Water Solutions

Recycle Waste Heat from Drain Water and HVACR Systems 

GreenFoX™ Drain Water Heat Recovery (GFX DWHR)

Captures the waste heat going down the drain and uses it to preheat incoming cold water. Simply replace a vertical section of the drainpipe. It needs only gravity and running water for year-around operation and continuous savings.

Get more hot water with less energy

Heat incoming cold water from 50° to 80°

Boost heater output up to 9.5 GPM

Increase GPM rating 30% - 50%


GreenFoX™ Drain Water Heat Recovery (GFX DWHR)


Drain water heat recovery devices improve efficiency by warming incoming GFX DWHR cold water with heat absorbed from draining warm water.
GFX DWHR systems do not replace existing hot water heating system, but rather enhance their performance by reducing the heating system work load and improving energy efficiency by preheating the incoming supply water entering the hot water heating system. Weather using tank, tankless, solar, and/or geothermal or any other type, the preheated water coming into the heating system will reduce the amount of energy required to bring hot water up to the operating set point of the system.


System coil and tube heat exchangers use Gravity Film eXchange Technology. As water goes down a vertical section of drain pipe, it naturally clings to the inner surface of the pipe in a very thin film. The heat from this film is transferred to the incoming fresh cold water circulating up through the copper coils around the outside of the heat exchanger (which is now part of the drain pipe). The incoming cold water is preheated before is goes into the water heater – it is in that way you are saving money and energy while increasing hot water capacity.

The heat exchanger becomes part of the drainage stack, usually in the basement, by replacing a vertical section of the drain line. The coils become part of the fresh water supply line by diverting the supply water through the heat exchanger. It can be installed with any combination of drainage pipe and fresh water piping (ie. ABS, PCV, cast iron, copper, PEX, etc). Only 4 plumbing connections are needed – 2 for the coil and 2 for the drain (using no-hub connectors). Units can be installed in the basement, 1st floor, 2nd floor or crawl space – virtually anywhere there is access to a sufficiently tall section of VERTICAL waste pipe having waste hot water flowing through it, along with access to a cold water supply line. Contact us for details on installation configurations. 


Since the heat exchangers diameter is the same as the existing drain, there is no clogging or build-up created. A completely passive system with no moving parts means there is no maintenance, ensuring long lasting operation for peak efficiency.

Code Compliance

Certified by independent organizations as a double-wall-vented heat exchanger approved for potable water use according to the Safe Drinking Water Act, safety tested and constructed in accordance with Federal, State, and Local plumbing codes.

• Intertek ETL/Warnock Hersey mark

• IAPMO PS 92 Standards for Heat Exchangers

• IAPMO 2012 Green Plumbing and Mechanical Supplement Code Section 606.0

• CSA B55.1 DWHR Performance Standard

• CSA B55.2 DWHR Safety Standard




DataFoX Waste Heat Recovery Monitoring

Data Logger

System Data Monitored

Supply & Drain Temperatures

Supply & Drain Delta T

Flow Rates (GPM)

Unit Heat Transfer Efficiency

Ambient Air Temperature

Heat Recovery Unit Efficiency

Scrolling 2 Line LCD Monitor

Removable SD Memory Card

Basic, Ethernet or WiFi connections


Customized to work with GreenFoX I AirFoX I PoolFoX




Commercial Dishwasher Solutions

Energy Recycling Drain Water Heat Recovery (DWHR)


Lower utility bills ~ year round savings

Raise the temperature of incoming water S heating costs EVERY MONTH!


Green Benefits




Commercial Laundries


AirFoX Heat Recovery Unit (desuperheater)

Energy Recycling ~ Air Conditioner Superheat Recovery


Heat Recovery Unit for Domestic Hot Water

From Residential and Commercial HVAC Systems


The AirFoX Heat Recovery Unit (desuperheater) captures waste heat discharged from the refrigerant cycle in an Air Conditioning or Heat Pump system. Then transfers that heat into the water heater tank – creating hot water. Not only does the AirFoX reduce the amount of energy required to provide hot water, it also improves the cooling efficiency of the Air Conditioner or Heat Pump while it is operating.

The refrigerant side of the AirFoX is installed in the refrigerant hot gas line between the compressor and condenser. If installed on a Heat Pump System – between the compressor and reversing valve. The water side is connected to the water heater tank to form a circulation loop. Power is drawn from the compressor contactor. Waste heat may be collected when the compressor operates, and the water circulating from the water tank is less than 140°F. A minimum refrigerant temperature of 125°F is also required to allow Heat Recovery Operation.






Superheat Recovery

Heat Water Increase SEER

Lower Refrigerant




Drain Water Heat Recovery

Cool Milk—Heat Water


$ Save millions of BTU’s

$ Extend equipment life

$ Raise system efficiency

$ Low or NO maintenance

$ Increase hot water supply

$ Reduce Carbon Emissions

$ Quick and painless lifetime ROI

$ Enhance tankless performance

$ Decrease equipment workload



for use in commercial

and industrial ice machines


Save energy and reduce freeze time!

Recycle “cold” energy using melted ice water

to pre-c hill incoming fresh water!

An inlet water pre-chiller add -on for

ice making equipment


By lowering the temperature of incoming water

• freeze time is reduced

• machine efficiency increased

 lessens work load


Green Benefits

• Zero Energy product

• Lowe r utility costs

• 30 year life

• 100% recyclable

• No maintenance


Applications include hotels, restaurants, bars and any other place that requires large volumes of ice, especially in warm climates!

• Available in 1 1/2” and 2” DWV diameter

• Custom designed systems available

• Manufactured to maximize thermal transfer

• Meets potable water standards & plumbing codes

 Double wall vented construction




Swing Green PDF Files



EMC_SwingGreen_Info_Folder_4.2.15 (1).pdf

Drain Water Heat Recovery - SG_GreenFoX_Y_Series_Rev14Ncsc.pdf

Compressor Heat Recovery - SG_AirFoX_Rev14N csc.pdf

Pool Heating - SG_PoolFoX_Rev14N




Swing Green DWHR 2015 ICC.pdf

Ice Machine Drawing - ArticFoX_G2-12.250.pdf

Ice Machine Drawing - ArticFoX_G2-12.375.pdf

Compressor Heat Recovery Drawing - AIR FOX installation.pdf



Drain Water Heat Recovery Explained  - Nat_SG_PH_YTSD



Massachusetts Technology Assessment Committee - 2014

Independent Study - ARL Performance Report R6K-410 Test.pdf



Case Studies

U. S. DOE - Gravity_Film_Heat_Exchanger_paper_SG.pdf


Ft Carson

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