Tandem oil tanks

John@Reliable

Use two inch pipe for crossover,11/4" fill pipe,11/2" vent.
Gauge and ventalarm should only go on second rec. tank once first tank is filled and crossover begins,ventalarm will tell system is full and still allow more for expanision,after fill both tanks will level out for room in both. Must use 1/2" on bottom supply. Picture shows 2" for all piping which is the way I like to do it,also swing joints on all piping, Hope this helps!

Jimi Les

tandem oil tanks

Could anyone steer me in the right direction on the web for info on oil tank hook-up's? I want to add a second 275 gal. oil tank to my existing 275, but not entirely sure how to pipe it. Been a plumber in NYC for 15 years, but with limited experience with oil. Gas heats best in NYC, but up in the boondocks of Connecticut where I now live, oil is the fuel of chioce. Any info would be greatly appreciated. Thanx

kevin

JIM..

Standard practice is to go w/ 2 (two) separate fills , one each tank,usually in 1.25". Then twin the vents together w/ a tee in 2". Now if you have an older system the vents might be in 1.25" or 11/2"... You make the call as to if it is a large enough vent. Tee the two bottom tappings together in 1/2" w/ individal shut offs and fireomatics. Good luck!kpc

Al_3

Tanks

The only diagram I've ever seen on this is to have one 2" fill into first tank, one 2" transfer pipe from first tank into second tank from top of both tanks, & one 2" vent from second tank to outdoors, used to be 1 1/4" on vent but think it has changed to full 2"------AL

Unknown

Thats how we do it

We also put swing joints on the crossover pipe between the 2 tanks , and use thread sealant on the inner and outer threads of all the joints .

Floyd

The 2\" fill..

with a 2" tranfer is the way I do it....
just make sure the transfer is lower than the fill.
And yes, I think a 2" vent is required most of the time now.
Just tee them together at the bottom and run one pipe to the
furnace or boiler, just make sure there are separate valves.

Floyd

Earthfire

oil pipe threads

no teflon tape on oil pipe threads, pipe dope only please. We use 2" pipe also common fill manifold and common vent, whistler in both tanks, The new oil trucks push a lot of volumne and need that 2"

Unknown

Yes - no Teflon

Our tank guys prefer to use that black Permatex . It wont leak on you , but youll have a hard time pulling the fitting apart again . And if it gets on your clothes , its on permamanent .

kevin

I know...

i have seen this crossover done a lot but I am not comfortable w/ it's arrangement. It is asking the 1st fill tank to bear the pressure for both tanks as it is filling the second tank. In "my minds eye" it is just asking for that tank to eventually rupture. Also, is it not easier for the oil delivery person to know when to stop if you have seperate fills? kpc

Alan R. Mercurio

Jim,I can't add much to what the guys have told you here tonight. But if you would like to see a diagram may I suggest you get your hands on an NFPA 31 Manual. Some times it helps to see what the guys are talking about.

If you can't get your hands on the Manual Please don't hesitate to e-mail me with a fax number I'd be happy to fax you the diagram.

Your friend in the industry,
Alan R. Mercurio
www.oiltechtalk.com

Unknown

To tell you the truth

When we replace a leaking tank in a 2 tank setup , we havent seen much of a preference which one leaks - the first one to be filled or the second one . Im guessing that when the 1st one is filled , and the vent works good , there might not be undue pressure on the 1st tank .

One question - do you need a separate gauge for each tank ?

kevin

ron...

yes I put a scully vent alarm gauge on each tank. I have never removed an old tank in a two tank set up but it is good to talk about it w/ those who have.I tend to err on the side of caution w/oil tanks because I have heard of too many oil tank spills/ breaks that involve the dept. of envir. protectn.... kpc

Bill NTSG

No Matter

Which method you choose, make sure both tanks are similar in size, and that the tanks are level and are at the same height. This will help the tanks to equalize. Do not tie the outlets together with rigid pipe. Use at least 1/2" od copper or use swing joints in case the tanks settle. As mentioned, valve both tanks, but I prefer only one filter. Tee the cross over line together and use one filter. If one filter plugs up and the other does not the tanks will not equalize. As much as I dislike the cross over fill method , it is the method described in the NFPA 31.

Floyd

Keep the crossover...

as low as possible and the vent full size and there is no way pressure can build.
also fluids will always seek its own level so if you pipe the bottom to a tee at the tanks and one pipe to the
furnace or boiler the level will always stay the same in both tanks.
You then always use a gauge with the alarm and vent off of that then when the last tank is full you will know it.
The gauge will always read the level of both tanks also.
I once piped four tanks together with a crossover from tank to tank with the vent/alarm in the last tank.
Worked GREAT!!!! Teed all the supplies together at the bottom.

Floyd

Jimi Les

Forgot to mention...

that the tanks are the type that lays flat ( sideways, whatever...) because they are under my deck. tanks have five 2" taps on top, the top being the broad, flat side ( vent, fill, feed, guage & crossover, I assume), and one 1/2" tap on bottom only. Bottom tap is currently plugged, and on top is a 2" bushing with two 3/8" taps with male X compression adapters attatched to the soft copper coil tubing that feeds the boiler (one adapter is plugged). And this feed rises from the top of the tank before traveling downward to the boiler, which is four feet below grade. How does the oil LIFT out of the tank to the gravity feed?

Floyd

Wow!!!!

Always got to make things difficult!!!! (G)
Under a deck???? HMMMMMMMMMM
Might be hard to get enough rise on the fill pipe then.
How much room do you have under the deck????
You may have to put a fill and vent with a separate gauge for each tank, then.
Also the pump will pill the oil up out of the takn and once it is primed it will siphon
so be careful if you take the end off loser than the tanks... the oil will still run out!!!
If you bring one pipe out of each tank and tee them at the top then they will still
pull evenly.

Hope this helps you.

Floyd

Jim_47

two tanks word of caution

I have seen disaster in the gauge when piping two tanks.
if you gauge both tanks in a series piped fill there is room for problems.
After tank A fills the crossover takes the oil to the second tank. If the cross over is higher than the gauge the gauge glass will also fill with oil (if there is a gauge in tank A) until the second tank fills there was enough pressure to burst the gauge. The oil company replaced the gauge vent alarm 2 times before I was called to look at the system. Customer was tired of the disaster. Ended up running two vents. the first one in tank A was just a 2inch vent alarm. The second vent in tank B was the 2in gauge/vent alarm package. This way you can still hear when the first tank is full and know when the second on is full.
Caution here is that you do not pres out the first vent!
I PREFER to fill into a TEE and then go into both tanks at the same time then seperate gauges and seperate vents. any way you slice it you own it.

Bob Bona_4

yes, never

put a gauge on the "fill" tank. I do twin tanks with one tank being the fill tank, with crossover, and the second tank is the vent tank. The vent tank gets the gauge. Swing joints everywhere. Equalizer on the bottom, 1/2" copper bent in a curly "Q", or pigtail shape to allow for tank movement.One of the tank valves gets a T to hang the filter off of.

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J.C.A.

Two tanks....

IMHO , piping tanks with a crossover fill system is BEGGING for trouble . NFPA says you can , but who here wants to be held liable for a spill when piping it right (2 fills,common vent and a gauge in each ((separate))! )would be far less prone to spillage?
Combination gauge/vents are , againIMHO a waste of time . When a combo float fails, the new gauge installed inevitably hits and sticks on the old sunken gauge .
There are 4-2" holes in the top of all tanks sold today. 1 fill , 1 vent , 1 gauge and a plug in case it needs to be pumped or serviced . Another point I should mention is that the 1/2 " tap on the bottom should receive a Bronze tank thermal valve . It is cast as 1 piece and is far less likely to leak compared to a 1/2X3/8 bushing ,short nipple,90, another nipple,valve and then a filter . The cost is more initially , but the piece of mind is worth far more than the money spent, for me. Doing anything like this is worth doing right , don't skimp . The insurance companies also like this setup much better .After seeing the cost of cleanup for a spill, you will too ! Chris.

J.C.A.

Thanks for posting the picture John

It makes my post that much more sensable . See the wet spots on top of tank#1 ? Pipe dope or anything else cannot stop the fuel from seeping out around the welded receivers on top of an oil tank . It smells up the joint and makes oil look unappealing as a fuel when people see this . Home inspectors will go after this like a moth to fire when they can't find anything else wrong in a home . Do it right and save yourself the problems .

JIM F.

oil tandem tanks

i use blue block on the tops of the tanks to prevent sepege. 2" fill and vent is required in ct. vent alarm and gauge on 2nd tank. 1/2 crossover on bottom with seperate fire valves

spl_2

gauge/vent alarm in last tank

Yes, in the last tank. I have seen gauges in both tanks, and what a mess it would make if the plastic vial on a gauge in the first tank broke or came loose while it was being filled. Even though different states go by different NFPA versions, the tank manufacturer typically specifies 2" vent, and that is what we do. A smaller vent will work fine volumetrically, but spider nests, pincher bugs, etc. cause too little margin for error.

J.C.A.

Goshdarnitt,

What's that dark spot around the fill on tank #1 ? I stand by my posts ! Chris.

JIM F.

seep[age

what your solution chris! after many many oil tanks installed blue block(i have found) is the best compound to prevent this. next step is what weld the fill and vent??

todd s

twin oil tanks

Jim, please take Alan Mercurios advice. There are some suggestions above which are not acceptable. NFPA 31 is the boss unless your local jurisdiction has stricter rules. I would also contact the fuel co. they should be helpful with this. A couple things to keep in mind: try to use swing joints between 2 tanks, I also like them on the transition from horiz.outside pipe to vert.pipe to tank. As far as oil lines go: soft copper,1-filter, and try to avoid overhead and two-pipe setups. If we run a new line over the floor we use a piece of aluminum threshhold screwed into the concrete. There are two channels which will accomodate 1/2od copper. Also MAKE SURE someone is inside watching tanks for the 1st delivery! good luck

J.C.A.

Jim,

My solution was explained .1 fill for each tank and a combined vent . If you remove the "spill" feature from the top of the tank , you won't get that seepage . The receivers ARE welded into the top of the tank . Therein lies the problem . Machine or man doesn't weld these "collars" tight enough to stop what is happening . With a vent whistle resting about 3 1/2 inches from the top of the tank , the whistles signals the driver to stop filling that tank when the whistle stops . (most of the time the bubbles will hit it first when fuel is being delivered at around 70 GPM)Therefore, the tank isn't filled to capacity , then relying on equalization to make things even . I don't want to get into a pissing contest , but after seeing every conceivable type of "spill and fill" install, I still believe that it isn't right . All the posted pictures prove it . 1 more hole in the wall,or however many feet of pipe you'll need isn't going to break you . Price the job accordingly and avoid A confrontation with the homeowner down the line . If someone undercuts you , sleep well knowing that the homeowner isn't calling you to do it over . (however, be prepared for a disgruntled homeowner to call you to do it right ). Again , the opinions expressed here are MY OWN . The NFPA doesn't agree with me but I sleep better at night knowing I did the job to the best of my ability and my concience is clear . Chris.

todd s

tanks

Chris I agree with you separate fill and vents are always better. another biggy make sure all piping drains toward tank, fuel laying in horiz. pipes eventually weeps through.

keith

O.S.V.

on the bottom of the tank on the branch of the equalizing line between tanks?

Mike Kraft

Theres another solution!

Try a couple of Roth Safety Tanks.Manifolds are manufactured approved easy and the key word is safe!I will bring the camera to the job tomorrow and take a shot of the steel tanks I recently installed.I might add I like the idea of a separate whistler and gage.I always use a combo but understand the reasoning now.Thanks!

cheese

Bob Bona_4

if the

tanks were pressure tested, the welds would prove to be tight. Some of the extra measures I take to ensure a leak-free joint are wire brushing the bungholes (the tanks were stored inside, natch ),doping the inside of the bungs, and the fittings, and hauling down hard with a 2 footer. I just switched to Mega-Lock, from #5 Rector. All seems well..

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J.C.A.

Bob,

I understand that tanks have been tested to 5psi . My question is still(after taking just 1 tank out of an incredibly small space about 14 years ago), how long does the code specify that the tank holds that 5 Lbs?
The 1 failure was in the most unbelievably small space that I think I had installed one until that time . Since then , the extra 25 minutes to plug, setup and pressure test a tank is indespensible . Granted , 1 failure in almost 18 years is extraordinary , but I still don't want to ever see it again . The tags sent on the tank now say to pressure test the tank prior to installing(usually a green backround with white lettering) . How often do you figure that happens? My best guess....almost never . Burn me once , shame on you . Burn me twice, shame on me . Capise? Chris.

Mike Kraft

Agreed

I test my tanks!Soapthe welds and screw joints.A real drag to find screw joint leaks or worse leaks on welds.But I agree with Chris and do test my tanks..........I dont test thee Roth Tanks:)

cheese

Bill NTSG

I hope

That there are undertank valves before the tees. God forbid if someone ever broke that union and could not get it back together and the tanks were full. Every one has a different method and a different way of doing things. I worked for a company that was in business since early 1900 and in the oil business since the 1920's. We did it "the way we always done it" Valve under each tank, a "non-rigid" cross over and one filter after the tee where the two tanks were twinned together. I have seen the filter on one tank plug on more than one occassion and the tanks not be able to equalize. I realize this can not happen with you application but my tired old eyes could not tell if you had a valve "under" the tank

Bob Bona_4

i hear you

it is always in the worst spot that there will be trouble! I had one leak on the end at the weld half way up..the installers musta forgot their compressor:)

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Mike Kraft

Pictures

of the job I'm on now.This is how I pipe them.I'm hate end to end tanks!

cheese

Bluenose_5

Tanks, tanks and more tanks

Wow, everybody does it a little differently.I'm from Eastern Canada and we have 2" end outlets available to
us.Tanks go on a common slab, fill is to the first tank, connect vents across the tops,teed together, whistle is second tank and separate gauge. Then 2" across the bottom,each with 2" valve, then union and tee(2*2*1/2"). Then firomatic,oil filter and osv.
Never a pressurization problem because of the 2" across the bottom, you fill both tanks as one unit.
If the 2" weren't available to us then I would go with two fills and vents.
I've used Roth tanks and they are pretty slick, but you have to be careful with burners that have pre and post purge if on a two line system(tanks may not have enough time to equalize).
Like I said everybody seems to do it a little differently, I've never seen the top connected for filling one then the other up here, don't know if it's allowed. Guess it's out to the truck to get the code book.

Bluenose_5

Bluenose_5

Tanks, tanks and more tanks.

Wow, everybody does it a little differently. I'm from eastern Canada and we have 2" end connections available to us.
So, here's my two Canadian cents worth( that's one cent American). Fill first tank, vents are teed together, one whistle in second tank, one gauge in second tank, cross connection is across the bottom with 2" black iron. Each tank has its own 2" valve. Teed off this bottom connection with a (2"*2"*1/2"),then firomatic, oil filter and osv.

Never any problem with pressurization because you are filling both tanks as one because its 2" across the bottom.
Those pictures look like Canadian made Granby and Kerr tanks.
Forgot to say if 2" bottom (end) connection weren't available would definitely push for separate fills and common vent.

J.C.A.

Cheese

I like the pads under the feet also ! The ones shown are nice but I always thread the bottom of the legs and put railing flanges on . Not only do you get the larger surface area to rest the Almost 1900 LBS/tank on , but it gives me yet another way of leveling the tanks due to floor irregularities .(two threads beat one anytime !) Chris.

J.C.A.

Cheese ,

Looks like a garage door hanger overhead . What will the powers that be make you put in front of those tanks to avoid a collision ?(if anything) I had one town wanted 4"lally columns , sunk 3 feet in the ground and cemented , another town was happy with the same columns just lagged to the floor . Yet another city wanted a knee wall made of cinder block. The rules used to change frequently and then town to town .Next year I hear that Ma. is going to NFPA 31 (bad move in my mind, we have far tougher standards and few safety problems).Chris

Mike Kraft

Chris..........

You seem very sharp on oil storage and sound like you have been to George Lanthiers seminars:) Both of these are very good things.The tanks are in a resy garage.There are no local codes or NFPA on barricading that I am aware of.Your concern is noted and very valid.These tanks sir paralell to the vehicles.But visions of a bumper hit are quite nauseating.I am going to read the regs momentarily.The inspector was in and never mentioned a thing.

As far as the tank legs........yes I have used floor flanges and threaded both sides.I don't anylonger.I find that a cut leg on the floor seem s"stronger"? in the long run?No steel is removed from threading.And this is where it sits on the floor.I keep lally column plates to use as shims and pitch mt tanks to the drain outlet.

And to our Canadian friend............I aint never seen a 2" equalizer.Interesting.Thanks for your 2 cents:)

cheese