One zone not getting hot - air locked?


Old 09-26-16, 07:07 PM
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One zone not getting hot - air locked?

I've attached a detailed picture. Basically the hot water drastically loses heat at the elbow I circled in the middle of the diagram causing that whole zone to not get warm. (Circulator is working fine) This is the supply side of zone 2. Zone 1 heats just fine. I purged each zone about a month ago because last winter I could hear a bit of air in there, but stupidly never checked to make sure each zone was heating properly until now. I assume it's air locked at that elbow since the heat drastically dissipates there?

Also, I want to purge it right now but the Triangle Tube is still at 130 degrees. I hear it's bad to introduce cold water into a hot system so my next question is if I shut off that ball valve, circled in the bottom left, if that's enough to isolate the boiler from the system or not?

Also, is there a chance my air problem is in my primary loop, and not my secondary loops? If so is there a way and is it appropriate to purge just the primary loop and if so how would I go about doing that?

Additional details.
1 story home with basement. 2 upstairs zones are baseboard, downstairs is infloor heat. System pressure about 15 PSI when running.

Thanks in advance for your help!!Name:  heat2.jpg
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Old 09-30-16, 08:12 PM
Join Date: Sep 2015
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That is very strange, are you sure your circulator is working? Maybe the motor is running but the impeller is broken? This would give the illusion its working but no water would actually be moving around. To me it sounds like you have no circulation, not air lock. I would try replacing the circulator and see what happens. Test for power going to the circulator, turn the thermostat on and off and see if you notice a difference in the sound of the circulator motor. I put a screwdriver on the metal body of the motor, and then put my ear on the other end of the screw driver. You will hear the hum of the motor from the screw driver. Have some one turn the thermostat on and off while you listen.

If you are still concerned about air lock at that elbow, install an elbow that has a bleeder valve hole. Put in an automatic air removing float on the elbow (10 bucks on amazon) and u'll never have to worry about air again there.
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