Mixing pump types?

[RogueTadhg]

Has anyone ever mixed a DDC pump and a D5 in the same loop? One for better pressure and one for better flow rate?

 

[Dullard]

I dropped a link to Martin's Liquid Lab test on dual pumps in your Dual Pumps thread. It has the info in it, including running two different pumps - but I don't think any of his testing concluded that two different pumps could perform different functions in the same loop.

 

[Dreamerbydesign]

In a closed loop two different pumps would be a disaster.

 

[Dullard]

In a closed loop two different pumps would be a disaster.

The test in series performs very well. It is as simple as adding the two pump curves in the Y or pressure direction. The little bit of tubing between the two pumps is not a measurable restriction and the curve results are very much as expected morphing the two pump curves into one stacked curve. While this does double the pressure of two like pumps, it should be noted that it does not double your flow rate. Because the restriction pressure drop curves are not linear, you generally net around 30% more flow rate from running two pumps in series. This would be the recommended method of running multiple pumps in one loop and it does NOT have to be the same pump. A modified DDC-1 and PMP-450(D5 Vario) work together very happily together.

From

https://martinsliquidlab.wordpress.com/2011/04/26/pump-setup-series-vs-parallel/2/

 

[Tsumi]

It won't add like you think it would. If you put them in series, at low restriction you will get the max flow rate of the D5, while the maximum head pressure is the D5 + DDC. In a low restriction loop, this can be dangerous as the DDC can easily overheat. A high restriction loop would not have this problem, but in many cases, a dual pump head of the same two pumps is easier to place and often more aesthetically pleasing than tubing between two separated pumps.