yes GlennH ......
the manufacturer has a warranty;

Quote
This warranty does not apply to: (a) damage due to lightning or conditions beyond the control of SJE-Rhombus; (b) defects or malfunctions resulting from units not installed, operated, or maintained in accordance with instructions provided, applicable local codes, ordinances, or accepted trade practices; (c) failures resulting from abuse, misuse, accident, or negligence; or (d) units repaired and/or modified without prior authorization from SJE-Rhombus.

the link is here

however , there is a installation guide in PDF file form here that pictures a 'direct wire' scenario, so they apparently advocate this method.

there is an e-mail @ the site for further inqury:contact: SJE-Rhombus, P.O. Box 1708, Detroit Lakes, MN 56502 USA or phone: 218-847-1317, fax: 218-847-4617, email: sje@sjerhombus.com

ps~ Wirenuttt hauled me outta the last tank as i ranted on about this.... [Linked Image]