I am looking at adding a tankless water heater but I don't have enough spaces in my breaker box for the breaker requirements of the heater. It is asking for 3 double pole 40 amp breakers and I am thinking about adding in a sub panel for the water heater. I was wondering if this is ok and what size breaker do I need to install for the sub panel. If this helps anyone answer my questions or give me advice I am looking at a eco smart 27. it requires 3 40 amp double breakers and im new to electrical work and don't know much I am having a electrian come out and do the work so it is done right and so I don't kill myself. I do know that the eco smart 27 has 3 heating elements in it and thasts the reason for the 3 breakers.
Water – tankless water heater
heaterinstallationsubpanelwater
Related Solutions
No, the 100 Amp breaker feeding the sub-panel is not the reason for the water heater not working.
Has the heater ever made hot water, has this started recently?
The 100 Amp feed is wrong for other reasons
Others will likely talk about 'code violations,'but without knowing when and where your system was installed, those are just guesses at this time.
If the lights are on, and the buttons and dials work correctly - we will take a leap of faith and say the electronics that are not directly connected to the heat elements are working.
I am also going to suppose that the heater is wired correctly.
Also that the hot and cold water pipes are connected to the rest of the plumbing correctly, and that the needed valves are open.
So that when you turn on the water faucet in a sink the cold water to the house flows into the cold water port on the water heater, then flows out of the hot port on the heater, and comes out the sink.
This leaves at least:
power wiring to and from the connection points for the heater
flow sensor - 1
temperature sensor cold side - 1
temperature sensor hot side - 1
heating elements - 3
high temperature cut off switch - 3
scr used to control the cycling of the heating element - 3
If only 1 set of scr, high temp, and heating element work, then some hot water will be produced.
--- I will work on this some more, within the next few hours.
Electronics that are connected to the heating elements
10 AWG wire.
THWN type if in conduit.
NM type if using plastic sheathed multiconductor cable. 10 AWG is typically orange. 10/3 if it needs neutral, otherwise 10/2 and re-mark the white wire as a "hot" by wrapping it with black tape.
Many 240V heaters do not need a neutral. But if you include neutral, you may thank yourself later, because it'll give you the most versatility in terms of other things you might plug in there in the future.
You can also look at the plug for your heater and see what it requires. Even if it doesn't require a neutral, you are perfectly welcome to run a neutral, and simply cap it off in the electrical box for future use.
You must choose. You are not allowed to put 2 receptacles on a 30A supply cable in this type of installation. The NEMA 10-30 is bad news and should be avoided, anything that requires it, you should replace it with 14-30.
Best Answer
This heater alone required 113 Amps with really heavy hot water usage. So first you need an electrician to look at your house and your electrical panel/s to see if you have that much power available. The sub-panel idea is good if you have the available power. The sub-panel would need a rating of at least 125-Amps. You need to have newer and quality service equipment. Otherwise this type of a load could really raise havoc.