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Inside vs. outside oil tank?

smoke02's picture

Hi to all, new guy here....


I heard a fact(?) the other day concerning oil tanks stored outside vs. tanks inside the home.  It was stated that an oil tank inside the residence would allow the home owner to install a different nozzle on their burner and would save money as the oil was now "warm". This, combined with the nozzle, would allow the heating system to work at a greater efficiency saving on heating costs.......I haven't been able to find any further info regarding this......can anyone shed some light on it?

(post #114942, reply #1 of 7)

I have to call a poo poo on that. My oil tank (1000 litres) is outside and gets cold (-45c this winter...aaaaaaaaaaaagh!)..however the feed line runs through heated space all the way to the furnace and by the time the oil gets there it is room temperature.
My oil supply run is about 40 ft through the basement (oil tank outside North wall, furnace at interior South wall) of heated basement.
fwiw :)

(post #114942, reply #2 of 7)

Thanks for the reply Kenora....I was startin' to wonder if this thing is turned on......:)


Do you happen to know what size of nozzle you have on the furnace?  Is it a high efficiency or mid range?  From the little I've been able to find out, the unheated oil is run through a larger nozzle due to its colder temperature.  The larger nozzle isn't as efficient as a smaller one and doesn't atomize the oil as thourghly causing "parasitic heat loss".  I haven't been able to find any hard numbers on bringing the tank inside as yet but the current heating bill is running approx. $380 per month.  The oil is running to a boiler system which feeds to an "in-slab" radiant floor  system.  The boiler is currently opperating at approx. 82% efficiency.


Any further info/suggestions would be appreciated....:)

(post #114942, reply #3 of 7)

Hi again; its an 82% efficient Lennox oil forced air furnace, its 12 years old. I don't know anything about the nozzle but can tell you Canada hasn't allowed oil tanks inside the house in decades so all us Can-knuckleheads heating with oil are in the same situation. I would suggest that you leave the tank outside (for safety) and if the tank is close to the furnace just run the pipe in a BIG loop so by the time it gets to the furnace it has warmed up. It goes through a small copper pipe (1/4 inch or so, maybe 3/8...not sure) but the oil doesn't flow very fast through that pipe and would have lots of time to warm up if the run was long enough.
My bill (to heat 900 sq/ft) for Dec and 1/2 Jan was $352. And that is keeping the temp in the place at 45 degrees f, since we aren't there except on weekends. OOOOOOOOOOOOUCH!

(post #114942, reply #4 of 7)

had my furnace and tank replaced 1 1/2 years ago here in eastern ontario


tank is in the basement if it was outside initial supply line has to be 2" black iron & you then have to run stove oil in it


these are provincial requiremets and all installations are inspected by a third party  &randomially by a  provincially appointed official

(post #114942, reply #5 of 7)

If possible I would put the tank inside. There are a lot of benefits, to name a few:


- No condensation.


- No risk of gelling


- Warmer oil will atomize better resulting in a better/cleaner burn


If you have to go with an outside tank you will need a two-pipe system. This will circulate oil that's not burnt back to the tank. The oil won't have time to warm up in the line as it goes through the basement. Besides, the new oil lines are plastic coated and will insulate them. You can however install a nozzle line heater that will warm the oil as it goes from the pump to the nozzle.

(post #114942, reply #6 of 7)

Some people around here have their tanks inside (basement) and some of them outside.  Ours are inside.  My mother's tank is outside.


No one that I know of with a domestic outside tank is running a two pipe system.  Single line, gravity feed. 


Feed lines are almost always 1/2" soft copper.  Frequently, any outdoor exposed portion of that around here is usually short (6' or less ) because most people keep those tanks pretty close to the house.



If the tank is outside, the exposed portion of that line will be problematic as regards gelling fuel when temps approach -10/-15 F....... unless........a heat tape is installed around the pipe, a heat lamp is hung over the portion of outside pipe to keep it warm or there is a blend of #2 & #1 fuel oil in the tank. Usually that blend would be 60% #2 and 40% #1.  This gets expensive because a gallon of #1 here this winter is currently 18% more than a gallon of #2.  And.... #1 has fewer BTUs per gallon than #2 does.  139,000 BTUs for #2 vs 134,000 BTUs for #1.   (This blend is usually only used around here for fills/deliveries after mid-December. Up till then, straight #2 should be fine.)


A heat tape or heat lamp is likely gonna be cheaper than a blend of fuel because you ony have to turn it on when temps are that cold.  But that heat tape or lamp will only save your butt to a certain point.  Once/if temps get really really cold ( -35/-40 F) for prolonged periods of time, I suspect straight #2  fuel can/could start gelling right in the tank. If the tank is on the south side where it can soak up some sun and painted a darker color that should help.


The advantages to having the tank outside would be that any spills or leaks are outside where they are more easily cleaned up, tank doesn't occupy space in the basement and it's easier for the fuel delivery guy because he can better see and hear what's going on as he fills the tank.


The advantages to having the tank inside have already been mentioned as have the disadvantages ( Leaks are inside, eats space and harder for delivery guy to monitor the filling process.  If the tank(s) gets overfilled, it will come leaking out of the gauge head on the tank and you'll be down there draining off a few gallons of fuel to put an end to that.  Plus you'll have some cleanup on the floor to do.  Point being.....if you have your tanks in the basement, make sure you don't order every last gallon that you think will fit in the tank.  If you're wrong and the delivery guy doesn't hear that it's time to quit and doesn't trip the nozzle fast enough, you'll have a mess to clean up. If you're going for dead full, be there when they deliver.  That or make sure you have a fill line whistle installed so he can hear when it's time to quit.)


As I said, our tanks are inside and that's okay with me. 


Edited 3/16/2008 11:07 am ET by HootOwl

(post #114942, reply #7 of 7)

I don't know about the better oil "mileage" but a tank inside or in a vault is better than being outside any day. We have a 4000 gallon tank in a lined vault. We ended up with thick oil issues (#2) and oil starveation issues on the boilers. BTW we are using a pump with return loop to the tank. The oil flowing to the manifold in the house about 150 feet away was so cold you could not keep a bare hand on the pipes.

We closed in the openings in the vault, lined it with 2" rigid insulation, and re-plumbed the manifold using tiger loops. That was the end of those problems. In addition, I added a remote temp sensor and the lowest recorded temp was 55.