2 Rads Question?

I have Swiftech Apex Ultra setup with one 120x240 rad. The system is working fine but I was thinkig to add on a second rad of the same size as the first.

Does any one have a setup like this before? Will it worth the money to have 2 rads or it won't make any different? How much does it help in the performance? My pump is MCP655 and I think it's capable with 2 rads?

Any advise?

yes two rads will be great. many people do it. it will help reduce temps but the second rad wont be reducing temps anywhere as much as the first rad. diminishing returns with each rad you add.

the pump will handle it no problem unless you increase the headeight which will slow down a pump, even stop flow if you go tall enough. headheight is the distance from the lowest point in the wc to the highest point. 50cm or less is a nice headheight.

Unless you use the rads in parallel, of course! Use a splitter before and after, and bam... Twice as much rad surface area AND twice as much flowrate through them. I don't see why anyone would put them one after another??

the surface area is the same, there is still two rads of the same size. the flowrate halves when you use a splitter, not double. two rads in series will not affect flowrate as the second rad is just as restrictive as the first rad. the waterblock is the tightest restricition in the system anyway. in parrallel both rads will be at the same temps only if the splitter manages to split the water flow exactly in half, otherwise one rad will be hotter than the other. for this to happen both rad circuits need to have exactly the same resistance; internals, piping, the splitter, everything. in series the first rad will definetly be hotter than the second. i think the temp of the water should be the same after it has gone through both rads, series or parrallel.

http://www.ocforums.com/showthread.php?t=419042
http://www.ocforums.com/showthread.php?t=419064
http://www.ocforums.com/showthread.php?t=236190

Seems to be really hard to find any quantitative data on this subject, it's mostly just peoples opinions.

Seems most google results are about people putting blocks in parallel, not radiators.

Using a splitter to push the water through 2 radiators would be ideal for increasing cooling capacity in high volume/pressure systems, however, I doubt the 655 has enough head pressure to maintain enough flow. And besides, in these types of small volume systems, parallel cooling wouldn't introduce much of a different temperature change from 1 radiator to 2 in parallel. If it were a system of either higher volume, or higher pressure, the parallel system would indeed work. You just need a pump to maintain flow.

Thats why I got some high GPH pumps 750 and 1800 for my chiller... Cause it goes from 1/2 inch tubing to a 4 inch Pipe Heat Exchanger. A Swiffy would definately cave in to that. hehehe

But your system won't benefit from parallel

Thank you for the all the helpful info guys!
It's a tough decision to choose which setup, series or parallel?

I was thinking to use gravity to increase the water flow by put one rad on top the case, second one on the back of the case. All the water blocks, pump and reservoir are below the rads, the highest point of the rad no more than 18" (50cm). This is a midtower case.

Will this help with either way (series & paralel ) setup? What do you think?

gravity wont help you it will work against you if you are increasing the headheight. it will slow down flowrate. go high enough and gravity will be stronger than the pump and stop flow. your pump should have headheight specs. if you put a rad up high then yes gravity helps on the way down, but it is working against the pump when the water is going up!

if you are willing to put rads on top of case, mount them horizontally, with fans underneath blowing up and 1 inch between case & fans. this way gravity works with the fans, not against them = better cooling. heat rises naturally. mount the pump & res no lower than the lowest point in the wc system, this way you minimise headheight & maximise flowrate. the lowest point should be the chipset or gpu water blocks.

water blocks in parrallel, as this increases flow. rads however can be in series or parrallel, same either way. series has small advantage of simpler plumbing.