I now test as follows:
- Turn on pump and fans on radiator; adjust flow rate to 0.5GPM
- Allow to run for ~15 minutes and reach steady state
- Write down offset between wb in and out probe.
- Fire up test PC and run tests with 60 minute equil time between points. Start out at 0.5 and increase to a final "max flow" point
- Turn off PC and wait 15 minutes
- Record final offsets
The last bit isn't strictly needed; every time I have tested in the last few months the 2 probes I currently used have had a 0.02C offset (outlet higher) at 0.5 and max flow. But I figured this was the best method to spot something that might go wrong in the future as it happens.
I see some slight variation in dT wb at really low flow rates from block to block. I think it's more to do with the fact that some wbs are less amenable to insulating the outlet barb (3 barb wbs SUCK for this). At 0.75GPM and above the W calculated from dT(water) is pretty much constant for all wbs until you get to 2.5GPM and above where I hit the limits of 0.01C resolution in calculating W
//edit: If I can finish my employment package today then I'll get back in the computer room tonight. Maybe after I finish running incoherent's wb I can play with some of this stuff in earnest.