TEC Chiller Project

[zipdogso]

But being a bit of a technophile who likes building stuff, I’ve decided to build a TEC-based chiller
So here’s the plan:
2 QMax 437 (allegedly, apparently more like 400- thanks for all your advice Uncle Jimbo ) TECs from FrozenCPU running in parallel, undervolted to 12 volts (so CoP > 1)
3-15 Volt 25 Amp continuous switched mode power supply (£59 reduced from £99- bargain)
TEC power controlled via the PWM booster described by Ultrasonic 2 (thanks for your help on this too) hooked up to a T-Balancer BigNG (with the capacitor on that output channel removed)
Custom TEC waterblocks
Cold side loop pumped using my existing Laing 3.1 with XSPC Res Top (insulated)
Chiller cooling CPU only, graphics cards and motherboard waterblocks will be in the separate hotside loop pumped by another Laing 3.1 with XSPC single Bayres and cooled by the Feser 480
T-Balancer will control the hotside loop temperature via the rad fans
First off the waterblocks- since I work in a University I fortunately have access to excellent machine shop facilities which the guys are happy to let me use. Block bases are copper 80mm x 140mm x 12mm thick, with 5mm wide x 10mm deep channels, flycut on the bottom and then lapped:

I did these by hand (took a while...) since I have no idea how to program the CNC mills
The tops are 8mm Delrin, sealed onto the blocks with 0.5mm thick butyl rubber gaskets which cover the whole surface and so seal the tops of the water channels from one another.
The TECs are clamped between the 2 blocks using Arctic Ceramique TIM and 6 M4 bolts tightened to 15 in lbs each which gives a clamping pressure of 250 psi- mind you I couldn’t get hold of a suitable torque wrench so used the trusty long Allen key and spring gauge method. Here is the finished article- not insulated as yet:

Looks good...you've done your research.
It's a moot point, so long as you don't crack your pelts but 15lbs per screw is well over 250psi.

T = (C x D x F x in²) / (# of screws)

T lbs per screw
C is torque coef. 0.2 = stainless steel
D nom. size M4 = 0.112
F force we will use 300psi
in² 2x 62mm x 62mm = 11.52

(0.2 x 0.112 x 300 x 11.52) / 6 = 12.9 lbs per screw for 300psi

Torque wrenches are often way over ...more often than not starting at 20inch lbs you needed a torque screwdriver - much smaller torques.

Pleased to see you got yourself a nice variable PSU those meanwell things are not as useful as they could be.