Opinion on a pump needed

I'd like your opinion on a pump that I have selected for a watercooling setup I am planning on creating sometime in the future. (note I already own the pump)

I looked around using the search function to see if this pump had ever been mentioned before, but didn't see anything.

The pump is a Hagen Powerhead 802 submersible pump
400 GPH at max flow rate, the flow can be restricted
6.7 GPM
4' of in line pressure
1/2" ID compatible



I was planning on building a Resivor out of some thick acrylic or possibly a rubbermaid container with the pump epoxyed in place. I know having a submersible pump will generate some heat.

I was looking at a graph just a little bit ago, and noticed that waterblock efficiency seemed to drop as flow rate increased. Most pumps and block run around 1.25-2.9 GPM. So this pump would be extremely overkill.

What are your thoughts about it? I posted this idea a couple of times at overclock.net, but there are more people here to respond ideas.

I don't think this would be a very good pump for water cooling. I'm not an expert on pumps, but my reasoning is this: Most water cooling setups are pretty restrictive and if you go with any of the current higher end blocks they can become very restrictive. That pump only has 4' of head with NO restriction. As soon as you put a block or two on it flow will be cut to almost nothing because the pump can't produce enough pressure to get through the blocks. Your 6.7 GPM will be less than 1 GPM almost immediately.

Take a look at the flow rates and head measurements of pumps that are generally recommended or even talked about. While the overall flow may not be that high, the amount of presure the pump generates makes sure that flow can occur in a restricted loop. For example, the Liang D4 is rated at 317 GPH at 10' of head, the AquaExtreme 50z is rated at 185 GPH at 10.5' of head, the Iwaki MD20RZ is rated at 174 GPH at 22.6' of head.

Cathar has a good (great?) post over at ProCooling you should take a look at. Here's the link: http://forums.procooling.com/vbb/showthread.php?t=10825&highlight=pump+review

yeah, you definitely need a pump with a higher pressure head

the thing about pumps is that they may pump more water, but only to a certain point - yours stops at 4ft, others pump up to 10-20 feet, and in a restrictive water cooling system, the amount of pressure head that your pump can put out is very important, because if you exceed the rated head of the pump, you usually have little to no flow through your system


another thing you have to figure into the equation is how much heat the pump will be dumping into your loop, as most mag-drive pumps are cooled by the liquid thats being pumped through it - so the more heat your pump adds to the loop, the more heat your radiator will have to handle, which usually means you sacrivice your ears for more fan power for the radiator, or your loops performance due to raised water temperatures

The Hagan pumps are great for aquariums, where flow is needed, but you don't generally want to blast your tank with a fire hose (AKA pressure, those poor fishies).

As mentioned above, restrictive loops will degrade your pumps performance, especially one that does not supply allot of pressure.

Hydor pumps are similar to the Hagan pumps, and basically use the same internal design. an Omni directional impeller, with a centered outlet. This allows the pump to generate lots of flow, and also allows for a simpler pump design as the impeller can spin in either direction and still provide flow. However, the centered outlet sacrfices pressure for added flow (generally speaking)

Often you will hear people asking why their Hydor pump is "ratteling". This is because they have the pump in a loop which is borderline too restrictive. What happens is the impeller begins to ocilate as it tries to maintain the flow rate with the increased back pressure. I would surmise the same would be true for the Hagan pumps, as they have the same internal design.

There are some loop designs that can help get around this, and mixed with the right componnents high flow/low pressure pumps can be great performers. Generally speaking though you are better off with a pump with a higher head.

If you plan on using any of the newer water bloocks, which all pretty much feature a spray nozzle design of some kind. You will want more pressure. Soemthing liek a Maze4 may benefit more from a higher flow pump.

I actually read about one setup a guy made for watercooling and he did use this pump. I'll just have to look around for a high flow / low pressure block.

I would suggest the Swiftech 6002, or you could go with a TDX or RBX from DD, and use the #2 plate ( I think thats the wide one, or make you own wide slotted plate)

FYI, you'll know your loop is is to restrictive if you hear the pump start to "rattle".