The United States Department has mandated manufacturers of equipment meet minimum energy standards and physical parameters residential applications (as opposed  to commercial) for Thru-The-Wall (TTW) systems, both air conditioner and heat pump. To assist you in determining whether your application meets the US DOE minimum standards we offer the following DOE specifications (10 CFR 430.2):

(1) Is manufactured prior to January 23, 2010;

(2) Is not weatherized;

(3) Is clearly and permanently marked for installation only through an exterior wall;

(4) Has a rated cooling capacity no greater than 30,000 Btu/hr:

(5) Exchanges all of its outdoor air across a single surface of the equipment cabinet; and

(6) Has a combined outdoor air exchange area of less than 800 square inches (split systems) or less than 1,210 square inches (single packaged systems) as measured on the surface described in paragraph (5) of this definition.

Further, the SEER and HSPF minimum requirements are defined as follows (10 CFR 430.32, page 268):

After January 23, 2010 there is a new technical definition that applies to TTW type systems, it is called "Space Constrained Product"

"Space constrained product" means a central air conditioner or heat pump (10 CFR 430.2, page 127):

(1) That has rated cooling capacities no greater than 30,000 BTU/hr;

(2) That has an outdoor or indoor unit having at least two overall exterior dimensions or an overall displacement that:

    (i) Is substantially smaller than those of other units that are:

        (A) Currently usually installed in site-built single family homes; and

        (B) Of a similar cooling, and, if a heat pump, heating capacity; and (ii) If increased, would certainly result in a considerable increase in the usual cost of installation or would certainly result in a significant loss in the utility of the product to the consumer; and

(3) Of a product type that was available for purchase in the United States as of December 1, 2000.

Further, the new Energy efficiency requirements are (10 CFR 430.32, page 350):

* SEER= Seasonal Energy Efficiency Ratio

* HSPF= Heating Seasonal Performance Factor