# 208v 3 phase water heater on 120v/240v service



## drspec (Sep 29, 2012)

An apatment complex called me to wire up a water heater. 
What they have is a 3 phase 208v water heater that can be converted to 208v single phase, but is not convertible to 240v.

Is there another option for this?


----------



## nolabama (Oct 3, 2007)

Yes , have the cheap a$$ property folks get the correct heater and bill them for being stupid.

And what is 208 single phase?


----------



## drspec (Sep 29, 2012)

using 2 legs of a 3 phase system?


----------



## big2bird (Oct 1, 2012)

drspec said:


> An apatment complex called me to wire up a water heater.
> What they have is a 3 phase 208v water heater that can be converted to 208v single phase, but is not convertible to 240v.
> 
> Is there another option for this?



You "could" use a buck/boost, or as stated, just buy the correct unit for the app.
You could also replace the elements, but that would cost as much as the heater itself.


----------



## drspec (Sep 29, 2012)

I think they are going to install 2 - 240v water heaters in lieu of this one.

The funny thing is they bought this unit about 4 years ago and it has never been hooked up. Unit cost at least $3000 then.

I was just trying to see if there was another option that I could recommend for them. 
This job is going to require a panel replacement at the minimum and possible a service upgrade as well.


----------



## bobelectric (Feb 24, 2007)

Change the elements to 240 volt.


----------



## micromind (Aug 11, 2007)

A buck-boost transformer is certainly an option.


----------



## Vintage Sounds (Oct 23, 2009)

If they're going to need a service upgrade anyway how do they feel about going 3 phase?


----------



## hardworkingstiff (Jan 22, 2007)

nolabama said:


> And what is 208 single phase?


IMO, a suck azz system.


----------



## hardworkingstiff (Jan 22, 2007)

big2bird said:


> It will work as is at single phase. It will just lower the BTU output, and take longer to heat up.


Are you talking about wiring the 208V rated elements to 120V ?


----------



## sbrn33 (Mar 15, 2007)

hardworkingstiff said:


> IMO, a suck azz system.


120/208 volt system is the ****. Especially for an apartment or condo building.


----------



## big2bird (Oct 1, 2012)

hardworkingstiff said:


> Are you talking about wiring the 208V rated elements to 120V ?


Nope. Dyxlexia kicked in. :laughing: I was thinking backwards. Those elements won't last, as they will draw more than their rated wattage at a higher impressed voltage. 
Change em, or buck em.


----------



## Dennis Alwon (May 9, 2009)

Well besides voiding the listing I doubt that anything would come of hooking 240V to a 208 element other than higher wattage from the element-- perhaps permature death. I think the best option is to change the elements but I don't know why they don't make these rated in 208 or 240V seems ridiculous. Are you sure they are not dual rated


----------



## sbrn33 (Mar 15, 2007)

Wouldn't they last forever? just not get as hot.


----------



## hardworkingstiff (Jan 22, 2007)

Dennis Alwon said:


> Well besides voiding the listing I doubt that anything would come of hooking 240V to a 208 element other than higher wattage from the element-- perhaps permature death. I think the best option is to change the elements but I don't know why they don't make these rated in 208 or 240V seems ridiculous. Are you sure they are not dual rated


I was thinking the same thing. Heck, the elements are immersed in water so they won't get overheated, and the current will only go up by 15% and the water will heat faster.


----------



## Dennis Alwon (May 9, 2009)

sbrn33 said:


> Wouldn't they last forever? just not get as hot.


No they would get hotter and the element may not be made for that. Remember higher voltage with resistant heat means a hotter element- more wattage not less. I doubt it will hurt the element


----------



## sbrn33 (Mar 15, 2007)

Oh duh, I was thinking 240 volt heater on 208. To much thread jumping.


----------



## drspec (Sep 29, 2012)

I called the manufacturer as the nameplate had it listed as 208 3 phase or 208 single phase. They said those were the only configurations for that model, but inside there were jumper connections listed 120, 240, 277 and 208 I believe. I wish I could post pictures on here to show this.


----------



## Dennis Alwon (May 9, 2009)

drspec;835708 but inside there were jumper connections listed 120 said:


> That does not sound correct. What is the brand and model number


----------



## big2bird (Oct 1, 2012)

drspec said:


> I called the manufacturer as the nameplate had it listed as 208 3 phase or 208 single phase. They said those were the only configurations for that model, but inside there were jumper connections listed 120, 240, 277 and 208 I believe. I wish I could post pictures on here to show this.


How about a model #?


----------



## drspec (Sep 29, 2012)

Rheem ES85-18-G


----------



## Dennis Alwon (May 9, 2009)

drspec said:


> Rheem ES85-18-G


I see that at graingers as a 480V heater, 18000 watt and 85 gal.

http://www.grainger.com/Grainger/RH...6&srccode=cii_16079562&cpncode=32-175198985-2


----------



## big2bird (Oct 1, 2012)

drspec said:


> Rheem ES85-18-G


http://mexico.rheem.com/content/res...co/CommHvyDtyElec_6kw-81kw_RR102CE-1rev11.pdf

Looks like it is multi tapped to me.


----------



## Dennis Alwon (May 9, 2009)

big2bird said:


> http://mexico.rheem.com/content/res...co/CommHvyDtyElec_6kw-81kw_RR102CE-1rev11.pdf
> 
> Looks like it is multi tapped to me.


Not multi tap but available in those voltages.


----------



## big2bird (Oct 1, 2012)

Dennis Alwon said:


> Not multi tap but available in those voltages.


"Internal 120v control transformer has unique taps for 208,240v,277v, and 480v"

I can't find a tap change drawing, But I tend to lean towards "one size fits all."


----------



## big2bird (Oct 1, 2012)

drspec said:


> I called the manufacturer as the nameplate had it listed as 208 3 phase or 208 single phase. They said those were the only configurations for that model, but inside there were jumper connections listed 120, 240, 277 and 208 I believe. I wish I could post pictures on here to show this.


See what you can find. Owner/installation manual, jumper door drawing, something.


----------



## drspec (Sep 29, 2012)

I have the diagram and instructions for changing from 208 3 phase to 208 single phase.
Rheem tech support said those were the only settings for that model. Not sure why grainger lists it at 480 and 240. The nameplate only had ratings for 208.
Even IF it could be converted, there's no rating for amps for 240. At 208 single phase this unit is 87 amps.


----------



## Dennis Alwon (May 9, 2009)

drspec said:


> I have the diagram and instructions for changing from 208 3 phase to 208 single phase.
> Rheem tech support said those were the only settings for that model. Not sure why grainger lists it at 480 and 240. The nameplate only had ratings for 208.
> Even IF it could be converted, there's no rating for amps for 240. At 208 single phase this unit is 87 amps.


calculate it


----------



## Dennis Alwon (May 9, 2009)

if the unit is rated 87 amps at 208 then it has a resistance of 2.4 ohms. R= V/I

Thus Watts = V^2 */R = 240*240/2.4= 24000 watts. 24000 watts /240V = 100 amps

Now multiply by 1.25 for continuous load


----------



## big2bird (Oct 1, 2012)

drspec said:


> I have the diagram and instructions for changing from 208 3 phase to 208 single phase.
> Rheem tech support said those were the only settings for that model. Not sure why grainger lists it at 480 and 240. The nameplate only had ratings for 208.
> Even IF it could be converted, there's no rating for amps for 240. At 208 single phase this unit is 87 amps.


Hook it up 1 phase, and buy a 3KVA 32V buck. Done deal.


----------



## drspec (Sep 29, 2012)

I come from a residential background. While I have experience with 3 phase, I have never hooked up a buck, so I am not familiar with them.
They need prices and options by tomorrow for their budget. 
Price of the transformer? How labor intensive are they?


----------



## big2bird (Oct 1, 2012)

drspec said:


> I come from a residential background. While I have experience with 3 phase, I have never hooked up a buck, so I am not familiar with them.
> They need prices and options by tomorrow for their budget.
> Price of the transformer? How labor intensive are they?


Call in the morning. I have not a clue.


----------



## hardworkingstiff (Jan 22, 2007)

drspec said:


> I come from a residential background. While I have experience with 3 phase, I have never hooked up a buck, so I am not familiar with them.
> They need prices and options by tomorrow for their budget.
> Price of the transformer? How labor intensive are they?


My guess would be about $300-$400 or so for the transformer and $50-$100 in wiring plus mounting hardware. 

If you can read a schematic OK, you should be able to hook it up in less than an hour, you may need some time for mounting plus some mounting hardware dollars.

But remember, this advice is worth what you are paying for it. :laughing:
You need to make the call for pricing.


Edit: Check this out.
http://www.buckboostcalculator.com/index.cfm


----------



## hardworkingstiff (Jan 22, 2007)

bobelectric said:


> Change the elements to 240 volt.


I think this is the best solution. 6 elements (I bet they aren't more than $25 each) for less than $200 and some labor.


----------



## chicken steve (Mar 22, 2011)

are these factory taps the configuration of these elements? ~CS~


----------



## etb (Sep 8, 2010)

big2bird said:


> "Internal 120v control transformer has unique taps for 208,240v,277v, and 480v"
> 
> I can't find a tap change drawing, But I tend to lean towards "one size fits all."


You can't find one because there isn't one: the taps are for the xfmr.



Dennis Alwon said:


> calculate it


I agree with your calc, but a simpler way is
87 * (240/208) = 100 A



hardworkingstiff said:


> I think this is the best solution. 6 elements (I bet they aren't more than $25 each) for less than $200 and some labor.


I agree, but would need to check with plumbing house on thread or bolt size of elements. This model has 6, but 240V elements for this model are 6kw, so may only need three. They do make 240V 3kw but may not fit the hole. If not, plug the other three holes or take the screws out of the terminals. And leave a note for the next poor sap.


----------

