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Thread: Radiant heat zone not letting water flow

  1. #1
    DIY Junior Member Michigan_Tony's Avatar
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    Default Radiant heat zone not letting water flow

    I live in Michigan, it's cold here, cold enough that my water line to my outdoor spicket froze and burst.

    My house has 4 zones.
    I have a Slant Fin Galaxy boiler
    I've had my walkout basement zone freeze (so I thought) in the past
    The basement zone valve motor went bad
    Upon receiving parts, I installed the new motor and a kit to adapt the new motor allowing the motor to be replaced without breaking the water seal. So when replacing this I had to open the system.
    Prior to replacing and after replacing the part, I've not been able to get water to flow through the basement zone (by normal means, using the manual switch, or using the house water feed).
    I've tried closing all returns from all zones and opening the system at the return of the basement zone but the house supply won't push water through. It does through all the other zones. I know the valve lets water out because I can back flow through the valve if I open the return of the basement zone. I've applied gentle heat everywhere along the exterior walls with small space heaters. It's been roughly 25-29 out the last two days. I had the basement up to 75 the last two days.

    Do you think the zone is frozen?
    If it is frozen, do you have any recommendations for thawing?
    If it is frozen, and I can't thaw it, should I close that zone and leave the drain valve in that zone open to relieve pressure until it warms up outside and can thaw?
    Is there anything else that could prevent water from flowing through the zone?

    This zone flows from the boiler like this:
    __ ____ ____ ____ ____ ____
    |_____| |_____| |_____| |_____| |_____|
    1 2 3 4 5
    1. baseboard on interior wall
    2. baseboard on exterior walkout wall
    3. baseboard on exterior walkout wall
    4. baseboard on interior wall
    5. baseboard on exterior non walkout wall

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    Air can stop flow in any low pressure heating loop. The pumps are often small enough where they cannot push water through an air lock. Normally, that air migrates to the highest point in the system, and wouldn't be an issue in the lowest zone, but no guarantees. If you have a separate valve on the that loop, open up the supply and flush it to see if water flows - this may get rid of the air, if that's it, and if no water flows with that higher pressure, that implies a blockage.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    DIY Junior Member Michigan_Tony's Avatar
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    Thanks for the reply.

    The water supply will not flush the zone. It flushes the other zones but not the basement zone.

  4. #4
    In the Trades Tom Sawyer's Avatar
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    Quote Originally Posted by Michigan_Tony View Post
    Thanks for the reply.

    The water supply will not flush the zone. It flushes the other zones but not the basement zone.
    Yep, it's frozen.
    [B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]

  5. #5
    DIY Junior Member Michigan_Tony's Avatar
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    The next week is going to be colder than it has been the last two days. I haven't been able to get it to thaw yet. I keep moving heat along the zones by the walkout wall. I've been able to get water to drip out due to the heat applied-about a gallon but I can't pinpoint what is frozen.

    Assuming I can't get it thawed, and with it being colder, should I close off the zone from the system and leave the drain to the zone open?

    Any other suggestions?

  6. #6
    In the trades Dana's Avatar
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    Unless you're actively working on thawing it out, close off the zone for now, but don't leave the drain open.

    You may be able to bring the room sufficiently up to temp with a couple of 1500W electric space heaters to thaw the zone plumbing.

    The most likely frozen points are probably along the walk-out wall, or any un-insulated section of above-grade wall. A hair drier blowing directly down the fin tube can put quite a bit of localized heat into the system and thaw it out, if you can figure out exactly where your ice-plug it. Popping off the end cap of a baseboard and directing the flow of the hair drier inside the housing of the suspect section for several minutes may do the trick.

  7. #7
    DIY Junior Member Michigan_Tony's Avatar
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    I'm starting to think it's not frozen. I've applied heat all along the circuit. Today I used a 30,000 btu salamander type heater and heated the walls closest to the open valve and worked my way backwards. I had the basement up to 90. Some water would drip out occasionally.

    I'm thinking there is an air block but I know nothing about how to get the air block out. If it's an air block, would the main supply be able to overcome it and push through? Is it possible that the water feed would not have enough pressure to push through? I've also tried putting a wet dry vacuum on the drain valve while trying to push water through using the feeder.

    Any other suggestions?

    Thanks for your replies.

  8. #8
    In the Trades Tom Sawyer's Avatar
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    Some water would drip out occasionally...= frozen
    [B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]

  9. #9
    DIY Junior Member Michigan_Tony's Avatar
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    I'm all set. I too thought it was frozen but now I'm begining to wonder if heating the pipes just warmed the water and created enough expansion to push some water out...

    I had an air lock which I was able to overcome by increasing the system pressure from 18 to 23PSI. Thanks for the help. I'm all set now.

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