and damaged (delivering reduced solar yield) original solar thermal panels.

System replacement to be conducted with minimal disruption to domestic hot water supply.

System Requirements:

Energy efficient, durable water heating system with an off-grid renewable solar PV component providing 4,400L at 50°C rise (delivered on average at 65°C) in the first hour and 4,000L each hour thereafter to meet the building’s water heating load.

ENERMAX System Solution:

  • 2 x ENERMAX 500L tanks SC500, comprising dual stainless steel coils providing hygienic hot water and high flow rate capability to the 40-storey tower.
  • 2 x Noritz 50L/min condensing Commercial Continuous Flow gas, 330MJ/Hr at 95% thermal efficiency as the main energy source.
  • 1 x Grundfos primary pump set for the system primary loop function.
  • 2 x ESW ROSC20 solar PV powered elements providing a total 4kW of solar yield from 12 x solar PV panels.

Original System:

Traditional design plant –

  • 8 x 199 to205MJ/Hr Continuous Flow (24, 26 and 27L/min) gas.
  • 2 x 430L mild steel storage tanks.
  • 12 x flat plate solar thermal collectors.

System Performance:

  • Footprint – Total plant footprint required – 2.2 sq mtrs (2000 x 1100mm), Original system 7.2 sq mtrs (4000 x 1800mm). Solar panels are located separately, on building roof.

  • Installation disruption – full hot water flow and temperature disruption was limited to less than 4 hours.

  • Performance – is delivering 4,400L at 65°C in first hour with an hourly recovery rate of 4,000L at 65°C. Servicing 3,500 occupants using 63 basins, 80 sinks and 41 showers through the tower.

  • Energy Reduction – ongoing monthly gas consumption reduction at higher delivered temperature rise, from installation (April 2019) even through traditional higher use Winter period.


This ENERMAX solution is a fit-for-purpose system. It provides clean hygienic heated water using condensing gas technology with solar PV energy input, exceeding the client targets for performance and energy efficiency and will continue to deliver energy savings over its life. Lifetime maintenance costs, particularly of the Continuous Flow gas units and solar PV vs solar thermal panels, will be reduced due to the unique ENERMAX system function.