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purging hotwater boiler

PaulPaul Member Posts: 246
when you are pumping away and prv goes into tee at extrol, the cold water is feeding up supply and hard to tell when you are air free with cold water feed. are you better off putting street  pressureinto bottom boiler drain and forcing hotwater thru system. i have trouble purging with cold water going into header. ice had a post about getting initial air out of new boiler. any ideas or procedures would be great.will you have trouble purging out the air . i seem to have trouble with this arangement. put hose on and let run for long times and air just keeps coming with no end.  thx


  • icesailoricesailor Member Posts: 7,265
    Improperly taught:

    I'm told that I was improperly taught by my old late boss who must have been improperly taught by his old late boss. To always feed hot water boilers at the bottom. Something to do with the cold water and the amount of BTU's to heat it. I didn't understand it at the time. I just did what I was told.

    So it seems that it doesn't matter where you feed it. But, I was also erroneously taught to put a ball valve on the return end of the boiler with a boiler drain above it. That way, any water that comes out the return boiler drain, has to completely go through the system. When the cold water feed goes into the bottom of the boiler, the water is hot when it goes into the system if the burner is running. SO, if you purge the zone, after the air comes, you wait until the hot water comes. Then, shut off the fast fill, boiler drain and open the return ball valve. If the water is circulating, the return should immediately get hot. If it doesn't start rising in a few minutes, purge some more.

    When you purge after the boiler, you only get cold water. I'll still keep doing it wrong because it is easier to purge.

    Does that answer your question?
  • billtwocasebilltwocase Member Posts: 2,385

    You have a big bubble, or possibly a split loop. I prefer to purge as if it had antifreeze, and use a pump to work the air out. The more fresh water you add, the more air you will eventually end up with in the system. Also saves the back from the bucket brigade
  • PaulPaul Member Posts: 246

    yes ice itr makes sense thanks. bill i have heard of the pump method, but never used it. can you explain the procedure and what you need. thx to both of you. good info
  • billtwocasebilltwocase Member Posts: 2,385

    You need a transfer pump, I prefer Wayne, 3 old washing machine hoses, and a 5 gallon bucket. Transfer the water, or antifreeze from the purger, thru the pump, and back into the boiler. Watch the pressure, it will hit 30 with no problem. The boiler drain hose is the discharge side of the pump, acting as the boiler feed, the other hose is suction from the bucket, the 3rd hose is purging into the same bucket. Don't let the suction hose pick up the air, keep them apart. You will need to regulate the pressure by opening or closing the boiler drain. Let it pump around for a while. You will hear it quiet down. I would also check for any splits in the loop. a kick heater, or any other convector that may be set up as monoflow. That needs to be bled manually.  Good luck
  • Ron Jr.Ron Jr. Member Posts: 532
    We feed the boiler both ways

    Like Ice said , theres more than one good place to pipe the boiler feed into .

    Lately we've been feeding the boilers up high in the airscoop with cold water . Before that we'd tee it into the return . Easier to know when you're done if the return pipe gets hot when purging . The only drawback is you have to wait for the boiler to heat back up . Usually after each zone purge . 4 zones takes a while !

     Connecting a washing machine hose from a nearby water heater to the bottom of the boiler works too . Just make sure the boiler relief is piped into a bucket !
  • billtwocasebilltwocase Member Posts: 2,385
    filling boiler

    How goes the battle Ron? This is only after the boiler is filled, and there is an air issue that I will purge that way. I rather feed slowly with the feed valve at first
  • Ron Jr.Ron Jr. Member Posts: 532
    Going good Bill !

    How are things with you ? 
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