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MVR3 · Jan 28, 2010, 07:14 PM

I have a commercial building. The second floor has 15 rooms, my problem is that I have 3 rooms that have a problem. The 3rd room only has half the heat in it the beging of the rm radiators are hot the second part is ice cold, the 4th rm has half heat the beging is ice cold and the second part is red hot.
I have bled the system and no air comes out, I kept on bleeding the system until I got red hot water out the radiator, after 5 minutes the water turned ice cold again.

hvac1000 · Jan 28, 2010, 07:28 PM

You will need to check the boiler water pressure or altitude gauge to make sure enough pressure is available for the system to operate. Just because the pump runs does not mean that the hot water will move to the second floor unless the pressure is available at the boiler. Since I know nothing about the system you are working on and since many systems are different I would start at 12 psi and move up to 16 psi maximum. A commercial building is not like a house since the different floor/ceiling levels are different in height (altitude) so the amount of pressure necessary can vary.

One other possibility is the pump or pump impeller. If it is damaged or worn it might not move the water very well.

Last but not least is the water control system. Many times different rooms will have a zone valve that allows for thermostatic control of the space. If the zone is not working in a specific room this could also cause the room not to heat.

MVR3 · Jan 28, 2010, 08:20 PM

First things first thanks for the reply. All the pressures are good, the pump is fine. It is just sections in the 3 rooms that aren't getting heat. The beging of the run is nice and hot, and the end of the run is nice and hot. It is just the middle rooms that loose hest in half of the rooms. I even had a a/c and heating company that couldn't figure this out. Thanks again

hvac1000 · Jan 28, 2010, 08:56 PM

Those are the kinds of problems I used to like to work on when I was a young man since it is much more interesting than the every day stuff. The problem is you have to be there to fix it since you cannot see it all in a post. Good luck.