The impact of tubing sizes

[Cathar]

Okay I know this is a little off topic, but here it goes.
Petra calculated that the DDC-2 is about 15% efficient. The other 85% has no place to go except to be turned into heat. Common sense says that part of that heat is going into the air, the PCB, the plastic housing, and eventually...into the air from those. Another part is going into the water. Here it doesn't matter that much because its only a few watts at most. And I'm sure plenty of people have reported that their pump's cases get a little warm during operation, meaning a good deal of the heat is NOT going into the water...

Yeah, I use 16% efficiencies in my calculations when mapping from hydraulic power (restriction x flow) to estimated required pump power (power draw). I then multiply that value by 0.9 to arrive at the pump heat dump directly into the water. This is all in the estimation stage.

A DDC2 is 18-20W. At a 90% water heat dump, 2W is going into the bits not touched by water. Hook up a common DC electrical resistor to a DC power supply, and feed 2W of power through it. Wait 1 minute and touch it, and let me know if it doesn't dang near burn your finger off. That's the sort of heat that you're feeling from the bottom of a DDC. Blow some air over it and it'll feel cool all the time. Most pumps sit on their bottoms with no air-flow. Give anything small 2W of heat load and sit it where it gets no air-flow, and it WILL get quite warm.

Yer typical high-performance GPU ram chip generates around 2W of heat when under load. Touch one without a heatsink on it after its been working away for a while and you'll just about scorch your skin.

Remember, temperature != heat.