The heat on the second floor of my home is blowing cold... its a 2 zone weil mclain hydro system... the st floor is hot... the second is cold what I have observed so far

1. the boiler control unit has a light blinking... limit

2. if I touch the pipe just below the circulating pump its very hot... just above the pump is warm... as I move away from the boiler a few feet the pipe is cold


Any ideas?. I took the liberty of putting a new circulating pump just in case... but didn't fix the problem

Low system water pressure is the place to look first. You need about 12 pounds for a 2 story.