PURPOSE: This rule sets standards for heat pump systems that use refrigerants in the closed-loop as the heat transfer fluid.

1. (1) Direct Expansion Heat Pump Systems. This type of system will no longer be allowed as of January 1, 2015. These types of systems utilize a network of copper tubing or other material installed in a pit, trench or vertically in a borehole. The refrigerant is circulated through the tubing allowing the heat transfer to take place. The ground coil must be installed by a method which prevents leakage of the refrigerant.
2. (2) Any heat transfer fluids used in a direct expansion heat pump system must be nontoxic and nonhazardous such as R410A, R407C, or others that are approved in advance by the division.
3. (3) Heat Pump systems utilizing refrigerants in their closed-loops may not be placed into vertical wells unless approval is received in advance from the division.

AUTHORITY: sections 256.606 and 256.626, RSMo 2000.* Emergency rule filed Nov. 16, 1993, effective Dec. 11, 1993, expired April 9, 1994. Original rule filed Aug. 17, 1993, effective March 10, 1994. Amended: Filed May 17, 2013, effective Dec. 30, 2013.

*Original authority: 256.606, RSMo 1991 and 256.626, RSMo 1985, amended 1991.