These whole-house HEPA filters are available in two model sizes. Both are installed on the return side of a forced air system. The units include prefilters, large certified HEPA filters, and motor/blower assemblies. The larger unit handles 350 cfm and the smaller model is rated at 120 cfm. Normally installed in a bypass configuration, the unit will have no effect on the efficiency of the forced air system. The HEPA filter will capture at least 99.97% of the 0.3 micron, and larger, airborne particles drawn through it, says the manufacturer.

Enerzone Inc., 22 Pegler St., London, ON, Canada N5Z 2B5; 519-645-2411; 519-660-8525 (fax); enerzone@ (e-mail).