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Need Help Confirming Electric Service for Tankless Waterheater

Need Help Confirming Electric Service for Tankless Waterheater

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  #1  
Old 03-07-18, 05:58 PM
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Need Help Confirming Electric Service for Tankless Waterheater

I'm hoping to get help confirming the service I have in my apartment unit. I'm investigating if a tankless waterheater would be feasible for my situation.

The below link has the pictures of the panel in my apartment and the main breaker in the electrical room. It seems to indicate that I have 150amps, 208v...but I could be wrong.


https://imgur.com/a/hONgM


I'm located in NJ; 3 story building; 1 bedroom; approx 700 sq ft. The building has only electric and NO gas. I'm aware that electric tankless waterheaters are generally not recommended, but still want to look into it. My main reason to switch to tankless would be to get some extra closet space.

Thanks
 
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Old 03-07-18, 06:56 PM
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A lot more information is needed as a load calculation should be done to figure out what the current loads are on the panel. If you have electric heat you might be maxed out already.

Also 208v vs. 240v makes a difference in total power (watts/volt-amps) that the panel can supply as well as the size/type of water heater you should get.

See similar conversation: https://www.doityourself.com/forum/e...r-heaters.html
 

Last edited by Astuff; 03-07-18 at 09:41 PM. Reason: Saw other pics. See 150a disconnect.
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Old 03-07-18, 08:45 PM
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Welcome to the forums.

I couldn't read any amperage off your main breaker at the meter.

Pretty heavily loaded.
50A range
40A heat pump/electric heat
30A A/C condensor.
30A electric water heater ?
 
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Old 03-08-18, 08:07 AM
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Thanks for the replies. I'll do some readings with my clamp meter to determine the current load.

Beyond that, I want to make sure I confirm the max service I get to my apartment. The electric tankless unit I looked at says it recommends 150amp minimum. It also details the difference in temperature rise possibilities for 240v vs 208v...so I'd like to confirm that as well.

My apartment is electric only: Stove/Range, Heat Pump, A/C condensor, tank water heater, etc. I don't have a washer/dryer though.
 
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Old 03-08-18, 08:58 AM
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It looks like a small 150 stamped on the breaker handle which probably means it's a 150A service, but it would also help to know what gauge wire runs from the building distribution panel to your panel.

The calculation you need to do to determine service capacity is called a "demand load calculation". The amp meter ratings are not considered in this. Gut feeling on this one is that you do not have capacity for a tankless electric water heater given the load of the other electrical appliances. We can help with the calculation if you'd like to. It would also help to know which tankless heaters you're looking at.

Often when we install tankless electric heaters it requires at least 200A service or a "residential 400" which allocates 200A for the house and 150A for the tankless.
 
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Old 03-08-18, 10:34 AM
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You are correct.... I missed that.

Name:  150.jpg
Views: 209
Size:  34.6 KB
 
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Old 03-09-18, 05:17 AM
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PhilA - just a question before you go much further with this tankless hot water heater.
You mention "apartment". In this case I would assume that you mean you "rent" this apartment.
If so have you received written authorization from the owner/landlord of this building to install this heater or in fact any authorization stating that any changes at ALL may be made to the electrical system? If not, I would highly suggest you do so due to major possible liability issues. And a "verbal" - "yup, no problem, you can put one in at your expense" answer from the landlord is not sufficient. Written is the best policy for protection. Be absolutely sure that the electrician/company etc is fully insured, licensed etc (what ever NJ requires) and that the installation is inspected and keep all documentation for possible future needs.
 
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Old 04-07-18, 12:13 PM
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It looks like a small 150 stamped on the breaker handle which probably means it's a 150A service, but it would also help to know what gauge wire runs from the building distribution panel to your panel.
Any suggestions on how to measure this?

This is a link to the inside of my panel...
https://i.imgur.com/COcFoac.jpg


The calculation you need to do to determine service capacity is called a "demand load calculation". The amp meter ratings are not considered in this. Gut feeling on this one is that you do not have capacity for a tankless electric water heater given the load of the other electrical appliances. We can help with the calculation if you'd like to. It would also help to know which tankless heaters you're looking at.
Would love to get help with a demand load calc.

I'm looking at the Stiebel Eltron Tempra 24 Plus. This is the spec sheet.
http://www.stiebel-eltron-usa.com/si...ecs-tempra.pdf


PhilA - just a question before you go much further with this tankless hot water heater.
You mention "apartment". In this case I would assume that you mean you "rent" this apartment.
I own the apartment
 
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Old 04-07-18, 03:29 PM
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I own the apartment

You my own the apartment but you do not own the building or the service equipment for the building. Before adding that much load (88amps) to the building service I would recommend confirming that it is OK with the building owner(s)
 
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Old 04-07-18, 09:19 PM
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A load demand calculation isn't difficult.

It requires you to obtain the wattage or amperage from all high current devices.
Electric range.
Electric dryer.
Air conditioner. Central or window.
The water heater is known.
Electric heating.
 
  #11  
Old 04-08-18, 04:53 AM
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PhilA - Here is an example of a basic load calculation form for a single family home. You may find more advanced ones on the Net but basically the same concept.

I don't think there will be much of a difference between the single family one and an apartment unit. It still covers the electrical for your specific home/unit.

Again, this is to show you what it looks like and what information is needed to determine your load demands.
 
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Old 04-13-18, 02:12 PM
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ibpooks had suggested to measure what gauge wire runs from the building distribution panel to my panel. Any recommendations on how to do this?
 
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Old 04-13-18, 04:21 PM
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Measuring is pointless as insulation types will vary in thickness. The wires should have a marking along the insulation indicating the size of the wire.
 
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Old 04-14-18, 06:39 AM
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The trouble is the calculation will affect the building service size also. More than one apartment needs to be calculated . The additional load may mean the building service is now too small.
 
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