Size of supply line

Can anyone tell me the proper size of a copper oil supply line. The line is
25 ft long and comes from a tank located outside and continues inside the crawl space. The concern being that the oil in the line keeps freezing. the current copper line is 1/2in. The crawl space is heated but the outside line to the tank is exposed the elements.


Adam O’B

You are slightly colder than our area but the supply line on my rental is about 25 feet also. It is 3/8 tubing and original to the house. About 50 years old and works fine as long as you change the filter yearly. I would think that 1/2 inch would be more than suffecient. The heating oil won’t freeze, but it will thicken (waxing) quite a bit and that will strain the pump. Actually that is not true. Kerosene will freeze at -73 degrees Celsius, which works out to -99.4 degrees Fahrenheit. I would recommend an insulating tape be added to the exposed lines. There is also an anti-freeze that can be added to the oil to keep it from thickening as fast.

Most external tank supply lines are 3/8 inch and it does help to have a two-line system.

Stephen is correct – the oil is not likely to freeze…however, traces of water can enter the oil at the distributar, or while in the delivery truck, or in the home oil tank. This moisure can freeze, and it recommended in cold weather areas that an anti-freeze be added to avoid blockage in the line.

Heat tapes are also effective, to a point. If the temperature drops very low, the tapes become less effective.](

Thanks, for the fast replys. I will suggest insulating the pipe that is exposed to the elements. The major concern was the size of pipe. Thanks again.

Adam OB

Another solution would be to use mobile home blend, all mobile homes in my area that burn oil use this blend because the tanks are located outside. I believe it’s a mix of oil and kerosene but I’m not sure on the ratio.

In my area, outdoor tanks use #1 fuel oil and indoor tanks use #2 fuel oil.

#1 fuel oil is akin to kerosene.

Info on Fuel oil types:

There are additives on the market that I’ve seen that are used to prevent fuel oil from gelling under cold conditions. Some fuel suppliers add this to their product prior to delivery.

This information might help .
Sure helps to add conditioners to my diesel equipement on the jobsites.

Marcel :slight_smile: :slight_smile: