To help address the increased growth and needs in Geo Thermal installations, Merrill Manufacturing Company is launching the RGSEU and RGSE series. merrill mfg RGSEU and RGSE The Red Brass Geo Thermal Union Adapters and Ground Source Elbows are male thread by insert barb elbows.  Both series are equipped with a port for a Pete’s Plug and come in a variety of sizes to provide the convenience of a union fitting for any outlet direction.