Upon arrival unit was at 20 psi and the pressure relief was dripping. This indicates the diaphragm of the pressure relief was going bad and allowing water to leak by. Drained pressure from the system and replaced the pressure relief. When the system was empty we found that the pressure gauge was stuck at 19 psi. After getting customer authorization we replaced the temp/pressure gauge. Filled system back up with water and bled all 3 zones. Started and tested the boiler. Had hot water coming back on all 3 zones. Unit is working properly. Unit was at 20ppm when leaving