Is It OK To Power A 220v Tankless With Only 120v? - Electrical - Page 2 - DIY Chatroom Home Improvement Forum


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Closed Thread
 
Thread Tools Display Modes
Old 11-10-2012, 08:03 AM   #16
Licensed Electrical Cont.
 
Speedy Petey's Avatar
 
Join Date: Feb 2004
Location: NY State
Posts: 6,899
Rewards Points: 2,152
Default

Is it OK to power a 220v tankless with only 120v?


Quote:
Originally Posted by wonderworm View Post
I find it interesting that I get attacked but noone seems to have an answer to the single question I asked.
I find it interesting, even funny, that some folks consider not getting the exact answer they WANT on a message board as being "attacked".



Quote:
Originally Posted by wonderworm View Post
Will an entry level 240v tankless at 120volts produce roughly the same heat as a 120v tankless at 120volts? I think I'm just too outside the box for some here.
My answer would be a firm NO.
Pretty much every insta-hot water heater I have seen has had electronics and circuit boards. My guess is that they are designed to run at the voltage spec'd on the unit. Supply it with half that voltage and you let all the magic smoke out of the electronic components.
Standard storage type old-school water heaters do not have these electronics. Just mechanical thermostats and heating elements.

Advertisement

__________________
Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.
Answers based on the 2008 & 2011 NEC.
Speedy Petey is offline  
The Following 4 Users Say Thank You to Speedy Petey For This Useful Post:
Bobka (11-13-2012), k_buz (11-10-2012), mpoulton (11-10-2012), TTW (12-18-2012)
Old 11-10-2012, 09:15 AM   #17
Licensed Electrician
 
k_buz's Avatar
 
Join Date: Mar 2012
Location: SE Wisconsin
Posts: 4,343
Rewards Points: 2,006
Default

Is it OK to power a 220v tankless with only 120v?


Add to that the fact that if the unit is spec'd to run at 240V, you don't have an option to run it at 120V.
__________________
__________________________________________________ ______________
Answers based on the National Electric Code. Always check local amendments.


k_buz is offline  
Old 11-10-2012, 09:39 AM   #18
Licensed Electrical Cont.
 
Speedy Petey's Avatar
 
Join Date: Feb 2004
Location: NY State
Posts: 6,899
Rewards Points: 2,152
Default

Is it OK to power a 220v tankless with only 120v?


Quote:
Originally Posted by k_buz View Post
Add to that the fact that if the unit is spec'd to run at 240V, you don't have an option to run it at 120V.
But what if he reeeeeaaallly wants to??
__________________
Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.
Answers based on the 2008 & 2011 NEC.
Speedy Petey is offline  
Old 11-10-2012, 09:46 AM   #19
Licensed Electrician
 
k_buz's Avatar
 
Join Date: Mar 2012
Location: SE Wisconsin
Posts: 4,343
Rewards Points: 2,006
Default

Is it OK to power a 220v tankless with only 120v?


I completely forgot about the "REALLY wants to exception".
__________________
__________________________________________________ ______________
Answers based on the National Electric Code. Always check local amendments.


k_buz is offline  
The Following User Says Thank You to k_buz For This Useful Post:
Jim Port (11-13-2012)
Old 11-13-2012, 02:51 PM   #20
Newbie
 
Join Date: Jun 2008
Posts: 26
Rewards Points: 25
Default

Is it OK to power a 220v tankless with only 120v?


Quote:
Originally Posted by AllanJ View Post
Why not convert the line that is going to feed the tankless heater into a 240 volt line?

Install a double wide 240 volt double breaker for it, remove the neutral from the neutral bus at the panel, and connect that white wire to the other half of the double breaker. Disconnect all other receptacles, lights, etc. from the line, wire nutting the wire ends inside each box daisy chained along the way as a pass through only. (The tankless draws enough amps that the circuit should be dedicated to it.)
Now this is the type of outside the box solutions I'm talking about. I think your idea will work Allan. I spec'd a Chronomite 240v 7.2Kw tankless that will run on 30 AMPs. My existing wire is a dedicated 10-2 wire which can support 30AMPS of draw! Seems a perfect fit. Much better than the strongest 120v which only puts out 3.6Kw.
wonderworm is offline  
Old 11-13-2012, 03:05 PM   #21
Member
 
Join Date: Sep 2012
Location: Hillsboro, Oregon
Posts: 278
Rewards Points: 218
Default

Is it OK to power a 220v tankless with only 120v?


Quote:
Originally Posted by wonderworm View Post
Now this is the type of outside the box solutions I'm talking about. I think your idea will work Allan. I spec'd a Chronomite 240v 7.2Kw tankless that will run on 30 AMPs. My existing wire is a dedicated 10-2 wire which can support 30AMPS of draw! Seems a perfect fit. Much better than the strongest 120v which only puts out 3.6Kw.
I mentioned this in post #2 but you said you couldn't do that.
sgip2000 is offline  
The Following 2 Users Say Thank You to sgip2000 For This Useful Post:
mpoulton (11-13-2012), Speedy Petey (11-13-2012)
Old 11-13-2012, 03:14 PM   #22
JOATMON
 
ddawg16's Avatar
 
Join Date: Aug 2011
Location: S. California
Posts: 7,651
Rewards Points: 2,616
Default

Is it OK to power a 220v tankless with only 120v?


Quote:
Originally Posted by sgip2000 View Post
I mentioned this in post #2 but you said you couldn't do that.
Yep....you sure did.....

Quote:
Originally Posted by sgip2000 View Post
If possible, why not just wire it for 240V? A tankless running at less than full power will not heat very well.
and he sure did.....

Quote:
Originally Posted by wonderworm View Post
Unfortunately, it's not possible. My options are to buy a 220v wired as a 120v or 120v wired as a 120v. Do you think the 220v at 120v power will heat equally as poorly as the 120v tankless?
__________________
Even if you are on the right track, you will still get run over if you just sit there.

My 2-Story Addition Build in Progress Link ... My Garage Build Link and My Jeep Build Link
ddawg16 is offline  
The Following User Says Thank You to ddawg16 For This Useful Post:
mpoulton (11-13-2012)
Old 11-13-2012, 06:15 PM   #23
Newbie
 
Join Date: Jun 2008
Posts: 26
Rewards Points: 25
Default

Is it OK to power a 220v tankless with only 120v?


Quote:
Originally Posted by sgip2000 View Post
I mentioned this in post #2 but you said you couldn't do that.
Quote:
Originally Posted by sgip2000
If possible, why not just wire it for 240V? A tankless running at less than full power will not heat very well.

Sorry, from the phrasing of your brief comment it indicated like you were advising to run new thicker 240v wire to the location and why I said it was not possible. I'll update once I get it installed and tested.
wonderworm is offline  
Old 11-13-2012, 06:26 PM   #24
A "Handy Husband"
 
rjniles's Avatar
 
Join Date: Feb 2007
Location: South Carolina Low Country
Posts: 4,228
Rewards Points: 2,366
Default

Is it OK to power a 220v tankless with only 120v?


Quote:
Originally Posted by wonderworm View Post
Now this is the type of outside the box solutions I'm talking about. I think your idea will work Allan. I spec'd a Chronomite 240v 7.2Kw tankless that will run on 30 AMPs. My existing wire is a dedicated 10-2 wire which can support 30AMPS of draw! Seems a perfect fit. Much better than the strongest 120v which only puts out 3.6Kw.
Not what I would call "out of the box" thinking, but the most common way to wire a 240 only device.
__________________
Location:
Coastal South Carolina
rjniles is offline  
The Following User Says Thank You to rjniles For This Useful Post:
Speedy Petey (11-13-2012)
Old 11-14-2012, 10:25 AM   #25
Semi-Pro Electro-Geek
 
Join Date: Jul 2009
Location: Arizona, USA
Posts: 2,570
Rewards Points: 2,036
Default

Is it OK to power a 220v tankless with only 120v?


Quote:
Originally Posted by wonderworm View Post
Quote:
Originally Posted by sgip2000
If possible, why not just wire it for 240V? A tankless running at less than full power will not heat very well.

Sorry, from the phrasing of your brief comment it indicated like you were advising to run new thicker 240v wire to the location and why I said it was not possible. I'll update once I get it installed and tested.
There is no "240V wire". Almost all wire you can buy is 600V rated, and the rest of it is 300V rated. The thickness is pretty much the same. Wire is wire. What you connect it to matters.
__________________
I am a lawyer, but not your lawyer. And who cares anyways? We're here to talk construction. This is DIY advice, not legal advice.
mpoulton is online now  
Old 11-14-2012, 10:30 AM   #26
Member
 
Join Date: Sep 2012
Location: Western PA
Posts: 203
Rewards Points: 150
Default

Is it OK to power a 220v tankless with only 120v?


Quote:
Originally Posted by mpoulton View Post
There is no "240V wire". Almost all wire you can buy is 600V rated, and the rest of it is 300V rated. The thickness is pretty much the same. Wire is wire. What you connect it to matters.
To expand on that slightly.

The insulation (type and thickness) is the primary determinant of the voltage rating. The wire size and material determines the current capability.
Dave632 is offline  
The Following User Says Thank You to Dave632 For This Useful Post:
TTW (12-17-2012)
Old 12-14-2012, 04:15 PM   #27
Newbie
 
Join Date: Jun 2008
Posts: 26
Rewards Points: 25
Default

Is it OK to power a 220v tankless with only 120v?


Quote:
Originally Posted by sgip2000 View Post
For the 240v unit, it may use the same wiring as the 120v model, if it is straight 240v and not 120/240v.
Do you have space in your panel for a double pole breaker?
Here's the update after completing this install for anyone looking to do a similar job.

I removed an old leaking 20gal water heater that was in a utility closet that supplied a clothes washer, dishwasher and kitchen sink and replaced it with a 240v 7.2Kw tankless.

My copper pipe run was longer than recommended, 30'+ feet and because of that, during winter it takes a good 45 seconds for the pipe to warm up so expect similar if you also have a long pipe run. The water, (atleast during winter) only gets hottub hot but that is acceptable for me. I used the existing #10 wire and simple moved the white neutral wire to the second pole on a double pole breaker to convert the wiring to carry 240v. And painted the white wire red to designate that that wiring was now 240v or "hot". I got rid of the now unneeded TPR valve and used standard 1/2'' to 1/2'' stop valves off the wall and standard 1/2'' to 1/2'' flexible toilet connections so the install was cheap and easy.

The result is I now have a good looking clean closet install on the wall with tons of new storage, my electric bill is already dropping and I never have to worry about a cracked leaking tank flooding my house ever again. Thanks to sgip2000 and allanj for the idea.

Last edited by wonderworm; 12-16-2012 at 07:26 PM.
wonderworm is offline  
Old 12-14-2012, 04:43 PM   #28
A "Handy Husband"
 
rjniles's Avatar
 
Join Date: Feb 2007
Location: South Carolina Low Country
Posts: 4,228
Rewards Points: 2,366
Default

Is it OK to power a 220v tankless with only 120v?


What size (amp)2 pole breaker did you use? According to the manufacture, you need a minimum 40 amp breaker with #8 wire for this heater.

Removing a unneeded TPR valve says "Danger- Will Robinson"
__________________
Location:
Coastal South Carolina
rjniles is offline  
Old 12-14-2012, 09:37 PM   #29
Newbie
 
Join Date: Jun 2008
Posts: 26
Rewards Points: 25
Default

Is it OK to power a 220v tankless with only 120v?


repost.

Last edited by wonderworm; 12-14-2012 at 10:24 PM.
wonderworm is offline  
Old 12-14-2012, 09:47 PM   #30
Newbie
 
Join Date: Jun 2008
Posts: 26
Rewards Points: 25
Default

Is it OK to power a 220v tankless with only 120v?


Quote:
Originally Posted by rjniles View Post
What size (amp)2 pole breaker did you use? According to the manufacture, you need a minimum 40 amp breaker with #8 wire for this heater.Removing a unneeded TPR valve says "Danger- Will Robinson"
The chronomite that puts out 7.2Kw requires 30amps with 10 guage wire. I have the 40 amp handy but so far I have been able to run it on the 30amp double pole without it tripping the breaker once and 10 gauge wire is rated for 30amps. Checked the wire after 10 minutes of continuous operation and it was not hot.
"Tankless" has no "tank" thus no pressure build up so TPR valves are not required but you already know that, right?
But don't take my word for it, ask a manufacturer. "Installation of our tankless water heater is quick and easy. Under normal conditions, it requires no pressure relief valve. "

Advertisement


Last edited by wonderworm; 12-16-2012 at 07:27 PM.
wonderworm is offline  
Closed Thread


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Power 120V Pump from a 240V circuit RoberTX Electrical 26 07-06-2011 12:43 AM
How do I get power to a new ceiling fan? sestivers Electrical 12 04-25-2011 03:11 PM
hooking up dryer....bronx ny code SURFBUG Appliances 6 10-14-2008 10:41 PM
need power for 120v to 12v undercabinet lights robin hood Electrical 2 02-26-2008 04:43 PM
Partial power on same fuse! joyjam Electrical 5 07-10-2005 11:23 PM




Top of Page | View New Posts