Here's an interesting device, for 'thought' or possible real experiments
http://www.spiraxsarco.com/pdfs/TI/p023_59.pdf
Given low-quality steam (steam mixed with water and air) this device
separates it into dry steam, air and water.
For the ecat, there will be little or no air after it's run for a while.
One could just collect the water, weigh it, and subtract it from the
heat equation.
(Keep the water-heating part, but subtract the evaporation enthalpy).
If the mini-ecat operates at 7L/hr 0 bar Gauge, their smallest model
looks as if it might work.
The spirax site has a lot of interesting documentation, particularly
http://www.spiraxsarco.com/resources/steam-engineering-tutorials/steam-engineering-principles-and-heat-transfer/what-is-steam.asp
(scroll down to "dryness" section)
Steam produced in any shell-type boiler (see Block 3), where the heat
is supplied only to the water and where the steam remains in contact
with the water surface, may typically contain around 5% water by mass.
If the water content of the steam is 5% by mass, then the steam is
said to be 95% dry and has a dryness fraction of 0.95.
