# Is anyone using 275 gal. oil tanks for water storage?



## Richardin52 (Nov 7, 2013)

Thought I would put four in side by side standing on end. They would be all taped for gravity feed from the boiler that way. Figured I would pick up some used ones, steam clean them and pressure test them then set them on styrofoam and insulate them.


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## ewdudley (Nov 7, 2013)

This comes up two or three times a year.  Opinions vary from "why bother" to "hell no".

However it's conceivable that a cylindrical tank with reinforced ends could work in a system with an open cistern expansion vessel.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&cad=rja&ved=0CHAQFjAF&url=https://www.hearth.com/talk/threads/storage-tank-options.107385/&ei=0GV7UpqZI8apkAfjhYDIAg&usg=AFQjCNHyNR0lRAGPZQqVBgkCXvyTdG_ZIA&sig2=KwpWkw8n8UAzTP4qIuEfaw

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=8&cad=rja&ved=0CIABEBYwBw&url=https://www.hearth.com/talk/threads/oil-tank-for-hot-water-storage.46597/&ei=0GV7UpqZI8apkAfjhYDIAg&usg=AFQjCNFei72KtK2iblB0mnDCGXTZqpOiww&sig2=DRrClf_y8HmxU2IJbVQw4g


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## jebatty (Nov 7, 2013)

My first self-install used 3 used oil tanks for non-pressurized storage, plumbed in series, insulated with fiberglass. First observed problem was not getting them clean enough, lots of crud showed up in the hot water from the boiler which probably did a better job of cleaning the tanks than I could do. Lots of other problems related mostly to my lack of knowledge in plumbing a hot water boiler system. As an open system, give consideration to appropriate water treatment to prevent corrosion. 

Although you say you will pressure test them, keep in mind they are not pressure tanks and must be vented to the atmosphere. If you plan on feeding hot water to points above the tanks and a vent at a higher location and not the tanks, the pressure in the tanks will increase, and they are not designed for any more pressure than the weight of fuel oil in them.

I would be wary of mounting them on end. 275 gal of water weighs about 2300 lbs vs same volume of fuel oil weighs about 1980 lbs, and the tanks are designed to handle the weight in a horizontal position. The change in position alters the pressure distribution and there is a heavier fluid. The tanks may be subject to bursting initially or from metal fatigue as time goes on. Check this out. Bursting could be catastrophic.


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## Richardin52 (Nov 7, 2013)

jebatty said:


> The tanks may be subject to bursting initially or from metal fatigue as time goes on. Check this out. Bursting could be catastrophic.


 


 Not sure what you mean by metal fatigue over time leading to bursting. If I pressure test the tanks outside using water and a small amount of air to get the pressure up it would be very safe because water will not compress so any leaks would be just that, no bursting or at least no problem other than a pop and water flowing sorta like a garden hose. 

If the tanks are pressure tested I would then know if they could stand the pressure they were tested at. If they were in service and did start to leak they would act just like any a boiler or hot water heater that started leaking. In other words a pin hole and a leak.  I do not see bursting as a problem.  Can you explain.


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## jebatty (Nov 7, 2013)

Nothing to add. Read the other comments and links. They may work for you. For me I would never do it.


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## peakbagger (Nov 7, 2013)

Heating oil tanks are generaly rated at 1 psi so they can only be used in vented system. Getting them clean will be difficult unless you have access to a steam cleaner. With a vented tank, you will have accelerated corrosion in the vent space. Theses tanks used to be standard on the Madawaska wood furnace installs and many failed over the years and were the reason that many of these furnaces were removed (550 gallons of rusty water in the basement tends to do that).

Overall, don't do it.


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## JP11 (Nov 7, 2013)

Walk away!  Find another idea.  You're "savings" isn't worth it.

JP


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## 700renegade (Nov 7, 2013)

If they are truly gravity only, personally I don't see a problem with bursting or change of position.  they are a uniform ( thin ) wall thickness and don't deform from standing on those 4 narrow welded angles near the bottom - standing on the end shouldn't be a deal breaker.  Initial cleaning may be your biggest problem, next would be propensity to leak since the metal is so thin and it won't take much for a pinhole to develop.

If the space they are going to sit in is rough like an old Maine farm house perhaps a leak is not catastrophic.

Don't plan on much of a service life though.

There have been discussions from guys using stick built frames and EPDM liners, spray foamed septic tanks and numerous other schemes way crazier than a steel fuel oil tank


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## kopeck (Nov 7, 2013)

700renegade said:


> There have been discussions from guys using stick built frames and EPDM liners, spray foamed septic tanks and numerous other schemes way crazier than a steel fuel oil tank



Stick built frames and EPDM liners are common, not sure I would add them to the crazy list.

I wouldn't oil tanks, at best they're temporary.  The trick is getting rid of them before they become an issue.

K


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## tom in maine (Nov 7, 2013)

Using a used oil tank is downright scary and fraught with potential problems. At very least, you need to have new tanks. Even then,corrosion is going to be an issue.
If it is to be an unpressurized tank, treated with corrosion inhibitor, the water/air interface will corrode.
They are just not thick enough for pressure or worth the risk.
If you are on a tight budget, use a stick built tank with pressure treated wood, stainless steel fasteners and an EPDM liner.


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## rowerwet (Nov 7, 2013)

corrosion won't be an issue with proper water treatment, I ran a vented pellet boiler for years with no rust issues as long as the water was tested each season and balanced after the system was filled. 
the oil tank idea might work if they are used as designed, on their feet, on end,  I can't see the welds in the thin metal standing up for long.


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## Gasifier (Nov 7, 2013)

Richardin52 said:


> Not sure what you mean by metal fatigue over time leading to bursting. If I pressure test the tanks outside using water and a small amount of air to get the pressure up it would be very safe because water will not compress so any leaks would be just that, no bursting or at least no problem other than a pop and water flowing sorta like a garden hose.
> 
> If the tanks are pressure tested I would then know if they could stand the pressure they were tested at. If they were in service and did start to leak they would act just like any a boiler or hot water heater that started leaking. In other words a pin hole and a leak.  I do not see bursting as a problem.  Can you explain.


 
Water flowing sorta like a garden hose is nothing you want, and then have to fix. They would not act like any boiler or hot water heater that started to leak. They have 275 gallons of water to leak instead of ...... What does your boiler have in it for water? 30-60 gallons? Now if they are all hooked up together and leak? Then you have to drain them, but first pull the insulation and whatever else off of them, and you certainly won't want to try to weld and fix them knowing that one of them will leak sometime soon again.

I'm with some of the others. I wouldn't do it with the oil tanks. Not worth it.

Keep your eyes open for used propane tanks if you are looking for the least expensive option. Used air receiver tanks would be next. These are great because they are clean, all set up for fittings already, and already have a stand on them. Watch equipment auctions, farm auctions, garage auctions, craigslist, ebay, etc.,etc.


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## TCaldwell (Nov 8, 2013)

I did it with 2 275 gal oil tanks piped in series to the garn. The tank mfg claimed they are sold as good to 5 psi, most will blow before 9 lbs, I had a adjustable relief valve at 7 lbs. Luckily I had no incidents but removed after 1 year, not one of my smarter moves and would not want the angst again.


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## mustash29 (Dec 8, 2013)

I recall reading this thread.  I just came across an interesting little video, pretty cool that an atmospheric tank design is this tough.  I'm not saying it is ok to pressurise it or use it for pressurized storage, but I was impressed at it's capabilities in taking the punishment they dished out.

Grandby oil tank video:


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## altmartion (Dec 8, 2013)

I think water would rot the tank fast. it would need to be extensively cleaned and then coated. why do you need so much storage?


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## ArborAirs (Dec 8, 2013)

Boiler Greenhorn here. I just installed my first boiler, Classic 6048 heating 2160 sf house, domestic and 3200 sf shop via air exchangers. Planning to add pool, hot tub and possibly another 3200 sf shop. Fired up a month ago when temps were 20-30 degrees. Wood was cut through out spring and summer and is not split so not green but not as dry as it should be. Boiler instantly got caked up with thick creosote (black tar). Likely from the poor wood and loading techniques. I load up in the evening and sometimes come out in the morning to empty firebox and 150 degree water temp. I was thinking about adding water storage for longer cleaner burns and to buffer the water temp swings. Also I believe this would benefit greatly in the shoulder seasons and summer only burning every few days instead of smoldering. Just for trial and test to see benefits before I build a monster tank I am thinking of plumbing in 2 265 and 1 300 gallon fuel tank. I don't see a problem with it. I have a crawl space where I could put a 4000 gallon storage tank if this turns out to be beneficial. Main reason is so I don't have to worry about babysitting the fire so much. Comments?


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## ArborAirs (Dec 8, 2013)

Also, my dad has a 265 standing on end sitting on a small few blocks because of convex end full of used motor oil for a few years now. Working fine, just fine. So what is the ultimate storage tank material and design? stainless? Plastic?


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## altmartion (Dec 8, 2013)

why so much storage? that needs a lot of btu to maintain that much water. what are you heating?


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## ArborAirs (Dec 8, 2013)

May not necessarily need 4000 gallons. From what I've read, storage will allow me to let the fire die if I leave for the weekend or don't make it home at night to keep it fed. Once the water is heated maintaining shouldn't be an issue with good insulation. Also storage will be inside shop so any heat leaked is just heating the shop.. I'm just asking all of you. Storage good? how much? and how to build?


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## altmartion (Dec 8, 2013)

ArborAirs said:


> May not necessarily need 4000 gallons. From what I've read, storage will allow me to let the fire die if I leave for the weekend or don't make it home at night to keep it fed. Once the water is heated maintaining shouldn't be an issue with good insulation. Also storage will be inside shop so any heat leaked is just heating the shop.. I'm just asking all of you. Storage good? how much? and how to build?


storage CAN be good. but it has to be sized properly. you need to make sure you have enough btu to heat all that water efficiently.  the more water you have the more stand by loss you can have.  the reason for storage is to save energy. how about a load calc? have you done one yet?


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## ArborAirs (Dec 8, 2013)

no. How do I do that?


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## BoilerMan (Dec 8, 2013)

ArborAirs said:


> Also, my dad has a 265 standing on end sitting on a small few blocks because of convex end full of used motor oil for a few years now. Working fine, just fine. So what is the ultimate storage tank material and design? stainless? Plastic?


Ultimate storage material/design:  Used propane tanks which share boiler water so no exchange losses.  The more insulation around the tank the better.  Some use spray foam ($$$$$) I'd be inclined to build a stud and plywood box with a minium of 24" from any point to the tank then fill it with cellulose insulation, stuff some roxul in first and some blue board on the outside.

TS


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## ArborAirs (Dec 8, 2013)

I like the sound of that. (Propane tanks) I can probably fit 2 500s in the space.  Is that too much? Cellulose sounds good. Cheap and easy to remove for service. How much do they cost? What's the best way to buy them?


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## tom in maine (Dec 8, 2013)

Just a clarification on heat exchangers.
They lose nothing. They are not 100% efficient (although they can be quite excellent), but that does not mean you are losing heat. You might have a circulator run a couple minutes longer to exchange the same amount of energy as if it was not there


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## e-zlight (Jan 23, 2014)

Old propane tanks can be bought for $1/gallon. I know a guy here in Maine that bought a 1000 gallon propane tank, and buried it in the ground surrounded by insulation & such, piped it all to a outside wood fired furnace. Only has to fire up the furnace every 5-6 days to heat all the water in the tank for his house. pretty good if you ask me. Kinda a cross between geothermal & the wood fired furnace.


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