Outdoor thermal storage?

[Carl Webber]

I was talking to a friend about my system and explaining to him how sometime in the future i was planning to add storage. I also posed to me that it was going to be difficult because i am limited by what i can fit through my bulkhead if i want to use pressurized storage. He suggested that i just buy some big tanks and bury them outside. I've hard many many people say that you can't do this but i have never heard anyone explain why. I searched this site and can't seem to find anything. If the tanks are buried at least 4 feet down so they are below the frost line then they won't be at risk of freezing. To get to them you could use the same insulated tubing that is used for outdoor wood boilers. As long as they are heavy steel and they are coated properly they shouldn't corrode. I'm sure that they could also be insulated and then fiber-glassed like some of the newer more efficient water heaters and that would not only insulate but also protect them from moisture.

Can someone explain to me why you can't have outdoor in-ground thermal storage?

 

[cityboy172]

Even if insulated / sealed properly, ground water/ moisture will be your enemy. Not to mention, it's not serviceable. Nope. No way I'd even think about it.

 

[tom in maine]

Remember who rules the universe. His/her name is Murphy and if you bury it, you WILL need to get to it sometime.
Murphy says so...
If you put it in an above ground building you can show it to people.

 

[peakbagger]

Sure it can be done but to do it right will cost several times more than the cost to have a custom fabricated tank that could be assembled in the basement. When it does fail, there is no option to fix it.I guarantee you one of American Solar Technics tanks will be heck of lot less costly reliable and quicker. I bought mine and drove the pieces home in the back of a pickup, carried them down the stairs and had it assembled and filling in about 6 hours completely solo.

 

[JP11]

My tanks, inside, spray foamed and dry. Two years in, I have a solder leaking on a bottom fitting.

I'd never make something with no access.

JP

 

[flyingcow]

Sure it can be done but to do it right will cost several times more than the cost to have a custom fabricated tank that could be assembled in the basement. When it does fail, there is no option to fix it.I guarantee you one of American Solar Technics tanks will be heck of lot less costly reliable and quicker. I bought mine and drove the pieces home in the back of a pickup, carried them down the stairs and had it assembled and filling in about 6 hours completely solo.

X2. And the heat transfer of the HX's is very good.

 

[goosegunner]

If you can't get them inside, how about adding a small room on a exterior wall somewhere? Like gable end of garage? You could get buy with 6' X 10' feet for two vertical 500 gallon tanks.

gg

 

[Carl Webber]

I don't have a garage or i would have considered putting them in there before burying them. We'll see how it goes, in the end i may just go with unpressurized storrage if that is the only thing i can get to fit in my basement. I have also considered trying to build a tank. I have noticed how my boiler is constructed and i think i could possibly build a tank out of 1/4 inch steel that would hold the pressure. Of course that would be my last resort as the tank would be large. i was figuring a reasonable size would 4x4x6 1/2. It would be about 780 gallons and once it is in there and built the only way to get it out would be to cut it up. The other thing i've considered is possibly building 2 or 3 smaller ones that would fit through my bulkhead and pipe them in succession. If i calculated right, a tank about the same size as my Tarm OT-50 would hold 300 gallons if it were just an empty box. If i could figure out how to fit a couple of those in my basement in succession i could get my 800 to 1000 gallons of storage. Of course that would require quite a bit of plate steel and i think that might get expensive. I've also considered opening up my bulkhead more. The doorway is about 34 inches wide but the actual width of the the bulkhead is about a foot wider. It would mean removing about 6 inches of foundation on either side of the door. I don' think it would be that big of a deal because it doesn't go to outside it just goes into the bulkhead, and i don't think it would have any real effect on supporting the house at it is only 6 inches. That could possibly be either cheap or free because i know someone that does concrete cutting and would do it for me. In the end that might be my best option because it means i would be able to get bigger tanks into my basement. Of course i'd have to ask someone with structural knowledge to be sure before going that route.

 

[maple1]

110 & 330 gallon propane tanks are 30" diameter. If that helps.

 

[GENECOP]

I am currently building my first tank, about 420 Gallons unpressurized , I am building it in my shop, mostly wood with steel and concrete.....I will take it apart and reassemble in the basement.....dimensions are 3'x4'x 5' tall....I have space restrictions as well, I can add one more of these next year giving me about 1000 Gallons total....

 

[Carl Webber]

110 & 330 gallon propane tanks are 30" diameter. If that helps.

Are the 330 tanks vertical or horizontal? Do you know how long or tall they are?

 

[GENECOP]

LP tanks can be oriented either Horizontal or Vert....

 

[Carl Webber]

i thought the vertical ones had a ring on one end to balance them on. Of course that could always be added after i get the tank too.

 

[GENECOP]

Before I decided to build I found a company that will set up either way...

 

[maple1]

Are the 330 tanks vertical or horizontal? Do you know how long or tall they are?

Mine are horizontal, 9' long.

The 110 I have is vertical, about 4' high.

But 110s could quite easily be laid on their side too.

 

[woodsmaster]

i thought the vertical ones had a ring on one end to balance them on. Of course that could always be added after i get the tank too.

The bigger ones don't come like that. People put those on so they can be stood vertical. i used truck rims to stand mine on.

 

[brant2000]

I have considered using underground concrete septic tanks. Obviously this would be an open tank and there would be a number of challenges and considerations to deal with. I think it could be possible, but probably not as economic as conventional tanks, unless you were looking at very large sizes.

 

[jeffesonm]

I have three 800L (211 gallon) tanks that are 30" diameter and <7' long I would sell you if interested.

 

[Carl Webber]

I have three 800L (211 gallon) tanks that are 30" diameter and <7' long I would sell you if interested.

Thanks for the offer but i'm going to have to pass for now. I just spent a bunch of money on installing a boiler and buying wood. I need to recoup some of the money I've spent before i think about spending more. Right now i'm just thinking about the future. Maybe 2 or 3 years down the road after this boiler has paid for itself then i can think about reinvesting the money on some storage.

 

[NE Properties]

I would have serious concerns about putting 1,000 gallons of glycol antifreeze treated water under ground. Nothing is forever. At some point there WILL be a leak and you are risking contaminating your entire property maybe even your drinking water if your on a well,

 

[Carl Webber]

if everything is below 4 feet in the ground would you still need to use glycol? I was only thinking about the possibility of doing it without glycol. I do agree with you that i'm risking a lot if it has glycol. I would definitely not do it with glycol in the water.

 

[Fred61]

Buried storage is a bad Idea and I would avoid it at all costs. All you need is one small contact of moisture and it will wick away your heat at warp speed never to be recovered.

 

[Carl Webber]

What about in a shed? I have a shed that is about 16x16. Could i run lines out there and install the tanks out there safely, or would i lose too much heat getting the hot water out there?

 

[Fred61]

Better than burying a tank! Use the best insulated underground tubing.

 

[Tennman]

After running without storage for 5 seasons and now with it.... Add storage as soon as possible. You're much further north than us so you shouldn't experience as much idling as we did. But the benefits are too numerous for me to type with an iPad. Besides finally allowing the boiler to run like it's supposed to, the biggest thing you'll learn not having storage.... It's like having a house dog.... It sets your schedule and you plan your day around the boiler, and middle of the nite bridging, or the dreaded FUEL message. And unfortunately that schedule is a moving target based on the weather. Had I known then what I know now, I would have made sure we had storage 3-4 years ago.

Energy loss via conduction would be terrible for a septic or underground tank unless you were a millionaire and could insulate it properly. Absolutely in the shed, above ground and as soon as possible. I hope you have well easoned wood for your first season, it makes learning the beast so much easier. Blessings and you've found the right place. The guys here were my lifeline 6 years ago.... Still are.