Air in System


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Old 10-22-14, 05:56 AM
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Air in System

Hi.
I have a 40+ year old boiler system that has 4 zones and two circ. pumps.
I recently reconfigured the piping on the further most upstairs level of my house which added 6 liner feet to the zone.
Because my system is tied into an outdoor wood boiler, I have HVAC anti-freeze in the system. So after I completed my pipe work on the upstairs zone I pumped in approximately 3 new gallons of antifreeze (plus what I recovered of the old stuff) into the zone by use of a boiler drain in the basement that is attached to the upstairs zone.
I recently fired up my boiler and attempted to verify no leaks of coolant in the upstairs zone but can't seem to get the coolant to go all the way around and back. Unfortunately I did not install any air bleeds on the upstairs zone because I assumed I could use the boiler drain in the basement to purge the line. So I'm not sure what's happening at this point. I think I may have some other components that are bad needed to ask for some advice.
Starting with the air bleeds I have in the basement. Are they supposed to leak coolant? I currently have caps on the shrader valves but everytime I remove them I get some air followed by a flow of antifreeze.
Also, my expansion tank air pressure level hasn't been checked in several years so I'm sure that needs attention.
Any initial thoughts?
 
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Old 10-22-14, 07:45 AM
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air bleeds I have in the basement. Are they supposed to leak coolant?
No they aren't.

What is the pressure temperature gauge on the boiler reading?
 
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Old 10-22-14, 08:25 AM
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It depends. If I pump the coolant into the system I can be as much as 20psi. If I open the boiler drain up to try and bleed it out then I go down to 7psi or lower. This makes me believe I have other issues with the backflow preventer etc?
 
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Old 10-22-14, 09:04 AM
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Maybe not the backflow preventer, but possibly the 'pressure reducing valve'.

If the boiler is as old as you say, it's also possible that the gauge is inaccurate. You might want to verify that gauge.
 
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Old 10-22-14, 12:08 PM
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Does the pressure reducing valve control the when fresh water gets added to the system?
Also can you recommend a replacement brand?
 
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Old 10-22-14, 01:06 PM
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Does the pressure reducing valve control the when fresh water gets added to the system?
Also can you recommend a replacement brand?
Yes, it's function is to reduce the pressure of the domestic water supply down from 50-60 PSI to the 12 PSI that is typically used in our boiler systems. Think of it as a pressure regulator.

They're all more or less the same, but I would choose one with BRONZE body, such as the B&G FB-38.
 
 

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