How long to purge air ?


  #1  
Old 12-11-05, 02:27 PM
Joe D
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How long to purge air ?

Hello, just finished installing my new/replacement boiler.
Piped it just like described in *Pumping Away*.
So, about how long does it take to purge the air from a run, say about 75' of 3/4 pipe and baseboard , for a zone that takes in one room on 1st and one room on 2nd.?
Doing the purge as described in the Holohan book.
Seems like about 20 min is not enough, still air.
Can you tell when the air has departed the scene by sound ? Or just viewing the discharge into a bucket ?
And,,, why do you suppose the new Taco auto vent onna the top of the scoop is puking more water than air ? Cleaned a few time by pushing down the needle in the valve, did not help.
Pressure is good , 15 # cold, about 22 hot.

Thanks, great info site.
 
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Old 12-11-05, 02:56 PM
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Purging air

I'm afraid I have some bad news. If you have the same zone supplying one room upstairs & one room downstairs with no way to valve each one off, you are going to have a real tough time getting the air out. The air wants to rise & the water will take the path of least resistance (downstairs). You may as well drain the system down & install valves. You are probably going to need them for balancing anyway.
 
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Old 12-12-05, 04:56 AM
Joe D
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Grady, The loop between the two floors is a series loop , no diverter tees, just one continuous pipe/fin tube run.
Do you think I still should install valves ?
When you purge with feed water, is it recommended to lift the arm on the pressure reducer to max press ?

Thanks
 
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Old 12-12-05, 04:01 PM
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2 floors

Lifting the fast fill lever should help. If it is single series loop you should not need the valves but installing manual bleeders in the upstairs would be a major help.
 
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Old 12-12-05, 08:22 PM
J
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Joe I will tell you how I purge the air from my system that has no air bleed valves what so ever. I was never told how to get the air out of my system. After having problems getting the air out I devised my own method, It might not be the right way, but it works.
I have a shut off valve on the return side of the boiler between the pump and boiler, I close that valve. I have a boiler feed valve that puts water into the return side of the zones, which is between the pump and the zones. I turn the electrical power off to the boiler. The reason for that is when I open my zone valves manually they will electrically destroy themselves if they have electrical power going to them. I attach a garden hose to the boiler drain valve and run the end outside onto the yard. I will open one zone valve manually. The boiler has 10 pounds of pressure on it cold. I will then open the boiler feed valve a little, and at the same time I will open the boiler drain valve. I will maintain my 10 pounds of pressure. I will open the two valves simultaneously so I maintain my 10 pounds of pressure on the system. I do not have the valve going full blast, just enough to let a fair amount of water through the system. When both ends of the zone are equally cold I let it run a little longer and call the zone purged. I then open the next zone manually and close the last. When I have purged all the zones I will close the supply and drain valve simultaneously so I do not lose my system pressure. I then close the last zone valve. If my zone valves are left in the open position when the power is turned on they will burn up. Open all valves that should be open and turn on power and I am good to go. I know what I meant to say, I hope you understood it. Hope this works for you.
 
 

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