Question about Bosch PowerStar AE9.5 AE9.5 Point-of-Use Electric Tankless Water Heater...

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Connecting a AE9.5

Specifications tell you to use #8 wire for 40A. Do I use #8/2 or #8/3 wire.
Thanks Paul

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  • pplasschaert Mar 31, 2009

    Hi muttandjeff,

    Having followed your advice the water heater worked perfect. Problem arose soon after installation. The thermal kickout switch needs to be reset about ones a day. Bosch service suggested to backflush did not solve the problem. Use only one heating is not hot enough ,120F. After 3 contacts with Bosch service to resolve this problem the lady service tech?? cut me off with "Good luck sir have a nice day" after I told them about the elements are only 10.7 Ohms and produce much more heat than specified at 240V. (Measured 190+F). Thermal switch will kick out about 1 min after shut-off I observed.

    In all the unit heats but I did not sign up for all this hasle and then be rebuffed by my friends at Bosch.



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I would use # 8-2-with ground to have positive grounding at device , not 8-3 witch is more costly , also copper only no aluminum

Posted on Feb 01, 2009


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