Oil tank spill

mysavior

I had both of my tanks fill and the main one is filling up and spilling to the top, I think my oil guy might have fill it up too fast. The problem is it goes down when I turn off the heat and once I turn it on it goes back to the top. I have (2) 275 gallon tanks. Any advice would be greatly appreciated.

Intplm.

I cant see the leak or spill.
What I do see is two tanks twinned together with one vent. That is probably the problem you are having. In your case you should have a separate fill for each tank as shown in the pictures and two separate vents. The vent alarms will be able to work more effectively when they are piped with separate vents for each tank. That should stop any over filling and spill over issues you are having.

Also. Why are the vents piped like that?
They should be separately vented. One dedicated vent for each tank.
And why are they piped with plastic PVC pipe?

This is amatures.

The vents are piped terribly wrong. The vents need to be re-piped with the same material as the fill pipe. #40 black malleable pipe, and separately!!!

Jamie Hall

Oy. All of the above, plus -- what is the MacGyvered line going into the top of the tank on the right?

I hope this wasn't set up by your oil company or tech...

HVACNUT

All of the above, plus it looks like it's drawing from both tanks but returning to only one. Hence the flare Tee with the cap. Real genius.

What's wrong with gravity feed to the burner(s)?

And the PVC venting. 🤮

STEVEusaPA

What @HVACNUT said. Piped wrong and illegal, especially the pvc venting, a real dangerous situation in the event of a fire.
I’d switch out the vent pipes to steel, put the supply back to a one pipe, put in the bypass plug, add an OSV...make it right, legal and safe.

mysavior

I bought the house like this. I have been here for 13 years and never had a problem until now. Should i hire the oil company? or use my regular boiler guy to correct this problem.

EBEBRATT-Ed

@mysavior

There's nothing wrong with a common vent, that's been done for years with no problem provided the vents are pitched properly and those vents may not be pitched properly. You can have 4 tanks with one common vent.

The PVC pipe is another issue most likely done by some idiot and the vents need to be redone.

As far as the oil level in the tanks go they will always equalize across the bottom. It's a two pipe system going to the oil burner and it makes no difference which tank the return line goes to.

If you oil levels in the tanks are not the same there is only 2 possible problems. One tank has a bad gauge or the bottom equalizer pipe between the tanks is plugged.

STEVEusaPA

mysavior said:

I bought the house like this. I have been here for 13 years and never had a problem until now. Should i hire the oil company? or use my regular boiler guy to correct this problem.

If you've been there for 13 years and no one pointed this out to you, I’d trust neither.

EBEBRATT-Ed said:

There's nothing wrong with a common vent, that's been done for years with no problem provided the vents are pitched properly and those vents may not be pitched properly. You can have 4 tanks with one common vent.

I know of no code that would allow 4 tanks in a residential setting, 2 max tied together, 3 tanks or 660 gallons-If you want to follow code.

EBEBRATT-Ed said:

...As far as the oil level in the tanks go they will always equalize across the bottom. It's a two pipe system going to the oil burner and it makes no difference which tank the return line goes to.

If you oil levels in the tanks are not the same there is only 2 possible problems. One tank has a bad gauge or the bottom equalizer pipe between the tanks is plugged.

I think in this case it’s very possible that if both tanks were completely filled, and your favorite, 2 pipe, is pulling 17 gph out of both tanks and returning the bulk of it back to one tank, it wouldn’t equalize fast enough.

mysavior

Thank you very much for your advice. I will have it checked out. Very cool forum.

EBEBRATT-Ed

@STEVEusaPA

Don't know about NFPA but MA. will allow (4) 330 gallon max in any building unless something has changed recently.

As for the (excellant) 2 piper if the return goes to one tank as it does in this case the burner will mostly draw from that tank that has the most oil in it so it can't ever overfill either tank

dopey27177

Either both tanks should be piped separately or they need to be twinned top and bottom where they will work as one tank.

Jake

STEVEusaPA

@EBEBRATT-Ed I double checked. NFPA 31 does allow up to 4-330g tanks, but only 2 can be tied together. Can't gang 4 vents together. Must have 2" crossovers. All four can be ganged together on the bottom.
All 4 tanks (or multiple tanks) must be on the same slab and same height if supplies are ganged together.
As far as your theory on the return piping, my brain sees them drawing equally, but dumping the return only in one. I don't see them leveling back off fast enough.
Another reason I'm not a 2 piper

HVACNUT

> @STEVEusaPA said:
>
> As far as your theory on the return piping, my brain sees them drawing equally, but dumping the return only in one. I don't see them leveling back off fast enough.


I can't wrap my head around that either. If both tanks start out full, the fuel pump moves 3 GPH drawing 1.5 GPH from each tank.
Say the burner is firing at 1.00 GPH.
2 GPH is dumping back into one tank so its actually refilling .5 GPH more than its drawing.
No?

I don't know if it's correct or not, (followed company direction) twinned tanks, 1 or 2 pipe oil lines, we always filled one tank, vented the other using a 2" crossover.
Oil lines would be exactly equal at the Tee(s).

STEVEusaPA

To take it one step farther, what if one of the oil lines coming out of one tank gets restricted/partially restricted, either from gunk or filter plugging?
Another reason why I use 2 separate fills and ganged vents on all tanks (especially Roth tanks), with single oil line, and maybe (rarely) a Tiger Poop.

EBEBRATT-Ed

@STEVEusaPA & @HVACNUT

I agree a plugged line could screw things up. Picture both tanks half full or full for that matter and equalized at the same level.

So let's say the burner fires 1 gph and the pump moves 3 gph as above.

In 1 hour of run time the burner pump pulls 3 gph and at the start it pulls 1,5 gph from each tank, 1 gph goes through the nozzle, 2 gph returns to tank 1.

This causes the level in tank 1 to rise because your returning 2gph to it and only taking 1.5 gph out of it

Because the level in tank 1 rises now the tanks may be slightly unequalized with tank 1 higher than tank 2

Because tank 1 (the one with the return) is at a higher level as the burner continue to run it will take more oil out of tank 1 because that tank with a higher level is exerting more pressure to the bottom equalizer than tank 2 so now for example our pulling 2 gph from tank 1 and 1 from tank2. Plus as soon as you return to one tank only its'level rises and it starts to equalize.

EBEBRATT-Ed

@HVACNUT

MA. used to require either seperate vents or a common vent for multiple Tanks.

About 30 years ago they approved the 2" cross over fill on 1 tank and vent on the other.

I never installed it that way to me the truck pump pressure which me be 50 psi or more can get exerted on the first tank while the oil is crossing over to the second tank. But it is approved and saves on piping. I just don't like it.

EdTheHeaterMan

@HVACNUT said: I can't wrap my head around that either. If both tanks start out full, the fuel pump moves 3 GPH drawing 1.5 GPH from each tank.
Say the burner is firing at 1.00 GPH.
2 GPH is dumping back into one tank so its actually refilling .5 GPH more than its drawing.
No?

if you are correct then @mysavior would not be having the problem. I'm wondering how much oil is moved from the pump gearset on the pump at @mysavior 's home.

according to Suntec information, the A2VA 7117 fuel pump gear set moves 17 GPM so... that would be 8.5 GPM from each tank assuming they are no blockage in the bottom cross over and after burning 1 of those gallons the fuel pump would return would 16 GPM to one of the tanks. If the burner operates for 30 minutes... and the fuel supply crossover is partially plugged on the tank with the return line... then there is 6 or 7 gallons more in the tank with the return line and less on the other tank.

now if this never happened before then there is a simple explanation. 1. the fuel line just (all of a sudden) found 13 years of tank bottom deposits partially blocking one side of the cross over piping. AND/OR 2. The tanks were never overfilled before and this is the first time in 13 years the oil has reached that level.

Remember the oil driver does not have x-ray vision... only an ear for the vent alarm.

Question for HVACNUT: What fuel pump has a gearset capacity of 3 GPM?

EdTheHeaterMan

followup:

me forgot to say:

PVC Vent BAD!

metal vent pipe GOOD