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How do I bleed hot water baseboard system when zone valves, drain valves, and pump all on one side?

pqsmithpqsmith Member Posts: 3
How do I bleed hot water baseboard system when zone valves, drain valves, and pump are all on one side, and the shut off valves are on the other? From my research, mine is not a typical set-up. First, is it ok that the system is set-up this way? Does it function fully and optimally? Second, can the zones be bled properly? If so, how? Pictures Attached. One side of boiler has circulator pump, zone valves, and drain valves. Other side (return) has shut-off valves and cold water fill?


  • JUGHNEJUGHNE Member Posts: 4,141
    How do you know it needs bleeding?
    Do you have 3 zone valves, it look like you have 3 circuits leaving the top of the boiler which is most likely the supply (water out).
    Have you looked on the ends of the BB heaters for a small air vent.

    If it is almost working and you hear waterfall gurgling in a BB maybe just that one has air trapped. A little air in a BB will stop the flow.
    Doing a major bleed on the entire system may get more involved than you need.
  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 3,662
    Shut the boiler off at the service switch.Turn all your thermostats down which will close all the zone valves. Hook a hose to the boiler drain above the zone valve on the zone you want to bleed.

    Open the boiler drain you just connected to bleed that zone.

    The closed zone valve will keep water from backing out of the boiler and will force water through the zone to your hose.

    Reverse all the above and put the boiler back into operation
  • pqsmithpqsmith Member Posts: 3
    Thank you E! That was really direct and to the point. A quick follow-up questions: Do I need to close the other two zone shut-off valves (yellows) while bleeding the other one. And does it matter which I bleed first: top floor, bottom floor? Thanks again for your concise response.
  • JUGHNEJUGHNE Member Posts: 4,141
    Do you have 3 electric zone valves, I only see two.
  • hot rodhot rod Member Posts: 7,785
    And put the fill valve in the fast fill position when you purge or you could add air instead of removing it.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • JUGHNEJUGHNE Member Posts: 4,141
    Yes, swing that bail handle lever to fast fill and you will hear more water flowing.
    The reason I asked if you have a major or minor problem is that the more fresh water you introduce the more air comes with it.
    Do you have some form of air eliminator on the piping? This automatically eventually removes most air. It may be near the expansion tank. Neither of these are shown in your pictures.

    If you go for the power bleed, you could still have some air trapped in BB heater later. What I do is run the water up to temp then shut off the pump. Wait maybe 30 minutes and the minor amount of air will find its way up to BB and then the small manual air bleed vents will remove it. It may take more than one attempt. IMO
  • HVACNUTHVACNUT Member Posts: 1,025
    edited September 2017
    Replace the auto vent first.
    It's on top of the 1/2" vertical pipe near the supply.
    You lucked out by having a ball valve there so you don't have to take pressure off the boiler.
    Close the ball valve, remove old vent.
    Install new with tephlon tape on the 1/8" threads.
    Hand tight only.
    It will take a few days after your regularly using the heat on all zones before all air is vented, but it's better than purging and adding gallons of oxygenated water to the system.
    A zone should only be purged if it's air bound and not heating.
  • pqsmithpqsmith Member Posts: 3
    Thank you all so much for your comments and expertise. I really appreciate it.
  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 3,662
    Yes, I would close all the zone valves and bleed them 1 at a time (if they all need bleeding)
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