heat exchanger problem

instructor

I have a heatexchanger at a job that can only produce 160 degree water. Both high and low load steam valves are wide open I have 4psi inlet and 4psi @ the blowoff beforer the ft trap. There is a 10 degree diff over hxchanger with both circ pumps running if 1 circ is running get about 30 diff and can produce 180 supply temp but not enough flow through system. System was installed 1980s i am thinking the xchanger could be limed there has been no water treatment ever on this system.

JK_3

Wow

I dont Know If Yours will be the same but just this heating season I just had a similar call. after about an hour of racking my brain I began to feel mabye it was not getting full fire. As I  started to disassemble the gas pipe to proform a pressure test I found the screen In the valve loaded with slime. We beleive that it may have come from the gas company's recent work on the street mains. Cleaned out the screen and all is well. Just a thought that might help.