GFX Case Study

Hotel in Wellington, New Zealand

Courtesy of Frans Plugge, ECOsystems Ltd


Four GFX Units


GFX Installation

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As Installed

Equal Flow to Shower Option

Net Annual Savings:




1.67 years

1.14 years

GFX System:

Model S4-60 in a common drain serving 6 showers, 6 toilets, and 6 hand basins; preheated water fed just to the water heater, not to the fixtures.*

Water Temperature:

Cold: 60.8F [16C],
Hot: 140F [60C] (9/20/97)

Hot water Usage:

293 gallons/day [1110 liters/day]

Shower Flow Rates:

2.1 gpm [7.9 liters/min]

Shower Mix:

1.2 parts hot, 1 part cold

Cold Water Boost:

25F [14C] Avg.

Drain Water Cooling:

21F [11.7C] Avg.

Average Savings:

20.14 kwh/day x 5.41/kWh = $1.09/day
$379.78 per annum


Demand Savings:

1 kWh x $20.14 (demand tariff) x 12 months =$241.68




Equal Flow Option

These values are estimated for this installation, if it had used the equal flow option. Equal flow plumbing boosts efficiency substantially by sending some of the preheated water directly to the shower. A portion of the preheated water also feeds the water heater tank. Preheated water feeds the cold sides of the shower mixing valves, but not the toilets or sinks. This enables flow limiters within low-flow showerheads to automatically prevent surging.


Coil Inlet and Outlet Temperatures Over a 24 Hour Period

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All Four Inlet and Outlet Temperatures During Morning Peak

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2002 Waterfilm Energy, Inc.