Trouble with one zone and general understanding

Discussion in 'Boiler Forum' started by mln, Oct 14, 2009.

  1. mln

    mln New Member

    Messages:
    15
    Location:
    New Jersey
    I have an old Weil McClain boiler. It's gas fired but I believe that it's a conversion unit on an oil burner. It has four zones. One of the four zones that heats the upper floor is not heating up. It seems like there might be air in the line as it's warm near the boiler but it cools off a few feet away from the boiler. I can't however understand how to get to the bottom of it and would certainly appreciate some input.

    I have attached a photo. The circulator nearest the camera is the problem. The black valve has a hose bib type connection on it. When the thermostat is off, water flows from here. When the thermostat is on it doesn't flow, just light air. I can't seem to locate any other valves on the line upstairs to allow air out.

    A few more notes. The other zones work fine. The pressure gauge reads zero. The valve for the incoming line off the water main was closed. I opened it today (it's still open) thinking that it would add pressure to the system it didn't seem to have any affect. The thermostat seems to work fine, it clicks on the circulator when switched on. While trying things I opened the valve on the overflow/expansion tank and allowed water to drain for maybe 10 seconds, no idea if this was a bad thing to do.

    Does this sound like air, or maybe something wrong with the circulator??
    Any thoughts are very much appreciated.

    Attached Files:

  2. johnjh2o1

    johnjh2o1 Plumbing Contractor for 49 years

    Messages:
    1,142
    Location:
    South*East
    You need to replace your auto feed. If you are getting a zero pressure reading the water is not reaching the 2nd floor. You should be running between 12 & 15 #

    John
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,889
    Location:
    New England
    A boiler running at zero pressure is likely to flash boil in the burner...not good. It's sort of like running your car without the pressure cap on the radiator...it can boil over. It could be that your pressure gauge is bad, though. As noted, it should be in that range. With the type of expansion tank you have, you need to turn off the autofill (if you have one, it is either turned off or not working) or fill valve, then drain all of the water out of the expansion tank, then close that valve and turn the water feed on an pressurize the system to the specified pressure. For it to work right, you need to start with the tank empty and the water off. Then close the valve and turn the water on and pressurize the system.

    If you don't have a bleed valve upstairs, it may be very hard to get all of the air out. it does look like you have fairly big circulator pumps, so they may have enough head pressure so that they can overcome an air blockage IF you have the system filled properly (and at zero pressure, you don't).

    Assuming the flow is up from the pump (might not be, but probably you should be able to tell from an indicator arrow on the pump), if you open that valve below it while it is on, you'd have it sucking air...this is not good for a water cooled bearing!

    See what the pros think...
  4. johnjh2o1

    johnjh2o1 Plumbing Contractor for 49 years

    Messages:
    1,142
    Location:
    South*East
    Do not drain the expansion tank. Get the auto feed replaced first. If the auto feed is not working we don't want to drain any more water out of the boiler. You don't have enough water to reach the second floor. Also by trying to remove the air from the system you are only making matters worse. When you open the air vents you are taking more water out of the system and the auto feed is not replacing it. From what I can see of your system it looks like you can purge the system at the boiler which is a much better way for removing the air. But none of this can be done until the auto feed is replaced. I would advise you to get a pro to replace the auto feed as this requires draining the system. Then after refilling he will remove the air for you. If there is air in system no circulator can move the water. They are not real pumps they just create a small difference pressure between the feed and return. Look at the motor most are 1/8 HP.

    John
  5. mln

    mln New Member

    Messages:
    15
    Location:
    New Jersey
    Thank you for the replies, I have a pro coming out in the morning.
  6. Jon-J

    Jon-J Pipefitter/Plumber

    Messages:
    6
    Location:
    Alaska
    Sounds like an air issue to me. Are there drains on each side of each zone? If so, turn your boiler off and isolate each zone. Take the zone that is giving you trouble and hook a wash machine hose up to one of the drains on the supply zone. Then take a hose and hook it to the return of the same zone. Take the two open ends of the hose and get a small Waynes make up pump and hook the hose thats going to the supply on the zone to the outlet side of the Waynes pump. Get two five gallon buckets and fill with water.
    Prime the pump and then take put a hose on the inlet side of the pump and put it in one of the full buckets. Take the hose from the drain on the return and then put it in the bucket you are sucking out of with the pump.
    It would helpfull to put ball valves on the pump so you can open and close quickly but if not just turn the pump on and let it dead head off the supply drain if you don't have someone helping. Then.....

    1: Turn the drain valve on the supply

    2: Then open the drain valve on the return

    3: Let the pump circ the new water out of the bucket while it is emptying from the other outlet being careful to keep the return hose under the water so you can see if it is pushing air out of the system.

    4: LEt the pump stay running until you have seen that there is no more air being pushed into the bucket.

    5: Shut the RETURN drain first. Do not shut off the pump yet. After return is shut, then shut off Supply. After supply is shut then turn the pump off.

    As long as your zones have these valves on both supply and return i would repeat the process with all the zones.

    With boiler pressure at zero, open each zone one at a time and monitor the gauge press on boiler. You may have up to 30 PSI on each zone depending what stage you were able to get the valves shut off while flushing each zone. Bleed press off system as needed when opening each zone back up.

    This should bleed all the air out of your system. Run the pressure up to 10-18 psi at boiler. The other thing I would do is get rid of those museum piece pumps and get some in line Grunfos pumps. You will probably pay for them in two years just in the power they save you never mind the maintenance peplacing couplers and whatnot. Going to be a whole lot quieter too.
    Sorry so long.
  7. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    Just about everything in the above post is wrong.

    You don't have to run the circulators when purging
    You only need to shut off the valve above each circulator and then put the hose on the boiler drain above that, one at a time.
    Pressure should be 15 lbs all the time
    If you can't develop any pressure than the auto feed valve needs to be replaced.
  8. Jon-J

    Jon-J Pipefitter/Plumber

    Messages:
    6
    Location:
    Alaska
    Um, heh Einstien, I never said anything about running the circulators . I said to ISOLATE each zone from the boiler, TURN THE BOILER OFF and then use a seperate pump to push the air out if they thought there was air in the line.



    If the boiler is installed and maintained properly, the press should not fluctuate more than a few pounds. I am not sure what you have against someone adding something to a forum but am sure I have forgotten more about boilers than you know smarta$$
    Last edited by a moderator: Oct 18, 2009
  9. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    Why would you use a pump when a properly working auto fill will do the job?
    There is no supply fitting on the feeds, just flow check valves, so where's he sposed to attach the hose
    The shutoffs above the circulators, all zones need to be closed or the "pump" will just blow water through the boiler and back out the returns (water takes the path of least resistance)
    And none of that addresses the problem with the defective auto fill which needs to be replaced.

    I have no problem at all with people adding to the forum when they are giving correct advice.

    You have no clue as to my experience or qualifications and believe me at this point you do not want to, nor am I willing to divulge them here.

    And no my name is not Einstein, but thanks for the compliment.
    And I and the other members would appreciate it if you would keep the insults to yourself, thank you.
    Last edited by a moderator: Oct 17, 2009
  10. Jon-J

    Jon-J Pipefitter/Plumber

    Messages:
    6
    Location:
    Alaska
    Your the inspector and your right. My bad. Although every boiler we install is filled with 60/40 glycol/water and not straight water we are by code required to install autofeed/BFP valves I never use them to fill pressure on the sytem because of this. Out of the chance of diluting the glycol of the heating system $$$ and even flooding the house, everyone here recommends leaving that valve off. Different enviroment altogether.

    I assumed that the person was smart enough to make sure the boiler had pressure but that is what i get for assuming. I was explaining the procedure I use here to pressur up a boiler and rid it of all the air in the system. I would leave the valve off though and monitor your system.
  11. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    While we are getting all mushy I have to apolgize for the pump thing because I did not read carefully enough. No damage done anyway, He's calling in a pro.
  12. Jon-J

    Jon-J Pipefitter/Plumber

    Messages:
    6
    Location:
    Alaska
    No worries here. I am off my medication so kid of snapped there ;- )
    We gave them just enough info to to tell the pro who comes over what they think is wrong. Gotta love when that happens.
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