Apparatus and method for cleaning HVAC cooling coils

1. An apparatus for cleaning HVAC cooling coils, said apparatus comprising a supply and collection assembly having:

a housing defining an interior space for containing a quantity of cleaning solution;

a pump having a pump inlet positioned to be in fluid communication with the cleaning solution, said pump being constructed and arranged to deliver the cleaning solution to a supply outlet of said supply and collection assembly in a volume falling within a range of approximately 40-70 gallons per minutes (GPM);

a vacuum source having a vacuum inlet positioned to be in fluid communication with an ullage space such that the vacuum source creates negative pressure in the ullage space during operation;

a collection inlet in fluid communication with said ullage space, the cleaning solution being returned to the interior space through the collection inlet during operation of the vacuum source;

a nozzle device in fluid communication with said supply outlet via outlet piping, said nozzle device configured to deliver the volume of cleaning solution collectively though a plurality of apertures defined therein to a surface of an HVAC coil unit at a pressure no greater than 80 psi;

a fluid return tool in fluid communication with said collection inlet via return piping, said fluid return tool configured to collect used cleaning solution from the HVAC coil unit,

wherein said fluid return tool is positionable with respect to the HVAC cooling coils separately from said nozzle device.

2. An apparatus as set forth in claim 1 , further comprising a filter assembly along said return piping between the fluid return tool and the collection inlet.

3. An apparatus as set forth in claim 2 , wherein said filter assembly comprises a hydrocyclonic filter.

4. An apparatus as set forth in claim 3 , further comprising:

an electrically-controlled flush valve in fluid communication with a collection container of said hydrocyclonic filter; and

control circuitry operative to open and close the flush valve so as to empty the collection container.

5. An apparatus as set forth in claim 1 , further comprising air supply piping configured to introduce compressed air into the cleaning solution being delivered from the supply outlet.

6. An apparatus as set forth in claim 5 , further comprising an electrically controlled valve in said air supply piping, said valve operative to pulsate introduction of the air into the cleaning solution at a predetermined frequency.

7. An apparatus as set forth in claim 1 , further comprising upper and lower level switches in said interior space of said housing.

8. An apparatus as set forth in claim 7 , wherein said upper level switch is operative to cut off power to the pump if a threshold upper level of the cleaning solution is reached.

9. An apparatus as set forth in claim 7 , wherein said lower level switch is operative to open a fresh water supply port if a threshold lower level of the cleaning solution is reached.

10. An apparatus as set forth in claim 1 , wherein said pump is located entirely within said housing of said supply and collection assembly.

11. An apparatus as set forth in claim 10 , wherein said vacuum source comprises a motor located external to said housing of said supply and collection assembly.

12. An apparatus for cleaning HVAC cooling coils, said apparatus comprising:

a supply and collection assembly having:

a housing defining an interior space for containing a quantity of cleaning solution;

a pump constructed and arranged to deliver the cleaning solution to a supply outlet of said supply and collection assembly in a volume falling within a range of approximately 40-70 gallons per minutes (GPM);

a vacuum source having a vacuum inlet positioned to be in fluid communication with an ullage space such that the vacuum source creates negative pressure in the ullage space during operation to return the cleaning solution through a collection inlet;

a nozzle device in fluid communication with said supply outlet via outlet piping, said nozzle device configured to deliver the volume of cleaning solution collectively through a plurality of apertures defined therein to a surface of an HVAC coil unit;

a fluid return tool in fluid communication with said collection inlet via return piping, said fluid return tool configured to collect used cleaning solution from the HVAC coil unit; and

wherein said fluid return tool is positionable with respect to the HVAC cooling coils separately from said nozzle device.

13. An apparatus as set forth in claim 12 , further comprising a filter assembly positioned to filter particulate from said cleaning solution as said cleaning solution circulates, wherein said filter assembly comprises a hydrocyclonic filter.

14. An apparatus as set forth in claim 12 , further comprising air supply piping configured to introduce compressed air into the cleaning solution being delivered from the supply outlet.

15. An apparatus as set forth in claim 14 , further comprising a mechanism operative to pulsate introduction of the air into the cleaning solution at a predetermined frequency.

16. An apparatus as set forth in claim 15 , wherein said predetermined frequency is less than approximately 36 Hz.

17. An apparatus as set forth in claim 12 , wherein said nozzle device comprises a delivery face having a substantially planar surface for juxtaposition on the surface of the HVAC coil unit, a plurality of apertures being defined in said delivery face for passage of the cleaning solution.

18. An apparatus as set forth in claim 17 , wherein said apertures are oriented at a predetermined angle relative to the substantially planar surface of the delivery face.

19. An apparatus as set forth in claim 18 , wherein said predetermined angle falls within a range of approximately 45 degrees to approximately 53 degrees.