there's no water in it yet, that's the temporary sealant I've used while I test the setup.

also the performance is even better than I initally thought, when I first assembled it I had alignment problems that would cause some of the impellers to jam, well after I thought I had fixed that I did that head test, it turned out that the pump at the intake end had jammed again!, so it was doing 2.5m head with only 2 pumps going!

I got all 3 pumps going and ran out of ceiling, lol, (I have 2.6m ceilings) I'll have to test it outside in the morning, it looks like it should be about 3m or so.

I havn't addressed the valves yet, but they will get looked at when I do some more in depth testing.

Wow Volenti, your results are impressive!!!

I consider your pump mods saga to be one of the "greatest invenions for the DIY". It desserves to be on a permanent place in the site for future reference.

I see the title for your bidirectional pump mod shining on the main procooling page:

"UNCOVERING YOUR HIDDEN PUMP POWER" by Volenti :D :D

Well I must say I'm pretty happy:D

here's the head test setup showing the max head (all 3 pumps going)

http://users.bigpond.net.au/volenti/3pump_head.jpg

results;
3 pumps - 3.4m head
2 pumps - 2.3m head
1 pump - 1.2m head

in-system flow rate tests to come.

OH man thats a SWEET setup~ whats the GPH at the 3.4M head?

0

it's simply a measure of the maximum pressure the pump can achieve. It's the same with most other commercial pumps, unless they say something like "350GPH@2.5m head" then they are talking about the max head that the pump can achieve, there's no actual water flow at that point.

I wish I had the ability to do something like that. :D

I think that's perhaps a bit much. With all due respect to Volenti's work (don't get me wrong, I love much of his work, especially his direct die stuff) he's really only reworking the set-up to correct some of the design compromises that were made in the construction of the pond pumps he's using. A simpler (and likely more expensive) approach would be to use pumps that are already optimized for impellor rotation in only one direction.

It's the cost difference between them though is'nt it?. 1 Iwaki20RZT will cost me £165 in the UK, I could mod two1250 Eheims an run them parallel for under £90!. three of them would surpass the Iwaki for £135!. It's not just the headmod either, it's the triparallel mod too...

Plus no~one has done it before ;) ...

Well I know it's an exaggeration, but the point is that it reflects true overclocking spirit: not sticking with manufacturer assigned performance, but seeking the limits of any hardware. It sure could be a good candidate at Pro/Geeks.

Here in Canada it costs about the same for one MD-20-RZT (~$222) as it does for two Eheim 1250s (2 x $120). Sure, the three Eheim 1250s in series may surpass the Iwaki for maximum head rating, but only if the gain in head from the dual outlet modification was able to completely negate the flow resistance generated from the pumps being connected in series (and then some). However, the Iwaki still wins on maximum flow rate, since it's smaller than for the Eheims (2.9gpm versus 5.28gpm), which means you aren't pissing away pressure by trying for unrealistic flow rates. Add into that the increased potential for leaks, and, well...

Like I said before. I am not trying to rain on Volenti's parade. It's a great and creative project, and I am thrilled to see him succeed. However, much like overclocking, better performance can be had by spending just a tad more money in the first place. Volenti, if you're reading this, please don't think I'm picking on you too much...

I take no offence, this whole project (and my other projects) wasn't performed for cost reasons, it was an exercise in what could be done, and to further my own knowledge and understanding of how these pumps work in a practical sence.

If I could get an MD-20-RZT locally (or even on-line within australia) I wouldn't have hesitated to get one, and this mod would never had happened.

Well use a Via then :p...

Think of all the people who actualy own pumps that they can now (if they've the initiative) mod to maybe double the head of their pumps.

Tell me Skulemate what kind of pump do you have in your rig?...

This mod could also take an advantage in pump heat (total wattage) versus head, compared to buying a higher rated pump.

I currently have a Little Giant 3-MD-SC, as it was easily attainable when I built my system. It works quite well, though the flow from it is a bit too high considering its head rating, but for now it's doing the job I suppose. However, I've sourced and priced the Iwaki MD-20-RZT, and I'm planning to make the switch sometime early next year.

Numbers were on my side and still I failed :mad: ...

Nevermind! :p ...


I'd like to be able to afford the Iwaki but at £165($250+US!) it's too much, the Eheim was too much @ £45!. I'll wait until I find a way of getting the valves down pat then mod it. if I could gaurentee a good cooling increase over the 1250(modded) I'd save for one, but getting it in a case is daunting as well. I'll just have to wait and pray a cheap one comes my way...