MCP655B shuts off around -14C

I've bought new pump to my chiller - MCP655B. Chiller is quite strong, 6.8k btu rotary, 10 plate heat exchanger, I have MCW60 and D-Tek Fuzion V1 in my loop. The problem is, that pump shuts off around -14C. I'm using coolant for car radiators, almost pure (designed up to -35C), it gets really dense in those temps, flow is really low and I'm almost sure, that pump is overheating (I had the same in MCP350, but around -7C).

Any suggestions? Mabe I should change my liquid to something else? (or add some alcohol)

You might want to move to something a bit beefier and not encased in plastic that may start to degrade or get brittle.

I would suggest an iwaki or panworld pump off ebay.

Iwaki MD-15R-NL09 will do the job? Or two of them? ;) I've some on polish auction service, they're really cheap due to operating voltage (100V instead 230V, which we have in our country). I've just need to buy proper transformer.

Buy the anti-freeze as concentrate rather than ready mixed coolant then mix it yourself.

I ran my chiller down to -25° like this with a 30% mix (overkill) and saw no issues with d5 pump

I have a similar setup on my MOAF cooling but with a central heating pump and a 20% mix. That pump is a Grundfoss Alpha (pic Here )

I've changed the liquid, now it contains:
1,0l of 95% alcohol
1,0l of water
1,0l of coolant for car radiator (rated for -35C)

It freezes in -24C, but my pump doesn't shut off anymore, what is good. I added another 0,5l of alcohol, but I haven't tested it yet. Around this temp I started getting issues with condensation on tubes (all tubes have 13mm thick insulation, but they're getting a bit wet).

Anyway I decided to change MCP 655B to two IWAKI MD-15R pumps connected in series. With proper transformer it should costs me around 80$ and it should produce much bigger flow than Switftech pump, especially with 3 block (2x MCW60 and Fuzion V1).

I'll keep you updated ;)

When trying to fight viscosity and work issues, series isn't always the best approach. When you get to it, test and compare series to parallel pumping, you might find some extra benefits.

Finally I found the best pump configuration for this chiller. Two Iwaki MD-15R pumps connected in series - that's the best choice. I can go up to -25C with three water blocks with mix, which I posted in my last post in this thread.

I've done some good scores using this equimpent in last two months:

http://hwbot.org/submission/2302430_...gt_30011_marks
http://hwbot.org/submission/2302431_...gt_89018_marks
http://hwbot.org/submission/2312776_...90_26897_marks
http://hwbot.org/submission/2310129_...gs_33984_marks
http://hwbot.org/submission/2309934_...gs_14523_marks

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