Using a Voltage Regulator to reduce power to a water heater

[Haysdb]

This is an idea ChatGPT came up with, but I can’t find any YouTube videos or forum posts to confirm that this will actually work. What I HAVE seen is posts from people using a dimmer switch to do this. Well, that’s what a voltage regulator is, a sort of dimmer switch.

Let me start at the beginning with what I’m trying to accomplish:

1. I want to control when my water heater turns on. I have an idea to use a Shelly Pro 1PM to set a schedule for when the water heater will be allowed to come on. I’ll turn it on during peak solar production, like right around noon, and again an hour or so before everyone gets up and starts taking showers. That’ll help me burn off any additional battery power still remaining.
2. This is totally unnecessary but I’d like to not see the scary 3kw spike when the water heater comes on and runs for 15 minutes. There’s no hurry to heat up the water, so why not let it run for an hour at lower power? I’d see an hour long “hump” a couple of times a day instead of a 3000 watt spike.

So, my idea is to put the Shelly and a 25A voltage regulator in series prior to the water heater. It’s a simple resistive load, so why wouldn’t a lower voltage accomplish what I want? Just turn down the “dimmer” to 160v or whatever?

Why won’t this work? Why should I definitely NOT do this?

 

[v_green57]

Because it's possible you might still see the "spike" as the "dimmer" figures out what it needs to do. Cheap dimmers don't "dim" by lowering the voltage, per se. They dim by chopping part of the AC waveform out so the effective power is reduced.

Better to change the elements to something lower and avoid it altogether. No need to overcomplicate things with additional components that add more points of failure.

 

[sumpower]

Lead acid batteries or Lithium iron phosphate? This is concerning load draw off of the battery. If lithium it doesn't make much difference.
If lead acid the longer time interval will extend your battery life.

I have a preheat water heater with approximately 1700 watt elements, on as early in the morning as possible. Which varies through out the year.

By having the pre heat tank and a regular tank the problem of controls complexity was eliminated.

 

[Haysdb]

LFP, and you’re absolutely right that it doesn’t make any difference. This is just me wanting to do something because I want it and not because it makes any damn sense. It bugs me that I have no control over it, over when it comes on or much power it uses. I’m retired and I literally have nothing better to do than obsess over this kind of thing.

The only question I have is: will it work?

 

[Haysdb]

In the spirit of “the Russians used a pencil”, I didn’t realize that a lower power heating elements costs $15 and is easy to replace. That’s less than the cost of the voltage regulator, which would work, it’s just an over engineered solution. Claude sums up the situation nicely…