Tankless water heater KW

I have a Rheem 13kw Tank less water heater on one side of the house for spare bedrooms and bath. I recently added a Jnod 18KW Tank less on the other side, master bath and kitchen. Now Im confused.

I open the bath tub faucet on each side one at a time.
I have a wireless Kilowatt meter on the master breaker box incoming 200A lines. When I turn on the Rheem I read a 11KW rise. Current measured at the breaker with clamp on (single 220v breaker) I read 55A and 57A = 113A
When the Jnod is on I read a 10.3 kw rise. At the breaker (double 220v) I get 39A + 37A + 20A + 21A = 117A. The measured voltage = 240V. The numbers do not add up.

Could the Jnod be mislabeled and only 13KW

 

Not sure where you are taking the 4 readings on the the Jnod, you should be clamping around supply conductors not each circuit conductor if that makes sense, don't add the loads,also were the water temps equal?
Geo.

 

There are 2 220v breakers, I read each of the 4 incoming lines but not the 2 grounds. What should I read both the white and black lines together for each breaker? So only 2 readings?

 

What you did seems correct except each reading should be : circuit 1 approx. 40 amps. Blk,White
Circuit 2 approx. 20 amps. Blk. White
You don't add the legs up. So what you really have is. 40X240 = 9.6KW. 20X240 = 4.8 KW
there a 2 circuits in the Jnod
Hope this makes sense
Geo

 

So what your saying is what I thought The Jnod is almost the same as the Rheem? Around 12.3KW. For the Rheem and and 14.2 for the Jnod. Not near 18kv.
BYW both wrere wide open, but the Jnod deliverers more flow.

 

That seem's to be the case ,maybe the Chinese KW is different!I just noticed in you first post you read 10.3 KW on the Jnod, could that be that only 1 element was energized at that point?
Post any spec's you have on the heater or at least Model# I would be curious how it operates.

Geo

 

I was just looking at their add again today and saw it shows 3 triacs, mine only has 2. It originally listed as a 18kw model and the display showed, in temp, out temp and flow rate as well as a heater on icon on the display, The one I got only shows the in and out temp. Both showed C or F and a set temp. The highest set temp is 125F
Ar first when I complained they sent a new display board, which didn't help, then 5 emails later the said they improved it and it now only shows the in and out temp. They had asked me to lower the input water flow which I did and it didn't help. I also had to remove all the low flow washers from my faucets or I didn't get enough flow to start it.
It does appear to fill the tub with hot enough water but the Rheem does not, the Rheem is also a lower flow rate and I also had to remove the washers. Before these I had a Eemax 18kva but was always changing the elements. I ended up buying nichrome wire and buying my own. There problem is the screws that attach the wire to the terminal would rust and let go of the wire. I also had the repair both boards in the Rheem, they use a read relay to sense water movement (must be a magnet inside the chamber). A resistor also burnt out in one. A friend had the same model with similar problems, 4 new elements and one board in 2 years. He junked his first. I junked my 3 weeks ago. I originally had one I bought in Berlin in the 80's which lasted until 2006.
Here is pictures of mine and what the show on the web page.