Ever switched off and drained your hot water system to fix a leak, only to turn on your water and find no hot water?

Method 1
Method 1 of 2:

Primary Method

  1. 1
    Make sure your hot water supply is on.
  2. 2
    If the cold water runs OK, but the hot water doesn't, or runs slowly then trickles off, then you may have an airlock, which is when air in the pipes isn't being moved by the hot water, thereby blocking the pipe.
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  3. 3
    Take a length of garden hose (about 1 foot) and some duct tape.
  4. 4
    Use the duct tape and hose to connect the cold water tap to the hot water tap.
  5. 5
    Open the hot water tap.
  6. 6
    Open the cold water tap for 3-5 seconds.
  7. 7
    Make sure that your airlock is fixed!
  8. 8
    Check the hot water at another tap.
  9. 9
    Repeat steps 5-8 two or three times.
  10. 10
    IF the hot water is working, switch off all taps and remove your hose.
  11. 11
    If not, call a plumber!!
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Method 2
Method 2 of 2:

Alternative Method

  1. 1
    Disconnect the blue pipe from the back of the washing machine.
  2. 2
    Disconnect the red pipe that leads from the washing machine to the hot water pipe (i.e. the end that is not connected to the hot water connection of the washing machine
  3. 3
    Connect the end of the blue pipe that was connected to the washing machine to where you just removed the red pipe
  4. 4
    This now creates a 'U' between the cold and hot water pipes.
  5. 5
    Open the hot water tap.
  6. 6
    Open the cold water tap for 3-5 seconds.
  7. 7
    Make sure that your airlock is fixed!
  8. 8
    Check the hot water at another tap.
  9. 9
    Repeat steps 5-8 two or three times.
  10. 10
    IF the hot water is working, switch off all taps and remove your hose.
  11. 11
    If not, call a plumber!!
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Community Q&A

  • Question
    How do I fix an airlock in a hydronic heater that is connected to a hydronic water system in a condo community?
    Community Answer
    Community Answer
    Within your distribution piping, normally at the heater a small tank is mounted on top of the piping, or there may be a small spring-loaded valve. The tank fills with water and presses against a rubber bladder pressurized with air, which fills and empties in response to system pressure. The bladder breaks or leaks and no longer maintains system pressure and needs to be replaced. The spring-loaded valve works in opening and releasing high pressure and air during extreme system pressure. This valve can be manually released (warning: hot temperatures!) to bleed off pressure/air. This valve fails when the spring breaks or gets soft and must be replaced.
  • Question
    How do I remove an airlock in my hot water system?
    Community Answer
    Community Answer
    You remove the airlock from your hot water system by flooding it, and then it becomes a waterlock system.
  • Question
    What do I do if the hot water doesn't work consistently?
    Community Answer
    Community Answer
    Call a plumber. If that doesn't work, mix boled water with water from the cold tap to take a bath.
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Warnings

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Things You'll Need

  • Piece of hose
  • Duct tape
  • Qualified plumber!!

About This Article

wikiHow is a “wiki,” similar to Wikipedia, which means that many of our articles are co-written by multiple authors. To create this article, 13 people, some anonymous, worked to edit and improve it over time. This article has been viewed 343,031 times.
183 votes - 62%
Co-authors: 13
Updated: February 24, 2021
Views: 343,031
Categories: Water Heating Systems
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