D5 pump issue?

[Bartacus]

Hey guys, pump question for ya'll. I have 2 D5 varios in a Bitspower dual D5 top, both pumps running at full speed. Since I broke the little speed dial on one of the pumps, I rigged them up so each one has it's own kill switch. That way, I could run them one at a time, and see if there were any flow rate differences between them (flow meter is a Koolance INS-FM18D digital one). Over the past 2 weeks or so, I'm been testing them by running only one pump at a time for a few days, then the other for a few days. I noticed that one of the pumps makes the flow rate fluctuate between 1.7LPM and 2LPM, where the other pump is a consistent 1.7LPM with no fluctuations. If I run both pumps together I get 2.9LPM, but it bounces up to 3.1LPM because of the fluctuating pump.

Should I be worried?

[bungwirez]

you may get a lower flow rate from the one pump that is restricted by pumping through its neighbor?

IDK... but dual pumps man.. I'll never do it again.

[Bartacus]

I was thinking about that too, if it could matter which half of the dual top the pump was in.

EDIT: further to that point, the reservoir is also sitting directly above one of the pumps. Another factor.

[Akira749]

I was thinking about that too, if it could matter which half of the dual top the pump was in.

EDIT: further to that point, the reservoir is also sitting directly above one of the pumps. Another factor.

I also think that where the pump is placed might be responsible for that change in flow rate.

[Bartacus]

Not sure if it matters, but the fluctuating pump is the right side one, not the one under the res:

[DazMode]

Could be still bubble inside top so flow rate us inconsistent. I have solid 3lpm no fluctuations. One pump 1.5lpm

[DazMode]

Another possibility is bad wiring. Re crimp molex connector.

[Bartacus]

Another possibility is bad wiring. Re crimp molex connector.

A ha, this sounds like a more likely culprit. Every molex connector I have seems to be messed up in some way (crooked pins, pins popping out during connection, etc). Hate those damn connectors!! As soon as my latest Daz order lands and I can tear down the loop, I'll have a close look at those.

[nass]

sounds like the 2 are fighting each other with a rate lower than both on there own once 2 are running, top, fittings and air could all contribute to the loss...

[Bartacus]

I would have thought that too except for the fact that one pump causes the flow to fluctuate on it's own. It doesn't happen all the time though, so there could be a lot of other factors. This loop is a fairly complex mess.

[nass]

my reasoning is the loss you get with the 2 running compared to each one on its own 1.7 min x 2 = 3.4 you are getting 2.9 with both pumps on idea. Wouldn't really worry about it, is too many factors that can contribute into the loss's. Both are running results = your loop, and parts used.

[Bartacus]

Ahh, gotcha. I'm not sure how the math works with 2 pumps in series, but I don't think you're supposed to get double the flow. No idea why though, since I have no understanding of hydrodynamics. So many factors with this stuff! I'm considering pulling one of my rads from the loop since it's massive overkill and just makes things more complicated. When that happens, it will be interesting to see if that flow rate changes at all. Also have an anti-cyclone fitting coming from Daz, but I have no idea if the minor cycloning I see in my res impacts flow rate.

[nass]

I use fan controllers on my pumps for example the living room htpc dcc is a cyclone when run on its own till the motherboard fan controller kicks in idea then is silent and normal. More rads means more fans and lower speeds and less noise and same cooling potential, if was me use more rads= more surface area,for cooling, imho. Pump speed in these loops dose nothing for u as far as cooling been allot of debates over this over the years... More surface area is your best bet with more fans working one pump on low believe would give u the same temps.

[bungwirez]

very true Nass... same argument for single pump system eh?

[nass]

ya just leaving parts sitting in box's or bags bothers me, have the room so will figure out how to use them, usually means buying more stuff though lol.