Sorry... I left out the most important part:

Thank you for taking the time to read my mini-PHd thesis and thank you in advance for any help you can give.

Update: We have narrowed it down to the heater:

System unplugged: Wheel on meter takes 24 counts to turn
System plugged in, but heater turned off: 24 counts
System plugged in, heater on: 4.5 counts

Tomorrow, we will start checking to make sure the electrician wired it all correctly and then start looking for where the issue is... any ideas are still very appreciated.

Kate

It seems you answered your own question. Nothing appears to be wrong. That heater sucks up power. It probably cycles on & off (I hope!) and therefore will not be "on" at least some of the time.
I have an electric HW heater with a 5500 watt lower element. It's on a separate meter, which really flies when the lower element is on!

Make sure the line voltage is coming from 2 seperate legs. If the entire power is only on one leg it can have an affect on the meter.

"Make sure the line voltage is coming from 2 seperate legs. If the entire power is only on one leg it can have an affect on the meter."

Say what?

The power for the heater would be 1/4th if it was connected across 120 V.

Meters are not affected by load imbalance between the two 120 V legs.

"It seems you answered your own question. Nothing appears to be wrong. That heater sucks up power. It probably cycles on & off (I hope!) and therefore will not be "on" at least some of the time.
I have an electric HW heater with a 5500 watt lower element. It's on a separate meter, which really flies when the lower element is on!"
-----

I know that the heater draws a lot, compared to other things, but the calculations I did that show that we are using almost twice what we 'should' be using assumed that the heater was on 24 hours a day, everyday (which it is not).

You indicate that you have a 5500 W heater also... I am assuming you do not have over a $700 electric bill each month, which is what we will have if I keep it on. lol

We are going to try changing the element first.

If the system is a 220 and the both breakers are on the same 110 vac input it can have an effect on the meter.

If the load is 240v and you try to power it from two breakers on the same leg of the mains, it most certainly will "affect" the meter - because the load won't receive any power!

Kate, you can't really read the heat

Oops, sorry, let's try that again.

If the load is 240v and you try to power it from two breakers on the same leg of the mains, it most certainly will "affect" the meter - because the load won't receive any power!

Kate, you can't really read the heat er's actual load from the hoome's kWh meter readings. There are too many other loads mucking up the numbers.

I think you need to put an ammeter right on that heeter. You could also measure the element's resistance with an ohmmeter and calculate the current with Ohm's Law. Ohm's Law : power = voltage squared, divided by resistance in Ohms.

Don't just go changing parts willy-nilly; do some diagnostic work first. A cheap multimeter from the local harware store will serve you well and probably svave you money in the long run.

All that said, I'm concered about your installation there. You say this machine is connected to a 30 amp supply. For sustained loads that supply should be limited to 24 amps, or 5760 watts. The 5.5kW heatr alone, even at rated power, would just about max out that circuit.

Motor loads are different and I'm not an expert on them, so I'll defer to others if they say it's OK. But it seems to me that if the nameplate rating on that motor is really 5hp, it shouldn't be connected to a 30 amp supply along with a 5.5kW heatr. Anybody else here want to correct or amplify this?

"You could also measure the element's resistance with an ohmmeter and calculate the current with Ohm's Law. Ohm's Law : power = voltage squared, divided by resistance in Ohms."

Except that heaters, like light bulbs, change there resistance between cold and hot.

As the element heats up its resistance rises, and by enough to affect long term power dissipation.

The heater will NOT stay on all the time either.
It has a thermostat controlling the water temperature.

> As the element heats up its resistance rises, and
> by enough to affect long term power dissipation.

True - but maybe not very significant for this situation. For an immersion element, the temperature of the nichrome wire buried inside is going to stay pretty close to the water temp, no?

From 20 deg C to 90 deg C, the resistance of nichrome wire increases 1.7%. Suppose the rated power of the element is 4800 watts and it operates at 240v. The resistance of the element at operating temperature is 12 ohms. Let's assume the operating temp is 90 deg C, a little high for water you're going to swiom in, but it makes things easy. The resistance at 20 deg C is 12/1.017, or 11.8 ohms. Close enough. (Actually, that 1.7% is probably pretty close to the inaccuracy of a cheap hardwware store multimeter.)

So, in this case I think a resistance measurement will probably serve as an acceptable "go / no-go" test.

That said, a cheap clip-on ammeter would probably be even less accurate, and would cost more, but might be easier to use.

My question is, what else do you have in this house that is sucking up power? Heated floors?

"For an immersion element, the temperature of the nichrome wire buried inside is going to stay pretty close to the water temp, no?"

Not even close.

The element is packed with ceramic to spread the heat out for a reason.