# Size expansion tank for 1000 gallon storage?



## cbb (Aug 30, 2012)

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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## Blevesque (Aug 30, 2012)

Here is the amtrol calculator http://www.amtrol.com/support/extrol_com_sizing.html


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## JP11 (Aug 30, 2012)

E


Blevesque said:


> Here is the amtrol calculator http://www.amtrol.com/support/extrol_com_sizing.html


Picture is worth a thousand words.. I was going out to take a pic of my tanks.  Two SX110Vs


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## cbb (Aug 30, 2012)

Thanks guys!

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

 In my case it will be one 1000 gallon tank


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## JP11 (Aug 30, 2012)

cbb said:


> Thanks guys!
> 
> JP; The two exp. tanks... because you have two 500 gal. stacked?
> 
> In my case it will be one 1000 gallon tank


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


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## taxidermist (Sep 2, 2012)

mine is sama as JP!!


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## heaterman (Sep 4, 2012)

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.


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## DaveBP (Sep 5, 2012)

Is that tank volume or acceptance volume?


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## BoilerMan (Sep 5, 2012)

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

TS


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## heaterman (Sep 5, 2012)

Those numbers are for actual tank volume, not acceptance.


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## jebatty (Sep 6, 2012)

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.


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## dogwood (Sep 6, 2012)

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


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## mikefrommaine (Sep 6, 2012)

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.


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## jebatty (Sep 6, 2012)

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


 
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.


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## Floydian (Sep 6, 2012)

Some good info here:

https://www.hearth.com/talk/threads/expansion-tank-volume.51241/


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## BoilerMan (Sep 7, 2012)

Caleffi idronics addresses this in the biomass issue.  Page 47  for ex-tank calculations. 

http://www.caleffi.us/caleffi/en_US/Site/Technical_library/Idraulica_magazine/index.sdo

TS


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## dogwood (Sep 7, 2012)

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


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## maple1 (Sep 7, 2012)

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.


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## BoilerMan (Sep 7, 2012)

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


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## mikefrommaine (Sep 7, 2012)

Taylor Sutherland said:


> 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


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!


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## CMAG (Sep 8, 2012)

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.


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## mousebndr (Sep 8, 2012)

cbb said:


> 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?


 
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


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## maple1 (Sep 8, 2012)

mikefrommaine said:


> 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.
> ...


 

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.


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## heaterman (Sep 8, 2012)

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


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## BoilerMan (Sep 8, 2012)

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

TS


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## maple1 (Sep 8, 2012)

heaterman said:


> 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


 
Thanks for that. Doesn't leave me too hopeful that my planned setup is going to work too good. Maybe I better start shopping some bladder tanks in case I have to make some quick changes.


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## dogwood (Sep 8, 2012)

Excellent article Heaterman. Thanks. It says in its chart for 1050 gallons (for up to a two story house) you'd need only 36.9 gallons of acceptance and 91.45 of volume. I've got 57.3 and 100 gallons respectively and am feeling reassured. Similar numbers to what Joe Brown and Jebatty had come up with too.

Mike


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## dogwood (Sep 9, 2012)

Heaterman, I reposted the link you provided above to the article on sizing expansion tanks into the Links to Articles and Resources on Central Heat sticky. Hope you don't mind.

Mike


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## rkusek (Sep 10, 2012)

Taylor Sutherland said:


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


 
Are we in agreement that Maple1's tank with the pex sight tube and schrader valve on top is OK?  I'm currently taping the holes in an old 250 gal propane tank that I plan to mount vertical.  My system volume will roughly be around 1250 gals (two 500g storage tanks, 750' 1.5" UG, boiler, and this homemade expansion tank).  The elevation change works against me too since the home sits on about 15' higher ground than the pole barn where boiler and storage sits.  My cheap gauges seem to indicate about an 8 PSI difference right now so Heaterman's guide seems on target.  When they say tanks have to be mounted above the boiler are we talking when you cannot add air to the tank and monitor the water level?


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## BoilerMan (Sep 12, 2012)

I believe the idea is to have the line to the tank be at the point that the air elimination velve would be, like the air scoop.  The air that would normally be vented or burped during fill up would be directed to the tank.  Someone correct me if I'm wrong, but having the tank above the boiler is ideal making the best use of the tank's volume.  Also I'd investigate the "tank fitting" that they have in the article.  I think it's a one way valve not allowing air to be drawn into the system if there is a leak. 

TS


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## Armaton (Sep 15, 2012)

Has anyone used the Cash-Acme TV series expansion tanks? They have a TV-160 that is a 96 gallon Tank with 64 gallons acceptance? Price is less than an Extrol SX-160V also? What do you think,would this single tank be enough for a 1000 gallon system? Just a thought.


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## mikefrommaine (Sep 16, 2012)

I don't have any experience with those tanks, what is the pricing?


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## mikefrommaine (Sep 16, 2012)

Here is a screenshot of the watts calculator. 1025 gallons, 12-30 psi, 55-195 temp range. Requires 94 total and 34 acceptance. So from what I know, this would be enough expansion for the tanks themselves but not the boiler and distribution system.

Anyone see a problem with me using this tank (cash acme tv-160) for ONLY two 500 gallon propane tanks? I already have an amtrol #30 for my oil boiler and an amtrol #60 for my wood boiler.


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## maple1 (Sep 16, 2012)

Bit of an aside, but I am aiming for high pressure of quite a bit lower than 30psi - my current system never goes above 20 and I'd like to keep things that way if possible.

Man these diaphragm tanks are expensive - I plugged my numbers into the Amtrol sizer, and it spit out a tank that's in the $3500 range (AX-180v). WTH? That's a 34/90 tank - why the heck does it cost so much? My supplier deals in B&G tanks - they have a HFT-160V that is a 86 gallon tank. It's $570 on Pexsupply - I'll have to see how much it is to buy it here. The supplier guy's eyes went all buggy when I told him I've got 750 gallons in my system - I'm in uncharted waters around here.


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## mikefrommaine (Sep 16, 2012)

Try the watts calculator. It gives the required total and acceptance volumes instead of tank recommendations.

http://www.watts.com/pages/support/sizing_ET.asp

I think the amtrol ax tanks are asme rated. Which are $$$$$


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## JP11 (Sep 16, 2012)

mikefrommaine said:


> Try the watts calculator. It gives the required total and acceptance volumes instead of tank recommendations.
> 
> http://www.watts.com/pages/support/sizing_ET.asp
> 
> I think the amtrol ax tanks are asme rated. Which are $$$$$


 
Go with two tanks.  WAY cheaper.  I think my wood boiler was 55 gal. Plumbing added some.  Plus.. my original on the oil boiler was a bit undersized.  So... I went with the two.  No sense cutting it too close.

JP


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