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Help with Expansion Tank Alternatives

JHMartin Member Posts: 40
Thanks to all the help from you here on the board, I have made good progress with Boiler #1 and was able to purge out all sorts of black water, sediment, and entrapped air. Now I'm on to Boiler #2 and have a problem with the expansion tank's location. I want to replace the ball valve just above it with one meant for water (and the 1/2 x 1/2 x 1/2 tee with a 1/2 x 1/2 x 3/4) but the tank is already so close to the ground I can't even get my pressure gauge on to the Shrader valve as it is. The tank is also sandwiched right up against a gas pipe (it's the tank in the lower right in both pics). I thought I was pretty good at visualizing things until I started redoing plumbing in three dimensions. I would appreciate your suggestions.


  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,002
    edited April 2
    I would move the tank to a serviceable location.

    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
    Larry WeingartenkcoppJHMartin
  • mattmia2
    mattmia2 Member Posts: 9,646
    Ell and a couple nipples and turn it on its side. Maybe a 45 in there too. Make sure the piping it is hanging from is supported.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,837
    edited April 3
    There are several ways to move the tank. This might me the easiest.

    Turn the Tee fitting to the bottom of the Air Separator so the branch feeds it.
    Connect the water from the auto-feed reducing valve from the left run ( that can be 3/4").
    Connect a nipple to the other side of the run (1/2") and then an elbow to another location where it is easy to service. This will gain you several inches from the end of the expansion tank feed to the new expansion tank. Just be sure to support the long 1/2" pipe that will hold the expansion tank. as previously mentioned by @mattmia2

    The final location of the expansion tank can be above or below the air separator. They even make floor mounted models like the SX-30V
    A little overkill but it will do the job without the need to support the connecting pipe.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    JHMartinAlan (California Radiant) ForbesPRR
  • hot_rod
    hot_rod Member Posts: 22,143
    I don't like the tank directly under the separator. They tend to collect dirt and debris along with air removal. the dirt can clog the expansion tank connection, or drop debris down onto the diaphram.

    Arm off to the side can help, like Eds "new location" pic.

    Here is an example of that exact sep that has plugged.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Alan (California Radiant) Forbes