By W. Bruce Longino, P.E., LEED AP
Needlepoint bi-polar ion generators are ever present in Georgia school systems and for great reasons.
Bi-polar ions are nature’s sanitizers. In the mountains and at the sea shore they are plentiful because of the increased solar radiation in the mountains and wave action at the shore. In these locations water molecules in the air are split into positively charged hydrogen atoms and negatively charged OH molecules. However inside our building there are basically no ions. What nature does in the mountains and at the shore we must do electronically in our buildings.
There are many different styles of needlepoint bi-polar ion generators. Each HVAC system type has a special type of needlepoint bi-polar ion generator. Some mount at the supply fan inlet, some are duct mounted and some mount after the filter but before the cooling coil. The later is what this article is about.
All three locations of the needlepoint bi-polar ion generator will do many wonderful things:
- Allow the designer to reduce the amount of outside air using the ASHRAE 62.1 IAQ method. This is possible because the ions clean the re-circulated air of Contaminates of Concern.
- The ions kill pathogens such as bacteria, viruses and mold in the duct system.
- The ions kill pathogens such as bacteria, viruses and mold in the building air.
- The ions kill pathogens such as bacteria, viruses and mold on the building surfaces.
- The ions cause the small dust particles to agglomerate in to larger particles so that the filters can remove them.
- Reduces allergens, such as pollen.
- Reduces odors and volatile organic compounds (VOCs)
Then if you place the needlepoint bi-polar ion generator after the filter but before the coil as shown below you get additional advantages:
- You keep the cooling coil face clean like a UV lamp does.
- Unlike the UV lamp you also keep inside the fins clean as ion go through the coil.
- You keep the drain pan clean.
I believe it is clear that if you install the needlepoint bi-polar ion generator at the supply fan inlet or in the supply duct the building Owners get many advantages. However if you mount it after the filter and before the cooling coil, you get even more advantages.
As great as this technology is it actually saves more money than it costs to install. As an example on an average High School in Georgia, the school costs about $300 K less to build and $30 K less each year to operate. This is because the outside is reduced from 15 to 5 CFM per student. This makes the Dedicated Outside Air equipment 67% smaller. This also reduces the structural an electrical costs.