# Expansion of water

Posted By jebatty, Jan 15, 2008 at 3:55 PM

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1. #1

### jebatty Minister of Fire 2. ```NULL ```

Jan 1, 2008
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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 made is "from freezing to boiling, [expansion] is 4.3%." Looking at the data table, 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?

2. #2

### Eric Johnson Mod Emeritus 2. ```NULL ```

Nov 18, 2005
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Joe Brown did some rough calculations and I think his conclusion was that with 1,000 gallons of pressurized storage you could get away with a 40-gallon (hw) tank, but that 80 would be the safe bet. It's around here somewhere--probably worth digging up, as he walked us through the calculations.

EDIT: Here it is; second page:

https://www.hearth.com/econtent/index.php/forums/viewthread/11559/P15/

3. #3

### wdc1160 New Member 2. ```NULL ```

Dec 28, 2007
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Lafayette IN -BoilerMakerCountry
Dude don't even mess with googling it,
You'll start getting confused with acceptances, max acceptance, volume, and what the manufactuter wants.
Find the Tank(brand, mfctr,model) you want, then adjust the pick based on what like about the tanks and what manufacturer says its capable of.

Use this as an example

http://www.mmcontrol.com/documents/pdfs/Cashacme/tv.pdf

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