Dip tube placement???

[kuribo]

I have two 500 gallon propane tanks I am plumbing up for storage. They will be plumbed in parallel and will be used in a horizontal configuration next to each other as I didn't have the head room in my basement to stack them or stand them up....

I had 2" fittings welded on the top of the tanks for boiler supply/return and zone supply/return. I only need 1" lines in/out of the tank and will use 1" black pipe inside tapped bushings to connect to the tank. I have found that I can put a 90 elbow on the end of the dip tube (to redirect the inflows/outflows along the horizontal axes of the tanks so as to maintain stratification) and they will fit through the 2" welded on fitting.

Here's my question: how long should I make the dip tubes? I was thinking to place the boiler and zone supply tubes about 3" down from the top of the tank and the returns about 3" up from the bottom. Does that sound reasonable? Wondering what others have done....

Thanks.

 

[jebatty]

In my horizontal tank which I supply from one end and about 6" down from the top I inserted an 18" horizontal tube to direct flow across the top of the tank. The return is about 6" up from the bottom, no horizontal tube, and on the same end as the supply. At my flow rate of about 14 gpm stratification is very good. Based on my temp sensors the temp in the bottom 6" clearly warms much more slowly than the water at the 6" level and above. Therefore, I think placing the return as close to the bottom of the tank that you reasonably can would be beneficial. In a cylindrical tank, there really is not very much water in the bottom few inches of the tank, so I don't think a person needs to go overboard in trying to reach the bottom. There may be some benefit to staying off the bottom, as the bottom may collect some debris which best should remain there.