2 zone system-no heat upstairs-Boiler doesn't fire when that zone asks for heat

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by MrBostn, Dec 7, 2010.

  1. MrBostn

    MrBostn New Member

    Messages:
    8
    Location:
    Boston. MA
    Hi,

    Glad I found this forum. Perhaps someone can assist me.

    2 zone system. Gas fired-forced hot water (not baseboards but air handlers-one in basement and one of 2nd floor)

    3 circ pumps-and a taco controller. zone 1 works, the hot water system works-all 3 circ pumps turn on.

    Zone 1-everthing works fine
    Hot water heater works fine
    Zone 2-turn on heat, set hallway thermostat on 90F, pump circ starts, air handler upstairs starts and blows (cold) but the boiler never starts up.

    I thought it may be air in the system so turned th the valves in the 2nd floor airhandler to release any air, but no air came out-

    The zone 2 thermostat when turned to heat kicks on the blower in the 2nd floor-can anyone tell me how does the air handler tell the boiler to start? Could that be my issue?

    Zone 1 kicks in the Burnham boiler
    Zone 2 does NOT start the boiler.

    I swapped zone 1 with zone 2 relays in the taco but that didnt work?

    Last year I had what I thought was the same issue-no heat upstairs-I called a random plumber. He and his partner came-(I didn't watch) said the released the air from the system. Heat worked when they left. This year, same issue-I found the valves-turned them-uneventful. No air hissing.

    Any ideas?
    Thank you
    Scott
    Last edited: Dec 7, 2010
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,268
    Location:
    New England
    Depending on how the pipes are run, the bleed valves may not be in the right place to remove any trapped air...trapped air, and the water has trouble flowing. The higher up, the worse it is - the pumps used generally can't overcome the head pressure unless all the air is out. The boiler may be set up to only come on when there is both a call for heat, AND the operating temperature drops below the low point. So, if there is no actual water flowing in that loop, it may or may not be cold enough for the boiler to turn on. Zone one is working, so the return water is colder, and triggers the boiler. There are numerous ways it could be setup, and this is only one of them. I still think it is probably air.
  3. MrBostn

    MrBostn New Member

    Messages:
    8
    Location:
    Boston. MA
    Hi Thanks for replying.

    It probably is air as this is the same thing that happend last year.
    Also when I unscrew the valves in the 2nd floor air handler, nothing comes out. no water, no air.

    When I go to the basement airhandler and loosen the valves, water spurts out as expected.

    So my quetion is, how do I get air out of the 2nd system??

    Thank you
    Scott
  4. johnjh2o1

    johnjh2o1 Plumbing Contractor for 49 years

    Messages:
    1,143
    Location:
    South*East
    You don't have enough pressure in the boiler to reach the 2nd floor. The gauge should read 15 to 18 lbs.

    John
  5. rmelo99

    rmelo99 Network Engineer

    Messages:
    349
    Location:
    Connecticut
    So I'll provide some advice based on what you told us, so maybe you can troubleshoot and verify some more stuff.

    You mentioned that there is a taco controller that the circs are connected to. They usually have lights that correspond to each zone. Is that what you are using to say that the circ are running? The reason I say this is that is that the light on means that the thermostat/or airhandler is properly communicating the call for heat to the taco controller for that zone. The taco controller then activates a relay (little cube thing) that runs the circ. Your circ could be bad/not running. I would do the screwdriver to the ear and to the circ for that zone to confirm it is in fact "running" or at least being energized.


    If you have air and have been running the circ dry it could be shot... they are generally water cooled/lubricated. John was right that you will need generally need upwards of 15lbs of pressure for a 2 story house.

    To purge air really depends on how you are piped. If you can provide pics we can prob guide you on which valves to close or open to purge the air. Piping to an hydrocoil is generally much easier to purge air than say a loop that feeds a bunch of radiators.

    On my multi zone setup I usually close the valves to the other zones both supply and return side since I can. Then I have a close the ball valve on the return side of the zone i need to purge because I have a boiler drain(hose spigot) valve right above that one. I connect a short washing machine hose from that to a bucket. That allows me to run water up the supply side for that zone only and push water and air out of the boiler drain on the return side. I move the valve on my auto-fill to quick and close the drain valve as soon as I get a steady non-spurting stream of water.

    After the drain valve is closed. I reopen all the valves to that I closed before purging.
  6. MrBostn

    MrBostn New Member

    Messages:
    8
    Location:
    Boston. MA
    IMG00010-20101207-1113.jpg IMG00009-20101207-1113.jpg IMG00008-20101207-1113.jpg

    I did the screwdriver to the ear thing and it does sound like it's spinning.

    Here's a few pics

    I'll take one of my airhandler upstairs and my piping by the boiler.

    Not sure if I mentioned this but I swapped what seem to be relays in the taco, but that did nothing.

    Thank you all.!
  7. MrBostn

    MrBostn New Member

    Messages:
    8
    Location:
    Boston. MA
    More pics coming soon. Inside the boiler there's a psi gauge. It shows a tad above 20psi
  8. rmelo99

    rmelo99 Network Engineer

    Messages:
    349
    Location:
    Connecticut
    So your supply side piping with the circs is similar to mine and you do have valves that you can use to close off the other zone you are not purging. Try and get some equivalent pics of the return piping and valves for the zones.
  9. MrBostn

    MrBostn New Member

    Messages:
    8
    Location:
    Boston. MA
    pic of 2nd floor air handler

    Here's a few more, I hope they're helpful.

    the 2nd floor (You may notice the TACO says 3rd floor heat-that's what I call the 2nd floor)

    Anyway, the 2nd floor air handler is horizontal, above my wifes closet. this pic shows the unit.

    the valves: two are on the bottom, two on top. When loosened, the top don't have air, or water that comes out. This pic shows the two on top. Sorry for the sideways pic. Taken with a blackberry

    The two on the bottom, one spits, one, occaisionally spits some water, but only after running the system a bit..

    IMG00018-20101207-2042.jpg
  10. MrBostn

    MrBostn New Member

    Messages:
    8
    Location:
    Boston. MA
    I just took some pics with my camera, now they are too large for the site...ugh. I'll get more organized tomorrow and follow up.

    I appreciate everyones input and help.

    Scott
  11. MrBostn

    MrBostn New Member

    Messages:
    8
    Location:
    Boston. MA
    To answer you..yes I have three corresponding valves I can turn off.
  12. rmelo99

    rmelo99 Network Engineer

    Messages:
    349
    Location:
    Connecticut
    Here is what I would do. I would close the valves on the other 2 zones. The yellow valves above and below the circs. I would make sure to either turn down the stats or pull the relays for those 2 zones. you don't want the pumps running if you have the water cut off to them. Those green things north of the pumps are check valves that make sure water only flows one way....up.

    Ideally you would want to pump water up into that zone and purge air out at the end of the loop back down at the boiler. It sounds like you have some valves up @ the air handler where you can push water to and get air out from the loop there. Your pump isn't going to do this....it has to be water pressure. So you will have to coordinate with someone to turn your autofill (fresh water ) up to rapid. Usualy it looks like a bell with a lever over it that can be lifted. This will start filling your boiler. Since the other zone will be closed off, the water will only have one place to go up that zone. Now with the valve open up @ the air handler you should hear the water comin....first instinct could be to close the valve once you get water...DONT.

    You want to push water until it runs with no air bursts or until it is steady. Then you can quickly close the valve and put the auto fill back to normal position. Check your boiler pressure...make sure it is still 15-20psi or what it was before. Then go open the valves down @ the boiler so all zone are open.

    Check the return for that zone, if the water made it's back down to the boiler it will usually warm up the return side of the pipe.
  13. MrBostn

    MrBostn New Member

    Messages:
    8
    Location:
    Boston. MA
    Solved!


    Seems my issue was combination pressure/water/air.

    Last night, when I was turning the coin valves on the air handler on the 2nd floor, I didn't get air or water...nothing came out. I knew my circ pump was working. My PSI was about 20.

    So what I did today was add water to the system. Not too much I released the valve (forget what you call it) letting water flow for about 5 seconds. The PSI didnt move. After I added the water, I turned all the heat on in both zones. Zone 1 was working, as it always has, I went to zone 2, went to the valves and finally got air to relase, after a few seconds water spurted out.

    Not long after that, heat began to flow.

    If my post contains typos, I apologize, I'm typing on a Dell mini 9. Tiny keyboard.

    I realize the air issue may arise again due to the water added. But I'm happy for now.

    Thank you to all of you. Your comments helped me understand my system, and save me a service call :)

    Merry Christmas to everyone!

    Scott

    GO PATS!
  14. ushercules

    ushercules New Member

    Messages:
    1
    Location:
    Massachusetts
    Your solution helped me


    Thank you MrBoston. Your solution helped resolve my issue too. Sincerely appreciate it (saved me couple of hundred dollars today)

    regards
    Chris
  15. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,048
    Location:
    Cave Creek, Arizona
    If you do not have water coming out of the air vent the unit will NEVER heat, but that should have nothing to do with the burner not coming on, unless you did not check it immediately and it has shut down on high temerature limit because there is no circulation.
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