@SSM
If the answer is yes, and the pressure in the system is less than 1psi per 2.31ft, then it's a problem
Ex, 2 story house, height of second floor, in floor heating is 11ft.
11ft / 2.31 = you need 5psi minimum.
Or 21ft (3rd floor), 21 / 2.31 = 10psi minimum.
Assuming the gauge is not faulty
Furthermore, you may have air vents that are airlocked, these need to be bled out. (Same as your car radiator loop, highest points may get airlocked)
Manual air vent = open till there's no air, if your unlucky, the gasket is gone and it will not re seal
Auto air vent = probably failed, or the 1/4cap has been tightened, loosen 1 turn, wait till it stops hissing, close back up
Or you have a couple of rats that made it into your closed loop heating system
