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Size expansion tank for 1000 gallon storage?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by cbb, Aug 30, 2012.

  1. cbb

    cbb Member

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    Gentlemen;

    I understand that a rule of thumb for an expansion tank is 10% of the volume.

    I was wondering what some of you are using for expansion tanks. Bladder type? Make and model?

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  2. Blevesque

    Blevesque Member

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  3. JP11

    JP11 Minister of Fire

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  4. cbb

    cbb Member

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    Thanks guys!

    JP; The two exp. tanks... because you have two 500 gal. stacked?

    In my case it will be one 1000 gallon tank
  5. JP11

    JP11 Minister of Fire

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    Volume is volume. I have two 500s vertical. Now.. as my contractor friend says.. You never really KNOW overkill. You ALWAYS find out underkill.

    I've heard of people doing it with less. I just figured it was easier to have plenty than wonder if I had enough. It's what Mark at AHONA recommended.

    JP
  6. taxidermist

    taxidermist Minister of Fire

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    mine is sama as JP!!
  7. heaterman

    heaterman Minister of Fire

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    Per ASME boiler code Table 272B based on water temperature of 195*, fill pressure of 12 psig and maximum operating pressure of 30psig

    System volume in gallons / Tank capacity
    300 / 45
    500 / 75
    1000 / 150
    2000 / 300

    And remember to include the volume in the boiler, tubing and pipe.
  8. DaveBP

    DaveBP Minister of Fire

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    Is that tank volume or acceptance volume?
  9. BoilerMan

    BoilerMan Minister of Fire

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    I believe tank volume. It's 15% total system volume.

    TS
  10. heaterman

    heaterman Minister of Fire

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    Those numbers are for actual tank volume, not acceptance.
  11. jebatty

    jebatty Minister of Fire

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    I have a SX-160V and a SX-40V for 1000 gal storage + estimated 60 gal boiler/system. The system low temp is about 65F during non-use, and 192F maximum during use; pressure about 11 psi minimum and 25 psi maximum.
  12. dogwood

    dogwood Minister of Fire

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    I am concerned by the amount of expansion tank volume being recommended above to include Ahona recommending two SX110s for 1000 gallons and particularly the ASME table recommending 150 gallons for 1000 gallons of storage. Similar to Jim, for 1000+ gallons of storage, I'm installing an Amtrol Extrol SX-160 and an SX-30 . That would add up to 100 gallons of expansion tank size (86 + 14 gallons) with an total acceptance volume of 57.3 gallons (46 + 11.3 gallons). I based this sizing in part on two earlier posts by Joe Brown from Brownian Heating and Jim (jebatty) using acceptance volume as my yardstick.

    Here are quotes form those posts:

    Joe said, "If I'm using the chart correctly, you have an expansion factor of 0.0351 (assumed for a worst-case 40-200 degree reheat).So, if you have 1000 gallons, that means you need a tank that can accept 35.1 gallons. Of course, you want to size this for the whole system, not just the tank, so add the fluid volume of each boiler, and a few percent more for piping. It never huts to over-size an expansion tank, except when you have to write a check for it... (let's call it 40 gallons, for the sake of discussion)"

    Jim said, "After running a quick search, did not find answer in this forum as to how much water expands with temperature, which is important in sizing a non-pressurized tank and in sizing an expansion vessel in a presurized system. After *oogling this, these are helpful:
    http://www.newton.dep.anl.gov/askasci/chem03/chem03335.htm
    http://www.ucdsb.on.ca/tiss/stretton/chem2/data19.htm.
    A statement is made that, “from freezing to boiling, [expansion] is 4.3%.” Looking at the data table, this seems to indicate that expansion in moving water from 50F (10C) to 200F (95C) is 3.8%. So, 1000 gal of storage needs at least 38 gallons of expansion over this temp range. Plus a margin of error—maybe plan for 5% as a rule of thumb?"

    I've more expansion room than these two calculations say is needed, but considerably less than Heaterman's ASME table would indicate is warranted. I can't find any fault with Jim or Joe's calculations or reasoning. Jim's system as mentioned above sounds like it is working just fine. So Heaterman or Jim or any other knowledgeable person, are the ASME calculations overkill? Am I missing something here?

    Mike
  13. I'm about to order parts for my upcoming 1000 gallon storage project. So I have the same questions.

    I've used the amtrol calculator with the following asumptions.

    1000 gallons
    60 min temp
    200 max temp
    12 psi min
    25 psi max


    And it calls for an amtrol ax200v which has a 34 gallon acceptance volume. And a 110 gallon volume.

    http://www.amazon.com/Amtrol-AX-200...e=UTF8&qid=1346949769&sr=1-1&keywords=Ax 200v

    Is there a reason that I couldn't use an sx160v? It has a 46 gallon acceptance and 86 gallon max volume.

    http://www.pexsupply.com/Amtrol-118-155-SX-160V-Extrol-Expansion-Tank-86-Gallon-Volume-7370000-p

    This tank would be an addition to the existing expansion tank serving the boilers already. I don't need an asme rated tank for code. Just want it to work right.
  14. jebatty

    jebatty Minister of Fire

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    Based upon my experience, only a SX-160V will not do it, which is what I had before adding the 40, and I too thought the 160 would be enough. My heated building is single level, and I only needed to work with 14' elevation. I reduced tank pressure to 8 psi to make this work within normal heating operational range, but then when tank temps fell to below about 100F, I would get air in the system due to contracting water. The added SX-40V perfectly solved the problem.
  15. Floydian

    Floydian Feeling the Heat

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  16. BoilerMan

    BoilerMan Minister of Fire

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  17. dogwood

    dogwood Minister of Fire

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    Thanks Noah and Taylor. This link will take you directly to the Caleffi Idrionics issue Taylor mentioned: http://www.caleffi.us/en_US/caleffi/Details/Magazines/pdf/idronics_10_us.pdf. Noah (Floydian), I never could figure out how to use the tables Eliot inluded in the post you provided the link to. I'll try to figure them out again. I'll try to work the formulas in the Caleffi article too, and see if I can come up with comparable results using both approaches.

    Mike
  18. maple1

    maple1 Minister of Fire

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    Anybody have some non-diaphragm experience or input they care to share? I have one ready to hook up to my project - it's a 110 gallon propane tank, for two 330 gallon storage tanks. I'm not 100% this will work the way I would like, but the tank fit my space & it was cheap, so I decided to give it a shot. I guess the main thing I'm thinking about naturally is the air from the expansion tank working its way into the water in the storage tank over time. Once I have everything up & running, and the old boiler & oil tank out of here & the basement cleaned up, I can re-plumb later with diaphragm tanks(s) if this doesn't work out the first winter, and use the 110 gallon tank for that much extra storage. I would have preferred to get the expansion tank up above storage, but no way to do that - so it's on floor level. I may be able to get it up to my joists once I get the old oil tank out - I plan on leaving that there for this winter in case I need to suddenly re-hook something up to it.
  19. BoilerMan

    BoilerMan Minister of Fire

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    I think with a non-diaphram tank you need to have it above the storage. You want to put compressed air in it, so drilla 1/2" hole and put a tire valve stem in it, or rig up some fittings so you can put air in through an opening above the water line.

    TS
  20. I don't think it needs to be. Leave the expansion tank valve closed.
    Fill your system,
    Charge the non bladder tank to 12 psi,
    Open the expansion valve, and the air pressure will keep water out until you heat the water.

    Of course you'll need a sight gauge and a inlet for the water on the bottom of the tank.

    Lol, sounds so easy maybe I should look for a couple of old water heaters to use for expansion!
  21. CMAG

    CMAG Member

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    About 30 years back when I was doing oil service all but a few were expansion tanks, they worked fine just a **** to drain when they got water logged.
    They had no charge just drained them once a year.
  22. mousebndr

    mousebndr Member

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    I dont know if this is different for each vendor of tank, but I used this formula on mine...

    V = n / 1 - ((Pi + 1) / (Pf+1))

    V = expansion volume
    n = internal vol of tank
    Pi = precharge pressure of tank
    Pf = maximum pressure of safety valve

    n is calculated by n = e * C
    e = expansion coefficient
    C = total capacity of the system


    Check out...
    http://www.huntheat.com.au/admin/upload/IMERA Expansion Tanks Brochure.pdf

    Look on page 7
  23. maple1

    maple1 Minister of Fire

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    I've got it all ready to go - air valve, guage, drain on bottom, valve on top for bleeding purposes, sight guage of semi-see thru pex. And fresh paint. It's just waiting on what it's going to be hooked to to get finished.
  24. heaterman

    heaterman Minister of Fire

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    Most of this very good article regarding expansion tanks was adapted from Taco's website. The very first sentence of the paper will give you a rough guideline for sizing but there is a wealth of info about placement of the tank in the piping as well as in relationship to pumps. Fill pressure and how to determine the correct psi is also covered. (Hint, 12 psi is not correct for all applications)

    Tons of good info. I knew I had it bookmarked somewhere.........

    http://www.vemcoinc.com/pdf/Technical Library/Expansion Tank Application.pdf
  25. BoilerMan

    BoilerMan Minister of Fire

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    Good read, I thought an air control (plain steel tank) tank had to be above the boiler.

    TS

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