I recently purchased an instant water heater for my house from (www.tankless.com) - model number 4.12. This 240V heater has four elements each rated at 7200W. The heater came with a subpanel that houses 4- double pole 30 amp breakers. According to the instructions, I'm to wire this subpanel into my main panel.

I will be mounting the water heater right next to my main panel in an utility room. My question is, since I'm mounting the heater close to my main panel, do I need to install the subpanel that came with it? Wouldn't I be able to wire directly to my main panel using the 30 amps breakers that came with the unit?

I looked at the NEC (422.11 F) and it seems like a subpanel is required but I don't understand the logic. Any comments?

Thanks,
Scott

 

They probably give you the subpanel because almost eveyone doesn't have 8 empty spaces in their panelboard. If the model breakers match an acceptable model that is listed on the door of your existing panelboard, then go ahead and relcocate them. If not, then put a 2 pole breaker of the recommended size in your main panel, and feed the sub panel.

 

They give you (read they charge you for) the sub-panel to serve as the disconnecting means for servicing the unit as required by 422.11 (F). The way I interpret the section is that the sub-panel is a requirement and you need to install it.