[SkagitAviator]

So I installed a 36k electrical tankless water heater as per instructions in the house. Used the correct breakers, the correct gauge wiring and it’s fully functional however when the water heater is in use all my LED bulbs flicker rapidly in my house. As you can imagine this is very annoying and my electrician is stumped 🤦🏽*♂🤷🏽*♂ Any help ?!? I changed some bulbs to standard bulbs (not led) but even those flicker a little.

 

[ddawg16]

The only way to know what the problem is, use a voltmeter and measure the voltage on both sides of you load center while the water heater is in operation.

And I would suggest doing this pretty quick.

If either leg drops below 105 Vac, you have some issues.

 

[joed]

36kw heater at 240 volts draws 150 amps. I would expect nothing less than blinking lights.
What size is you service?

 

[u3b3rg33k]

AFAIK those heaters are pretty simple and cycle elements on/off to maintain temp instead of using a faster PWM - no way around the source of the problem - maybe a tank heater? you could try the "non-dimmable" LED bulbs.

 

[dmxtothemax]

Have you measured the voltage at the led lights
When the heater is on and compared it to when it is off ?

 

[Jim Port]

You needed to add a second.service just for the tankless. The power company should have been told.you were adding so much new load. The transformer may be too small. Hard to believe your electrician has no clue as to the issue.

 

[SkagitAviator]

36kw heater at 240 volts draws 150 amps. I would expect nothing less than blinking lights.
What size is you service?

I have 200 amp service

 

[SkagitAviator]

You needed to add a second.service just for the tankless. The power company should have been told.you were adding so much new load. The transformer may be too small. Hard to believe your electrician has no clue as to the issue.

I will talk to the power company today about that thanks.

 

[supers05]

I have 200 amp service

It's too small. You probably won't be able to turn on your oven and stove top at the same time as the water heater. Hopefully your heating system isn't also electric.

Cheers!

 

[supers05]

AFAIK those heaters are pretty simple and cycle elements on/off to maintain temp instead of using a faster PWM - no way around the source of the problem - maybe a tank heater? you could try the "non-dimmable" LED bulbs.

It depends on the model. The better versions use faster PWM instead of multiple elements and contactors.

Cheers!

 

[carmusic]

the poco xfmr is probably 25kva for multiple house so, it is probably overloaded too much

 

[Bob Sanders]

It's too small. You probably won't be able to turn on your oven and stove top at the same time as the water heater. Hopefully your heating system isn't also electric.

Cheers!

Yeah... With the hot water running at 150 amps, there is not a lot left over to run other things.


I looked at electric tankless a while back. It sure is a cool idea, but decided it just wasn't worth it in the end. Too many variables involved to guaranty a dependable system. Just the change in city water temps between Summer and Winter is enough to screw up your day.


My advise... junk it and install a conventional tank.

 

[Bob Sanders]

the poco xfmr is probably 25kva for multiple house so, it is probably overloaded too much

LOL!
The neighbors are probably wondering why THEIR lights are flickering.

 

[chandler48]

I have a propane tankless and would never have considered an electric. Face it, a tank water heater runs off 30 amps and provides ample hot water. Jumping the electrical usage to 150 amps on a 200 amp panel does not compute. We save a great deal comparing propane cost to original electrical cost. Just not sure of the logic of an electric tankless.

 

[georgemcq]

Is it too late to get your money back? This installation will never work out in a positive way. The only way for tankless is NG or propane.