Help Needed Choosing 220v Or 120v Tankless Water Heater And Proper Amperage - Electrical - 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!

Reply
 
Thread Tools Display Modes
Old 11-08-2012, 04:38 PM   #1
Newbie
 
Join Date: Jun 2008
Posts: 26
Rewards Points: 25
Default

Help Needed Choosing 220v or 120v Tankless Water Heater and Proper Amperage


The water heater that feeds a clothes washer and a kitchen sink went out and I'm going to replace it with a tankless.

I have both a dedicated 120v line with a 30amp breaker to use or I can have the electrician tap into the 220v line that powers the living room airhandler.

My question is this: The current breaker on the 220v line is 30amps. The 220v tankless needs up to a 60 amp breaker. If an electrician taps into that 220v wire and adds the 220v tankless on it, can he then just upgrade the total amps on the breakers to 90amps to ensure that both can run at the same time without tripping the breaker?

Advertisement

wonderworm is offline   Reply With Quote
Old 11-08-2012, 04:51 PM   #2
Electrical Contractor
 
jbfan's Avatar
 
Join Date: Jun 2004
Location: Newnan GA
Posts: 5,960
Rewards Points: 2,316
Default

Help Needed Choosing 220v or 120v Tankless Water Heater and Proper Amperage


You are going to have to run a new circuit for the water heater.

Advertisement

__________________
Yes I am a Pirate, 200 years too late. "Jimmy Buffett"
jbfan is offline   Reply With Quote
Old 11-08-2012, 05:06 PM   #3
Newbie
 
Join Date: Jun 2008
Posts: 26
Rewards Points: 25
Default

Help Needed Choosing 220v or 120v Tankless Water Heater and Proper Amperage


So when you mean run a new circuit you mean I need to buy about 60ft of 240v copper line and run it behind all the sheetrock to the breaker box to create a dedicated line to the breaker box??

Isn't there another way to use a 240v tankless? The room it will be in is a utility room that has 240v line going to a dryer, the furnace, and small air handler for just the living room. Per the breaker box, I have dual pole 40amp breakers for the furnace and dual pole 30amp breakers for the air handler.

If I can't do that then my other option is to use the dedicated 120v line which currently powers the 40g water heater. This line is on a 30amp dual pole breaker so it will work if I buy a 110-120v tankless but from what I have read, i'm worried that the 120v tankless will only push warm water (not hot) when washing clothes since clothes washers use 2-2.5 gpm usually.

Anyone know the GPM flow for those new energy efficient front loading washers? Maybe a 120v tankless will be enough for one of those front loading washers.
wonderworm is offline   Reply With Quote
Old 11-08-2012, 05:08 PM   #4
Member
 
Join Date: Sep 2012
Location: Western PA
Posts: 203
Rewards Points: 150
Default

Help Needed Choosing 220v or 120v Tankless Water Heater and Proper Amperage


I'm confused. (Not a rare occurrence )

How can a tankless heater be OK on a 30Amp 120V circuit, yet need 60A @ 240V?
Dave632 is offline   Reply With Quote
Old 11-08-2012, 05:12 PM   #5
Licensed electrician
 
Join Date: Sep 2007
Location: Maryland
Posts: 8,011
Rewards Points: 2,820
Default

Help Needed Choosing 220v or 120v Tankless Water Heater and Proper Amperage


You may need to upgrade your entire service to allow the tankless to work.

The current water heater is not 120 if fed from a 2 pole 30 amp breaker.
__________________
Answers based on the National Electrical Code. Local amendments may apply. Check with your local building officials.
Jim Port is online now   Reply With Quote
Old 11-08-2012, 05:17 PM   #6
Newbie
 
Join Date: Jun 2008
Posts: 26
Rewards Points: 25
Default

Help Needed Choosing 220v or 120v Tankless Water Heater and Proper Amperage


Quote:
Originally Posted by Dave632 View Post
I'm confused. (Not a rare occurrence )
How can a tankless heater be OK on a 30Amp 120V circuit, yet need 60A @ 240V?
I haven't bought the tankless yet.

My choices are to buy a 240v tankless that requires 50-60amps

Or to buy a 120v tankless that requires 30amps.

There is already a 120v wire going right to the spot and this would be the easiest install but I'm worried that it will be too weak to provide hot water to a clothes washer. It would provide heat to a washing machine and 1 sink.

If I buy the 240v tankless, I would tap into the furnaces 220v line (about 4 feet away) and then upgrade the breakers to something alot higher than dual pole 40amp. (I'm asking if it's feasable to go the 240v route or if a 120v may be sufficient).
wonderworm is offline   Reply With Quote
Old 11-08-2012, 05:21 PM   #7
Newbie
 
Join Date: Jun 2008
Posts: 26
Rewards Points: 25
Default

Help Needed Choosing 220v or 120v Tankless Water Heater and Proper Amperage


Quote:
Originally Posted by Jim Port View Post
The current water heater is not 120 if fed from a 2 pole 30 amp breaker.
Thanks, I think it is 2 pole because it says 30amp and it takes up 2 full spaces in the electrical panel where as other 20 amp breakers are only taking up 1 slot. Is that 2 pole?
For the water heater, the label on it says 120v so I'm assuming it is a 120v 40 gallon water tank. Are most water heaters 220v??
wonderworm is offline   Reply With Quote
Old 11-08-2012, 05:28 PM   #8
JOATMON
 
ddawg16's Avatar
 
Join Date: Aug 2011
Location: S. California
Posts: 7,651
Rewards Points: 2,616
Default

Help Needed Choosing 220v or 120v Tankless Water Heater and Proper Amperage


I have a feeling that you do not understand ckt amperage and associated wiring.

The 240Vac tankless is going to use about 14,000 watts and would need #6 AWG wire.

The 120Vac unit would use about 3600 Watts and could get by with #10 AWG wire.

If you attempt to install a 50 or 60A breaker for the 240Vac using your existing wiring...you are going to melt the wire and likely start a fire.

Instead or looking at tankless units based on voltage and current, sit down and figure out the potential hot water GPM the washer needs.....then find a tankless unit that will supply that amount....

Once you have that figured out....hire an electrician to hook it up. Not that you can't do it, but it's my understanding that most warranties for those tankless units stipulate that they are installed by a qualified person.
__________________
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 online now   Reply With Quote
Old 11-08-2012, 05:29 PM   #9
Electrical Contractor
 
jbfan's Avatar
 
Join Date: Jun 2004
Location: Newnan GA
Posts: 5,960
Rewards Points: 2,316
Default

Help Needed Choosing 220v or 120v Tankless Water Heater and Proper Amperage


Most water heaters are 240, but small 6 to 10 gallon one can be 120.
You can not tap into any line and just upgrade the breaker.
The breaker is sized to match the wire and the load.
__________________
Yes I am a Pirate, 200 years too late. "Jimmy Buffett"
jbfan is offline   Reply With Quote
The Following User Says Thank You to jbfan For This Useful Post:
Jim Port (11-08-2012)
Old 11-08-2012, 05:46 PM   #10
Thread killer
 
Join Date: May 2011
Location: Southwestern Ontario, Canada
Posts: 304
Rewards Points: 268
Default

Help Needed Choosing 220v or 120v Tankless Water Heater and Proper Amperage


Why does it need to be tankless for a washing machine and kitchen sink?
__________________
You can have it good, fast or cheap. Pick two.
Canucker is offline   Reply With Quote
Old 11-08-2012, 05:55 PM   #11
Newbie
 
Join Date: Jun 2008
Posts: 26
Rewards Points: 25
Default

Help Needed Choosing 220v or 120v Tankless Water Heater and Proper Amperage


Quote:
Originally Posted by Canucker View Post
Why does it need to be tankless for a washing machine and kitchen sink?
Long story, but this is just 1 of 5 water heaters in the home and since it is only used sparingly, it seems tankless would make the perfect replacement and not wasteful. It looks like I will just order the 120v tankless. I am in a southern state with warm ground water so hopefully the 120v tankless will work.
wonderworm is offline   Reply With Quote
Old 11-08-2012, 06:01 PM   #12
Newbie
 
Join Date: Jun 2008
Posts: 26
Rewards Points: 25
Default

Help Needed Choosing 220v or 120v Tankless Water Heater and Proper Amperage


Quote:
Originally Posted by jbfan View Post
Most water heaters are 240, but small 6 to 10 gallon one can be 120. You can not tap into any line and just upgrade the breaker.
The breaker is sized to match the wire and the load.
Looks like the current tank is only 19gallons, not 40 as I thought. It has a single element and that's why it is only 120v.
wonderworm is offline   Reply With Quote
Old 11-08-2012, 06:09 PM   #13
JOATMON
 
ddawg16's Avatar
 
Join Date: Aug 2011
Location: S. California
Posts: 7,651
Rewards Points: 2,616
Default

Help Needed Choosing 220v or 120v Tankless Water Heater and Proper Amperage


Quote:
Originally Posted by wonderworm View Post
Long story, but this is just 1 of 5 water heaters in the home and since it is only used sparingly, it seems tankless would make the perfect replacement and not wasteful. It looks like I will just order the 120v tankless. I am in a southern state with warm ground water so hopefully the 120v tankless will work.
In that situation, tankless makes sense....but you need to determine what your real GPM requirement is...then go from there.
__________________
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 online now   Reply With Quote
Old 11-09-2012, 08:36 AM   #14
Member
 
Join Date: Jan 2009
Location: WV
Posts: 3,015
Rewards Points: 2,210
Default

Help Needed Choosing 220v or 120v Tankless Water Heater and Proper Amperage


Does your area have natural gas? Gas tankless heaters (I have one) are easier to deal with.

Advertisement

md2lgyk is offline   Reply With Quote
Reply


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
Tankless water heater to pre-heat incoming water matthet Plumbing 28 12-20-2011 09:11 AM
gas water heater recommendation please raylo32 Plumbing 2 08-17-2011 06:21 AM
DIY gas tankless water heater lofar Plumbing 42 12-19-2010 02:01 PM
Basement water heater "discharge line" proper draining ideas/options? ohman Plumbing 5 06-24-2009 02:22 AM
Tankless water heater proper pipe size? gante Plumbing 5 04-06-2009 03:28 PM




Top of Page | View New Posts