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General => IHADAV8 Playground => Topic started by: earlbrown on October 09 2011, 05:39:52 PM

Title: any electritions or plumbers here?
Post by: earlbrown on October 09 2011, 05:39:52 PM

My hotwater heater has been leaking lately and I'd like to switch over to a tankless unit to save space. Pricewise they seem to be about the same so now's the time to change if I'm going to.

What I've got right now is a 30A 220V feed to my current 40gal unit. Since I'm in GA I know the incoming water temp is a little over 85F in summer and I think the wintertime temp is around 50F. I shower at around 110F~115F and I've got a standard flow shower head.
 
I've been trying to do a search to see what the most powerful tankless is that will use a 30A feed, but none of the sites I've found list them like that. They're listed by need.

Title: Re: any electritions or plumbers here?
Post by: Steve Wood on October 09 2011, 07:11:56 PM

this place shows current requirements 

for example   http://www.plumbersurplus.com/Prod/Eemax-EX65-Flow-Controlled-Electric-Tankless-Water-Heater/10342/Cat/474 (http://www.plumbersurplus.com/Prod/Eemax-EX65-Flow-Controlled-Electric-Tankless-Water-Heater/10342/Cat/474)

Title: Re: any electritions or plumbers here?
Post by: daveismissing on October 09 2011, 07:27:12 PM

I bet they all show watts which you can then divide by 240volts to get the current

Title: Re: any electritions or plumbers here?
Post by: earlbrown on October 09 2011, 07:27:57 PM

Damn. That's what I was afraid of. 27A and only 22F temp rise at 2GPMs.  No where near enough.



During that post I forgot to ask about being able to use a larger main breaker in my box (if I need too). Right now I have a 200A but all the breakers add up to over 200.  Not sure if I need to go through heroics to get a tankless (which will get me another conventional unit) or if I can fly with what I have.

Title: Re: any electritions or plumbers here?
Post by: daveismissing on October 09 2011, 09:27:11 PM

Main breaker is sized by the entrance cable

Title: Re: any electritions or plumbers here?
Post by: earlbrown on October 09 2011, 09:52:35 PM

Is it common practice to size the main breaker on the maximum the entrance cable will feed?  Or based on what the house needs plus a buffer?

Title: Re: any electritions or plumbers here?
Post by: daveismissing on October 09 2011, 10:03:01 PM

Entrance cable is expensive  esp if it's buried so I expect they size it near the limits of the
service the original electrical permit states. Believe there are some jurisdictional y varying practices within what would be allowed by the NEC so answers are difficult without local knowledge.

Title: Re: any electritions or plumbers here?
Post by: earlbrown on October 09 2011, 10:25:30 PM

No idea what my entrance cable is sized at.

 All I know for sure is that it's aluminum and ran in the air. Not sure on the gauge of the cables.

Title: Re: any electritions or plumbers here?
Post by: Charlief1 on October 10 2011, 12:39:37 PM

Is your place all electric Earl? If not you might want to look into a gas unit.