fuel line specs

MELOC · #1 12/13/05, 08:46 AM

i have a gravity fed oil heating system. the fuel line is the standard 3/8 copper tubing i think. i draw of of the bottom of the tank, the theory being that i will not accumulate sediment in the tank if i flush it out and change filters often.

the problem is with flow and for several reasons. the copper tubing has a tendancy to kink. it is not closed off but restricted at one or two places one being right at the tank shutoff valve. another problem is my lack of a straight run. my line has several turns (not kinked thankfully) and i suspect it may cause great friction. i did that to keep from tearing apart a stone foundation wall to run the fuel line. (masonry bits do not drill through quartzite very well, i tried a joint but hit stones in the middle).

i have had to fiddle with this thing far too often and when it gets cold the oil gels like oil does and it may stop the flow. my question is first off is why is it so common to use 3/8 inch line when oil gels? how big can i go? i thought of running sectional pipe but liked the idea of tubing (copper with no rust and no leaky joints). my furnace is supposed to be able to draw fuel with a minimal head and will not even though the tank is higher. it should be able to pull fuel ten feet high. i suppose if oil will not run down a tube then one cannot expect a pump to do much better.

i know i can insulate the exposed portion of the fuel line that comes from the tank. i still suspect i will have flow issues. i need to go bigger i think. i will scrape the current three year old tubing and save it for a garage upgrade. i am leary of iron pipe because of the offseason and the potential for rust from moisture sitting in the line. i am going to do whatever it takes to get a "straight run" through the stone wall. the tank and line where new two or three seasons ago.

any suggestions?

TnAndy · #2 12/13/05, 09:04 AM

Never had oil heat, but it seems going to a 1/2" line would probably help. Use refrigeration grade copper.....that will bend eaiser than type M or L roll copper.

Insulating the line might help, but I'd think unless you insulated the tank, valve and filter as well, you might be wasting your time.

Consider building a leanto shed over the tank and heat with a light bulb ?

Or going to a lighter weight oil ?......like you're using #2, mix 50/50 with #1 ? Dunno if you can do that.....but surely the problem is solvable, since lots of folks in the Northeast use oil.

agmantoo · #3 12/13/05, 11:00 AM

The volume of oil consumed per hour is not great! Even a mildly kinked line should feed. On the other hand a clogged line or a filter with water accumulated in it will cause problems. I would never take the fuel from the lowest point as that is where rust and trash will buildup. Tilt the tank where sediment will not be over the outlet and clean the filter housing of any water/condensation and try what you have. Disconntect the 3/8" line at the flow and monitor the flow. There is probably trash on the tank side of the valve. The freezing difference between a 3/8" and a 1/2" line are inconsequential IMO.

MELOC · #4 12/13/05, 11:35 AM

i run the tank dry every year and flush it out before refilling. i have seen too many 275 gallon tanks filled with 75 gallons of sludge. having the outlet on the bottom helps the drainage.

i think the kink in the line at the tank valve is killing me. i replaced the filter this morning and i still get limited flow. i get limited flow even with no filter when i am checking the line. i doubt it is sludge etc. but that is always possible. i added a bottle of "conditioner" that was aweful thick. i think i should have done it before the tank was filled so it would mix but i forgot. maybe that is plugging up the line.

i suppose my real questions are how large a line can practiacally be used? is it regulated? why do many folk (myself included) use such small line to begin with when oil has a tendency to gel?

agmantoo · #5 12/13/05, 11:58 AM

Remove the valve from the bottom of the tank and stick a wire back thru the hole and expect a gush. Have a helper available to assist in reinstalling the valve if necessary.

michiganfarmer · #6 12/13/05, 12:29 PM

Quote:

Originally Posted by MELOC

i have a gravity fed oil heating system. the fuel line is the standard 3/8 copper tubing i think. i draw of of the bottom of the tank, the theory being that i will not accumulate sediment in the tank if i flush it out and change filters often.

the problem is with flow and for several reasons. the copper tubing has a tendancy to kink. it is not closed off but restricted at one or two places one being right at the tank shutoff valve. another problem is my lack of a straight run. my line has several turns (not kinked thankfully) and i suspect it may cause great friction. i did that to keep from tearing apart a stone foundation wall to run the fuel line. (masonry bits do not drill through quartzite very well, i tried a joint but hit stones in the middle).

i have had to fiddle with this thing far too often and when it gets cold the oil gels like oil does and it may stop the flow. my question is first off is why is it so common to use 3/8 inch line when oil gels? how big can i go? i thought of running sectional pipe but liked the idea of tubing (copper with no rust and no leaky joints). my furnace is supposed to be able to draw fuel with a minimal head and will not even though the tank is higher. it should be able to pull fuel ten feet high. i suppose if oil will not run down a tube then one cannot expect a pump to do much better.

i know i can insulate the exposed portion of the fuel line that comes from the tank. i still suspect i will have flow issues. i need to go bigger i think. i will scrape the current three year old tubing and save it for a garage upgrade. i am leary of iron pipe because of the offseason and the potential for rust from moisture sitting in the line. i am going to do whatever it takes to get a "straight run" through the stone wall. the tank and line where new two or three seasons ago.

any suggestions?

are you sure the oil is gelling?
We never had heating oil gell. Mabey they put anti gell additive because of the cold temps here.

3/8" is plenty big enough.
Cut the kinks out, and splice the tubing back together. use an air compressor to blow your tank valve out. As long as the tank is higher than the furnace, your filters are clean, and the tubing is free of obstructions gravity should supply plenty of fuel to the furnace. The burner pump does provide some suction too.

mink · #7 12/13/05, 02:24 PM

take the copper tubing off the other side of the filter to insure that you have full flow, this will eliminate a problem from the tank to the far side of the filter. if you have full flow disconnect it off your furnace ...drain into a can... check for difference in flow. up here in new york the outside tanks usually use kerosene or at least a 50-50 mix in cold weather. as for boring a hole threw the stone a hammer drill will do the job very easy....mink...oh and 3/8 copper is all thats used here and the temp goes to -25 for sometimes a week or so