Oil tank and oil burner type furnace are on same basement floor level. It’s a single 3/8″ copper feed line from tank to burner. It has been in operation for 5 years with no problems thus far. The oil level is always kept to half full or more.
The BOTTOM of the tank is approx 8″ up off the floor.
The oilburner is 24″ up off the floor to the CENTER.
This means that when the tank is only 1/3 full, the oil level is EVEN with the burner.
The question is; if the oil level gets any lower than this 1/3 , will the burner still be able to ‘draw’ or ‘suck’ oil into it, or will it just draw air? (no oil)
Obviously, when the tank is 1/3 full or more, the oil will flow under gravity influence,and will also be assisted by the burner’s pump. But will the pump be able to accomplish this if the oil level is somewhat below the burner.?
I know that if a tank is installed a certain level below the burner that a 2 line system (return) is needed. This installation is not in the 2 line category.
It would be nice not to have to maintain this 1/3 or more level for fear of running out, or ‘sucking’ air.
Any input would be appreciated.
Thanks.
Replies
Hube,
If I am correct, the outlet for the tank is at the bottom, isn't it ?? Thats how mine is. It may have a slight riser pipe inside (may be an inch or so ? ) to keep the inlet out of the "crud" that accumulates at the bottom of the tank, but as long as the fuel level is above the inlet pipe, it cannot suck air, as there is no air at that point. The pump on the burner will pump oil as long as the inlet tube is covered.
Bill Koustenis
Advanced Automotive Machine
Waldorf Md
Mr bill; thanks for the reply... I may have put the words "suck air" in and mislead the problem. I agree as long as the intake tube is in oil, then no air can enter the feed line....I think what I'm really concerned with is whether or not the burner's pump is able to "lift the oil when the tank's oil level gets down below a third full.level or less....IF the oil in the tank ever is allowed to get down below 1/4, would the burner pump be able to make this lift of approx 18 inches without any faltering?
This is what I am really asking; How much can a normal oilburner pump " lift"? in feet? I would hope that a 2 ft lift would not be too difficult, but I would like it confirmed if possible. If a lift of 2 ft is no problem then I can let the tank level get down a bit lower without worrying about any oil 'starving' burner problems
A lot of single feed line tank installations have the tank located on grade level and the furnace (burner) is located perhaps 6-8 ft lower,in a Basement) thus a gravity feed no really depending on a pump. Of course a check valve would be installed no matter what difference in level.
Thanks for any info regarding this .
Edited 3/5/2005 5:17 pm ET by Hube
You are fine until you actually do run out. Then you will have to bleed the line again to get fuel flow
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Piffin, thanks for your reply. Irealize if the oil level is below the intake that after adding oil Iwill have to "purge" the line, etc. this is what I'm trying to avoid.
Are you saying then that the tank's oil could get down to approx 3 or 4 inches or so above the tank bottom without any problem.? If so, this would mean that the pump is 'lifting' because the oil level is then below the burner level when less than a third full.
I guess the bottom line of what I'm really trying to find out is;
How many feet can a single line oil burner's pump "lift" without having to go to a double (supply+ return) line.
Beckett burner, Danfoss pump, 3/8" supply line.
I have done a search on the net for some info on these pump 'lift' specs, but with no luck.
Let me put it more clearly.My burner sits fours inches higher than yours in relation to the tank and will keep drawing oil until it is gone.
I caretake another house where it is similar to yours and it will draw oil and burn it until it goes dry.
I have done a lot of remo work on a house wherethe tanks are at the same level relative to the burner as yours, but because of the terrain, the supply line loops up three feet and back down again to the burner
Even with that unique situation, the burner puimp can draw oil until the tanks go dryDoes that answer your Q?
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Piffin and Bill; thanks for the info.
and yes, it seems to make sense that the pump should take all the oil without any problem..
I was just looking for a more precise lifting limit, or a type of formula that would acertain a lift limit at a specified length from the tank to the burner.
oh, well ,i'm going to let this tank get down to near empty before I order more fuel. This will verify that the pump is ok for this small lift. Thanks again
It has about 35 years since I had an oil burner and we used whale oil in it so my memory is rusty.But if I remember correctly the pump is "high pressure" to atomize the oil in the burner.Don't have any idea if the pump is centrifical or positive displacement.But for centrifical pumps the term for the paramenter is NPSH, net positive suction head.And that can be 15 to 20 ft or more. As long as the pump is primed.