Home heating oil pipe

You can use Copper tubing. I would get a roll of 5/8" OD (1/2" plumbing size) and use flare fittings from the bottom tank valve to the basement tank. How do you want to connected to the basement tank? You want to be carefull that you do not let the garage tank which is higher to over fill the basement tank and spill all over the basement floor.

https://www.supplyhouse.com/Mueller-Industries-58REF50-5-8-OD-x-50-Copper-Refrigeration-Tubing-Coil

Or you can use 3/8" OD copper, It's less expensive, but it will take much longer to get that oil to flow to the basement.

Like Ed said that is #1 Concern

 "You want to be carefull that you do not let the garage tank which is higher to over fill the basement tank and spill all over the basement floor."

Can you post some pictures of the setup, and the "hose", and what you're trying to accomplish by connecting the two? Because what you're doing sounds very scary, and does not exactly adhere to any code that I know of.

If you have natural gas to the house you should think about a new gas boiler or Power Burner natural gas conversion burner if you can find a qualified tech. With the looks of that I would be worried about what else is not even close to being safe, or reasonable close. I know you came here because you know that it is not right, now is the time to bring it up to a fully safe system not one that just changes out the garden hose, that is still piped wrong and a big spill hazard. it's not worth the risk.

Are the two tanks sitting at the same hight ? If they are on different levels , you can't pipe together with out creating a Hazard …….

I haven't chimed in — folks seem to have covered this pretty well — except for one things: the reason I am frankly horrified at the garden hose idea is that over time the oil can and will attack the material of which the hose is made. Now if the valve at the outside tank is always off, OK — though always is a dubious fail safe measure — but one of these days you will open that valve and the garden hose will burst. If you are there and can see the length of it, OK, it will be a minor spill, but still not what you want.

I'd use copper pipe myself, and I'd get a long enough coil as to reach the full length with no joints except, obviously, at the ends. Fewer points to fail.

I'd also see if I could find a float controlled shut off for the system, so that you CAN'T overfill the basement tank, even if someone isn't paying attention.

I still don't like the setup, but…

You are quitee right — in most areas propane is anywhere from more expensive, per BTU, or wildly more expensive.

(I always get a slight chuckle out of "if you have natural gas" — considering that the vast majority of the land area of the US does not have natural gas, nor any likelihood of getting it, it seems an oddly urban oriented question. But maybe that's because I live on a farm…)

The best pipe to use is copper with a plastic cover. Even Amazon has it:

Amazon.com: Mueller Streamline DG06050 Coated Copper TUBING, Orange, 3/8 in. OD X 50 FT : Industrial & Scientific

The tank at the house should have its own fill and vent, with a separate delivery directly to that tank, with no piping at all between the two tanks.

This system has a high probability of failing with a high cost. These are the situations in life that you want to rethink ASAP.

A garden hose can fail at any time. It is not tested for fuel oil or its additives, so I would expect accelerated deterioration.

Repiping might be lower risk but it doesn't take much to damage. Falling tree, construction, fence removal, etc. The elements will take their toll over time. There should be regulations for outdoor transfer of fuel oil that might provide some guidance but this is such a risky proposition...

A glimpse into the oil spill business should be a wake up call. These are interesting videos in any case:

https://www.youtube.com/@TankMastersEnvironmental

In order to understand how most people deal with fuel oil tank deliveries, Many who ar at work when this happens, you should read this article:

https://www.fuelsnap.com/blog/how-to-fill-a-home-heating-oil-tank/

To understand why professionals and others on this site are somewhat horrified with your setup, you need to understand that many of us deal with many customers over the years and have had experience where oil has found its way from the tank to the ground around a home. when that happens the cause could be an irregular storage tank situation that the average homeowner may not understand. But no understanding what can happen may cost you thousands of dollars in remediation costs. We are just trying to make your life easier.

Now I know that you are smart enough to make sure this never happens, but… What if you are on vacation or in the hospital and a friend is watching the place for you and there is no heat in the house. The helpful friend assumes that you have no heat because the basement tank is empty. The helpful friend has watched you do this before ans puts the feed line from the garage tank into the basement fill pipe. then he opens the garage tank valve to fill the basement tank. Just about the time when the basement tank is almost full, the phone rings and your helpful friend gets distracted and there is still 75 gallons of fuel in the garage tank but no more room in the basement tank. You come home from the hospital or vacation to a back yard with 75 gallons of fuel oil in the ground.

And I have seen this happen more than once. cost the homeowner big $$$$ for that cleanup.

I apparently did a bad job of communicating that it's not strange to ask someone if they have natural gas given that so many people do come to these forums with natural gas. No disrespect intended!

Heck, in the township where I live in southern New Jersey, fuel oil is the oddity. There are no oil dealers in this town of 90,000 and virtually everyone heats with natural gas. The town was developed post 1960 so that is likely a big factor.

Just don't get distracted as the fuel is transferring.

I used to operate a fuel oil delivery service from a gas station that had a 10,000 underground storage tank for the Diesel Fuel pump. We had a 40 yer old gasoline powered pump with a 2" inlet hose that that I would drop into the underground tank fill pipe. There was a 3" discharge hose that I would put into the top of my oil truck. I was filling the truck one day and was called away for a second, that turned into 10 minutes. What a mess!

Not an ideal setup but is was inexpensive… until it wasn't

@ChrisJ, you are just not looking hard enough!

@ChrisJ, AGAIN… looking on the wrong sidewalk

Sorry for hijacking your serious discussion about the proper oil line @ThreeMile

But that coated fuel line comes in 100 ft coils if you are interested. Most common size is 3/8" OD so you might want to add a pump to speed up the transfer.

Look up flaring on youtube, you'll figure it out.

Some of the reasonably priced tools on Amazon will work more than good enough for what you're after. Just make sure you do some practice flares first and try to leave some extra material when you're doing the real ones in case you mess up.

The #1 mistake everyone makes, including pros is forgetting to put the nut on the tube before doing the flare. Then you get to cut it off and do it again.