In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
Im pretty sure it depends on the manufacturer. Not all have tappings in the same place.
The BTU ratings in most manufacturer literature I've seen is based on supplied water temp and designed delta T
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
"We see the world as WE are, not as IT is, because it is the "I" behind the EYE that does the seeing"