[EMC2]

1) would 1/2" tubing make any real difference here?

In flow rate, a definite yes. In system performance - depends on the block and partially on the total length of tubing (which affects net gain from the increased tube size).

2) would 1/2" tubing make any reasonable difference?

Same answers as for the first.

The head would be (I believe) the sum of all the individual resistances.

Correct Key word on all. That includes bends, fittings, etc..

DG - to understand why I gave the answers I did - a given size inner diameter - be it tubing, a fitting, or a bend, has a "resistance" that is based upon both length and diameter (and the velocity of the water and the radius of any bends). In the case of the fittings on the block, while they might only be 3/8" unbored out, they are also quite short in length. The tubing on the other hand has significant length, and actually more restriction per unit length than the fitting does for the same diameter (due to the tube's inner surface compared to the fitting - unless the inside of the fitting is rough - but then if you bore out the fitting, it can be very smooth, lol).

Regarding your last question about the weight of the water - for the lengths of tubing in a puter system - you would benefit more from the reduced tube restrictions than you would loose from any issues in that regard.


I think the real questions you should ask yourself are (let's really complicate the issue)-

Will the block you have benefit from increased flow enough to warrant the increased cost given your intended use?

If the answer to the first is no, then will the benefit be enough to allow you to go to a smaller pump (less $, less heat, less electricity) than you would otherwise use?

Will the reduced flow restriction provide you other benefits that offset the cost of the larger tubing - be those benefits reduced wear on the pump, reduced maintenance, or possibly other things nobody has brought up yet.

Other than the cost of the tubing itself, are there any negative affects of the larger tubing that make it not worthwhile to use? (kind of a why not since you know the flow will increase).

If the plusses and minuses are pretty balanced - then what about future use of the tubing on your next system (i.e. pay for 3/8 now and need/want 1/2 later)