On hot water side the pressure is very low. Hot water is hot, but not presser behind it. The boiler has been drained and I don't seen to see any filter to clean. The psi on the boiler gauge is 20psi and the expansion tank at 18psi. Any ideas? Thank you

The expansion tank is on the return side of the water pump so the ressure here will be the same as the inlet water pump pressure, the gage on the boiler is the discharge side of the pump and will be higher,(25 to 35 lbs.) you may have air in the system or a faulty pump, try bleeding the air out of the boiler and restarting the pump. Good luck, Mike

On hot water side the pressure is very low. Hot water is hot, but not presser behind it. The boiler has been drained and I don't seen to see any filter to clean. The psi on the boiler gauge is 20psi and the expansion tank at 18psi. Any ideas?? Thank you
Thanks for the info... I don't believe I have air in the system. I do have a Taco circulator cartridge. I would assume this to be the circulator pump? And could this be the issue.? Thanks Stan

If you have 20 PSI in the boiler then flow should be no problem unless the circulating pump is defective.