Tankless water heater

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hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
Got a call today from one of the boss’s friends today. He owns a hotel converted to low income apartments. He wanted me to come out and look at one of the apartments he had a contractor remodel. They changed the tank type water heater to a tankless. Anyway, he was unhappy with their work and fired them after the first apartment. I asked him what kind and size of tankless did they install? He said he thought it was a 17 kw. I told him that could be a problem, the apartments have only a 100 amp single phase service, and are totally electric! Had him send me a picture of the panel, and it confirmed what I thought! He asked what we needed to do to fix it? Oh, just change out the entire service and meter pack, replace every panel and feeder. Nothing major, LOL! (Two story, 40 units)
 

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I think he already bought all of the tankless ones. May just turn off one circuit and see how hot it gets. Wouldn’t want to be taking a shower and somebody turns a sink on! LOL !
 
hillbilly1 said:
I think he already bought all of the tankless ones. May just turn off one circuit and see how hot it gets. Wouldn’t want to be taking a shower and somebody turns a sink on! LOL !
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A good tankless will reduce the delivered volume to maintain the set temperature.
You will still get a surprise in the shower, but if you set the tankless temperature low enough that you don't add much cold you should be just fine.
For dishwashing let the heater in the dishwasher bring the temperature up.
I set my tankless for 125 in the summer and 130 in the winter and with a very long run of pipe to the shower it works out just right.
 
>I think he already bought all of the tankless ones.
Ebay, at least get some money back.

Did the one unit and new service get inspected?
 
hillbilly1 said:
No new service, no permit, the contractor slapped two 40 amp breakers in there, and called it a day. Still 100 amp!
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But, but... if the panel has empty space then it must have the capacity for any load. Kind of like a checking account, if you have checks there must be plenty of money.
 
I have no sorrow for people like this. Especially the ones that consulted you and then did so anyway.
 
mbrooke said:
What is the main like? How many amps?

Given how overkill NEC load calcs are, this just might work.
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Are you saying ignore the NRC load calcs and go by gut feeling. I wonder how well that will go over with the Building dept or Insurance when things start to melt.
 
I ran a quick calc and I get 125 amp min right on the nose, IMHO that is too close to the limit of a 125 amp system.
Given my experience there will be future issues.
 
?Are you sure it is 17kW? Also, does the apartment have 240 volts, or is it 208?
 
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