Welcome! Here are the website rules, as well as some tips for using this forum.
whats best practice on bleeding unitheaters
3 story dormitory. Heat with hot water in winter in summer cool with cold water. Single coil in the unit heater. Each room has pneumatic thermostat. When we switched to cooling this year a lot of air got introduced in to the system. The usual procedure here was to just go to each unit and bleed the air out while the system is running. Well its not working very good. To much air. Ive been to each room (about 40) 4-5 times getting the air out only to come back and do it again. Ive re pressurized the system 4-5 times also. Finally fed up I shut the circulator down pressurized to about 40lbs static and with my 5 gal bucket I have been bleeding. I'm running a lot of glycol out on each and when the bucket is full going back down and pumping it back in. 2 times around with that. About 15 gal of glycol put back in. Still getting some air but better. When I left for lunch all units were 55-60 coils. Is the better procedure turning off the circulator. When I do that the other floors will stop cooling but not that long and building is not occupied anyway.
coming to you from warm and sunny ND