Pro/Forums - View Single Post - Y pressure drop / Rads parallel or series

Long Haired Git · 10-26-2005, 11:08 PM

Cathar tested dual BA radiators and found that serial was better in his rig on the day he did the testing. Its the case that parallel results in half the flow rate in each rad which does reduce performance, but it also reduces the overall restriction and thus increases overall flow rate to a small degree, but then you also have to factor in the impedence of the Y fittings.

The "Y"'s add restriction, most notably for 3/8" tubing and barb rigs. My modelling (cringe, I am crap at it) shows 1/2" barbs 30mm long with 8.46mm ID creates approx 20cm of head at 5m. 3/8" with 7.1mm ID Y is 40cm of head. I've assumed the Y "convergance" has the same head characteristics. Note also that my modelling results in barb conversion effects about 20% higher than noted in BillA's testing of HE rads with different barbs.

Time for approximator!
Swiftech MCP655 @ 5, Swiftech Storm block over 70W. In serial, I have 2m of tubing, whilst in parallel I have 1.2m outside of the two Y peices, and then 10cm runs from the arms of each Y to the radiators.
Each MCR220QP radiator has a fan at 7v as most people run rads like this these days.

Serial: 6.4 LPM, pump adding 16.2W, water temp at exit of pump is 2.2°C, CPU delta-T is 11.5°, radiator C/W is 0.0492
Parallel: 6.05 LPM, pump adding 16.0W, water temp at exit of pump is 2.3°C, CPU delta-T is 11.6°, radiator C/W is 0.0529

In parallel, I approximate the head of each Y connector at 29cm of H20.

Anyone want to do a PQ graph of a common brass 1/2" Y for me? Even a single flow rate value would be SOMETHING!?!?!

Assuming my approximator is correct, it looks basically the same either way you do it. So, plumb it the way that's most convenient, which is typically in serial.

10-26-2005, 11:08 PM	#7
Long Haired Git Cooling Savant Join Date: Jan 2003 Location: Sydney, Oz Posts: 336	Cathar tested dual BA radiators and found that serial was better in his rig on the day he did the testing. Its the case that parallel results in half the flow rate in each rad which does reduce performance, but it also reduces the overall restriction and thus increases overall flow rate to a small degree, but then you also have to factor in the impedence of the Y fittings. The "Y"'s add restriction, most notably for 3/8" tubing and barb rigs. My modelling (cringe, I am crap at it) shows 1/2" barbs 30mm long with 8.46mm ID creates approx 20cm of head at 5m. 3/8" with 7.1mm ID Y is 40cm of head. I've assumed the Y "convergance" has the same head characteristics. Note also that my modelling results in barb conversion effects about 20% higher than noted in BillA's testing of HE rads with different barbs. Time for approximator! Swiftech MCP655 @ 5, Swiftech Storm block over 70W. In serial, I have 2m of tubing, whilst in parallel I have 1.2m outside of the two Y peices, and then 10cm runs from the arms of each Y to the radiators. Each MCR220QP radiator has a fan at 7v as most people run rads like this these days. Serial: 6.4 LPM, pump adding 16.2W, water temp at exit of pump is 2.2°C, CPU delta-T is 11.5°, radiator C/W is 0.0492 Parallel: 6.05 LPM, pump adding 16.0W, water temp at exit of pump is 2.3°C, CPU delta-T is 11.6°, radiator C/W is 0.0529 In parallel, I approximate the head of each Y connector at 29cm of H20. Anyone want to do a PQ graph of a common brass 1/2" Y for me? Even a single flow rate value would be SOMETHING!?!?! Assuming my approximator is correct, it looks basically the same either way you do it. So, plumb it the way that's most convenient, which is typically in serial. __________________ Long Haired Git "Securing an environment of Windows platforms from abuse - external or internal - is akin to trying to install sprinklers in a fireworks factory where smoking on the job is permitted." (Prof. Gene Spafford) My Rig, in all its glory, can be seen best here AMD XP1600 @ 1530 Mhz \| Soyo Dragon + \| 256 Mb PC2700 DDRAM \| 2 x 40 Gb 7200rpm in Raid-0 \| Maze 2, eheim 1250, dual heater cores! \| Full specifications (PCDB)