1.25" diamater VM column possible?

[subvert]

After scrapping plans to build the John Stone design in favor of a VM, I have some questions.

I built my original column from 1.25" x 3' (31mm x 1m) copper as per the Stone design, and this is reduced to 3/4" to fit my 10 gallon boiler (water heater converted to 750 watts).

Is it possible to craft a working VM still out of this size column or shall I scrap that and just go with 2" like the majority of the VM designs seen on the forum?

If so, would a 2" column even work if reduced to 3/4"?

Thanks in advance for the insight!

Candidly, subvert

[Hawke]

Either would work. The 2" would have a better takeoff rate. The choke point at the bottom of the column will slow you down a bit, but not as much as toward the top.

[rad14701]

As Hawke mentioned, both will work, but here are some figures... By linear inch of column 1.25" provides 1.23 cubic inches of volume while 2" provides 3.1416 cubic inches of volume... That's 150% more volume when using 2 inch... If 1.25" is all you can get then use it, but if you can get 2" you'll get better overall performance...

Edited: previous volume calculations were based on diameter rather than radius, falsely making volumes higher than actual...

[HookLine]

1.25" will work, but its output rate will be very low and you will quickly get the screaming heebie-jeebies with it. 2" is about the size it starts becoming practical.

[subvert]

Thanks guys, I'm convinced--2" it is. Perhaps I can use the newly-scrapped 1.25 pipe for the liebig condenser jacket.