Size expansion tank for 1000 gallon storage?

[maple1]

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.

 

[dogwood]

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

 

[dogwood]

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

 

[rkusek]

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?

 

[BoilerMan]

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

 

[Armaton]

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.

 

[mikefrommaine]

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

 

[mikefrommaine]

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.

 

[maple1]

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.

 

[mikefrommaine]

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 $$$$$

 

[JP11]

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