Converting Propane Tanks to thermal Storage.

[warno]

Here is how the flow runs through my tanks.

And here you can see my supply and return headers. My headers are 3" pipe. Each with 3) 1" connections.

And the water flows from tank to tank via a 2" 90° elbow that couldn't have fit better in its location.

I built the stack laying on its side on my garage floor then stood up the bottom and middle tank as 1 unit and set the top tank on top while in location. I had my father help with a skid loader for all that. It was fun considering my stack is 93" tall and my garage ceiling is 96". And yes I did later box in the stack and insulated everything.

 

[sardo_67]

wow, very nice, i just wish i could fine tanks like that used around here in CT or even within a 2hr drive. all i find are new ones for like 1100+.

i have 2 500 gal tanks now but they had diesel fuel in them for years, i cut one in half, cleaned it and tonight i am going to burn it clean, then stand them up on end and weld a flat piece on the open end making two 250 gallon tanks that will fit into my basement. giant pain in the ass but it's all i have for options right now unless i drop thousands on other tanks.

i think 500 gal in 2 tanks plus the 55gal my HS tarm holds would be enough for my house, only 1600 sq feet and a 24x24 insulated garage with a 60k BTU modine heater, my goal is to run the boiler only once every 48-72 hours

 

[warno]

I think you are going to need to burn alot more than every 2-3 days. I've got 750 gallons of storage and only heating a 21ft x 24ft garage and I was burning twice a day in the dead of winter. I mean the garage isn't fully insulated in the ceiling but still. I could go from 180 to 140 in 12 hours time in my storage.

Also if you are putting a flat bottom on your storage tanks I hope they won't be pressurized. A flat bottom that big without stay rods will bulge out with less than 5 psi. Flat plate doesn't like pressure.

 

[maple1]

I need to burn for 6 hours each day. With 660 gallons.

Edit: and yes be very careful what you do to your tanks if there will be any pressure at all in them.

 

[sardo_67]

I think you are going to need to burn alot more than every 2-3 days. I've got 750 gallons of storage and only heating a 21ft x 24ft garage and I was burning twice a day in the dead of winter. I mean the garage isn't fully insulated in the ceiling but still. I could go from 180 to 140 in 12 hours time in my storage.

Also if you are putting a flat bottom on your storage tanks I hope they won't be pressurized. A flat bottom that big without stay rods will bulge out with less than 5 psi. Flat plate doesn't like pressure.

i didn't thing about that, would a cross with angle iron be enough to hold it? they will be a pressurized system. I am going for this here in the attached pic, 2 tanks with my boiler and current oil boiler to run as needed either when not running the wood or fall/spring time when it's not cold enough to run the wood.

you were only heating the garage with that storage? what temp were you going for and what was your heating source, radiant or a Modine type?
my garage will be set at 40* unless i am working in it and i also have a wood stove that i'll be running if i'll be in there all day or for an extended amount of time.
if heating is just too much then i'll have to stop heating it till i fully insulate the roof.

as for burning i'll see what happens, this is my first winter with a wood boiler so i'm sure there will be a steep learning curve, i am not expecting it to be that efficient right away but my end goal is to dial in the system so that i can feel it once a day or less.

 

[maple1]

Not sure anybody here can or will say that this or that is OK to do when it comes to cutting & welding an LP tank & changing its configuration. I know I won't - pressure vessels are engineered to stand the pressure. And the ends are rounded for a reason.

You can get a rough idea how long your storage will last between burns with a bit of math. 1 BTU is one pound of water one degree F. Work that math out using your tank capacity and high/low useable temps and compare to the heat load of your space. Which might need a heat loss calc - which there are online calculators for. I figure my 660 gallons stores about 225,000 useable BTUs, depending how hot I charge them. That's not much heat loss spread over 24 hours. Even 20,000 btu/hr is a pretty low figure - so mine would only get about 12 hours +/- with no fire at that load.

 

[sardo_67]

i have seen that before, does tank insulation come into play at all?

or does most of the cooling come from sending the hot water tru the heating devices in the house?

 

[maple1]

Your house needs heat. It would come from the boiler or tanks. And tanks only hold so much heat.

 

[airlina]

I burned my Econoburn boiler for 5 years before I realized the advantage and convenience of adding storage to my system. To help me in this pursuit, I enlisted the help of these guys at www.hydronicspecialtysupply.com to do the transformation on a 500 gallon used up propane tank I found at a local suppliers yard. I transporter the tank to them and they took it from there. Pictures tell a better story than I can, so I will let them do the talking. The completed tank has performed very well since installing it in my system and I now can utilize my wood boiler the way it was intended.

 

[sardo_67]

I burned my Econoburn boiler for 5 years before I realized the advantage and convenience of adding storage to my system. To help me in this pursuit, I enlisted the help of these guys at www.hydronicspecialtysupply.com to do the transformation on a 500 gallon used up propane tank I found at a local suppliers yard. I transporter the tank to them and they took it from there. Pictures tell a better story than I can, so I will let them do the talking. The completed tank has performed very well since installing it in my system and I now can utilize my wood boiler the way it was intended.

oh wow! are you selling that on CL right now? i saw a dual 500gal tank system on there last week out in mid/western NY.

my issue is the idiots who built my house made the ceilings 7ft 3 or so, basement as well which greatly limits my storage capacity, plus my house isn't that big to begin with and horizontal 500s won't even fit into my basement thru the bilco doors. hence why i was going to cut these down.

then i made the mistake/ran out of patients and bought 2 tanks that had been used for fuel storage for decades.

i am in CT and can't find anything unless i buy brand new at over $1,000 per tank, all of the gas places near me won't sell out of date tanks, the scrap yards near me won't sell the scrapped tanks as i need a scrap license. this is all becoming very aggravating.

I started burning the tank i opened up to clean it and it has worked well i will see about shortening it then rewedding it so i have the correct rounded ends then use vertically.

 

[maple1]

Have you checked out American Solartechnics tanks? They are modular. A break down box that you assemble then line with a liner. It's an open tank but you can use heat exchanging coils for your pressurized system. I think they can build a tank/box to fit your space.

I am quite sure my 330s would fit into that space also. Or mutliple 100's.

 

[salecker]

then i made the mistake/ran out of patients and bought 2 tanks that had been used for fuel storage for decades.

I don't think you made a mistake getting those tanks.The residual fuel in them is easy to clean,you have to alter them or any tank to fit in your space.You got them cheaper than your alternative.
A little elbow grease and you will be good to go at a fraction of the cost.
I got old propane tanks and they needed to be cleaned on the inside as well.10 min with a pressure washer did the trick.
As for cutting and welding the tanks,others have done it.If you are standing the tanks on the flat end that you are welding on that should help with the pressure against the flat plate.If you are worried about the chance of it bulging,go to a scrap yard and find some 1/2" plate to use as the new bottom,or thicker,add some cross bracing like you said,and i would be satisfied if it was going in my basement.

 

[maple1]

Seems I remember reading somewhere on here sometime before about someone cutting the end off their LP tank, then flipping it over & welding it back in again. So the curve was inside the tank. Then they stood it up on that end. That was a while ago & don't know how it worked out, and it likely added way more stress to the tank where it was welded back together than the original tank design resulted in, with the curve like that. But may have still been OK? Need to be very competent & thorough with the welding for sure, however, no matter what the reconfiguring is that's being done. I was also thinking from the other pics you posted that they looked thinner walled than typical LP tanks, but can't really tell by pics sometimes.

 

[warno]

Seems I remember reading somewhere on here sometime before about someone cutting the end off their LP tank, then flipping it over & welding it back in again. So the curve was inside the tank. Then they stood it up on that end. That was a while ago & don't know how it worked out, and it likely added way more stress to the tank where it was welded back together than the original tank design resulted in, with the curve like that. But may have still been OK? Need to be very competent & thorough with the welding for sure, however, no matter what the reconfiguring is that's being done. I was also thinking from the other pics you posted that they looked thinner walled than typical LP tanks, but can't really tell by pics sometimes.

I remember that as well, but also can't remember who did it or the end result. It's on here somewhere though.

 

[sardo_67]

after looking at stuff i am going to use both thanks and shorten them by re-welding the rounded end on the shorter body bringing the OAL of the tank with legs to 6ft even leaving me about 12" of clearance in my basement for insulation.

 

[jeffesonm]

Sardo - A bit of a drive but there's a guy just north of Philadelphia who sells 220 gallon tanks for $150 each. I bought a few to use for storage but never got around to installing my boiler. More info here Looking for some input on storage

 

[sardo_67]

Sardo - A bit of a drive but there's a guy just north of Philadelphia who sells 220 gallon tanks for $150 each. I bought a few to use for storage but never got around to installing my boiler. More info here Looking for some input on storage

yes i found those as well, however it was AFTER i got my tanks, plus those are 1/2" thick and almost 1,000 pounds.

I'm not thrilled with the tanks i have but i'll have to make them work

 

[sardo_67]

did someone here say they have a PDF file on how to calculate the exact volume of the a tank that has been cut down or modified?

 

[warno]

Just do the math on what you cut out.

3.14 x R^2 x length cut out in inches. Then divide by 1728 and multiple by 7.48. This will give you gallons removed from your tank.

So if your tank was 30" round and 6 feet long and you cut out 24".

3.14 x 225 x 24 = 16,956

16,956 ÷ 1728 = 9.812

9.812 × 7.48 = 73.39

So that would be 73.39 gallons removed from your original tank if those were your measurements.

 

[sardo_67]

oh hahah ya i didn't think about that, i was on google doing conversions and cubic inch conversions on the dome ends when i could have just done the area of the section i REMOVED......

ya my tanks are 280-300gal tanks.

i was over thinking that, my bad