(19)

(11)

EP 0 334 891 A1

(12)

(43) Date of publication: 04.10.1989 Bulletin 1989/40 (21) Application number: 88900429.0 (22) Date of filing: 11.12.1987

(51) International Patent Classification (IPC):  F24H 1/ 18( . ) F24H 9/ 00( . ) (86) International application number: PCT/US1987/003234 (87) International publication number: WO 1988/004392 (16.06.1988 Gazette 1988/13)

(84) Designated Contracting States: AT BE CH DE FR GB IT LI LU NL SE (30) Priority: 11.12.1986 US 19860940430 (71) Applicant: A.O. SMITH CORPORATION Milwaukee, WI 53223-0990 (US)	(72) Inventors: STUBBE, James, S. Milwaukee, WI 53208 (US) CHEVALIER, James, L. Mequon, WI 53092 (US) POW, Edwin, C. Menomonee Falls, WI 53051 (US) (74) Representative: Geissler, Bernhard, Dr. jur., Dipl.-Phys., et al  Patent- und Rechtsanwälte Bardehle . Pagenberg . Dost . Altenburg . Frohwitter . Geissler & Partner Postfach 86 06 20 D-81633 München D-81633 München (DE)