Pump Box - Dual 12V pumps with PWMs

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Weezy

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I'm knee deep in the process of building a single tier, countertop, small batch Brutus 2.0 rig. An important part of the rig are two pumps, necessary for cross recirculation between the MT and HLT. So I built this pump box using a 6"x6" conduit box, and two ebay 12V solar style pumps. Each pump is run by 12V PWM controller, intended for LEDs but works just fine on these pumps.

pump_box-62796.jpg


I wanted something compact, to not take up much space, and my experience with the 12V pumps has been good so far.

The pumps are mounted by sandwiching the inlet across the back side of the box, between a 1/2" PEX-to-1/2" NPT compression fitting and a 1/2" electrical conduit nut (these cheap things are like $0.84 for a 4 pack and function good as a lock nut for this application). The holes are 7/8".



The outlet side of the pumps come out through the top (lid) of the box, and are also connected by the 1/2" PEX fittings. They are not sandwiched to the lid though. No need.

The 1/2" PEX connects perfectly to 3/8" silicone tubing, which is more than enough for these pumps and small batch brewing.

The PWMs mount through the front of the box. The stem of the potentiometer isn't long enough to directly mount in the typical through-hole-mount fashion with the small nut on stem. So I simply put 4 dabs of silicone on the face of the PWM and stuck them to the inside of the box.



The backside view shows the inlets on the back with 90 degree fittings and the outlets at the top with straight fittings.



The aluminum plate is merely hiding my screw up. I drilled one of the top holes in the wrong position....oops. A free piece of aluminum laying around is cheaper than a new project box.


Parts list:

1. Pumps are 12V, 1A, 600L/h, high temp, ebay specials, drop shipped from China for $17/ea
2. PWM controllers $3.25/ea
3. Home Despot Electrical 6"x6" conduit box $12
4. Home Despot Electrical 1/2" conduit nuts $1
5. Home Despot 1/2"PEX-to-1/2"NPT fittings $2.50/ea for straight and $3.50/ea for 90 degree
6. The fancy knobs and aluminum I had laying around
7. The power supply is a 12V 2A supply I had laying around as well.
 
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Nice looking pump box! So you wired the PS to both pumps? Isn't there a power loss or are you not running both at the same time?
 
I run pretty much exactly the same setup. The LED dimmers work awsomely to control the pumps. Not even as much as any audible 'complaints' from the pumps even though the PWM frequency is in audio range. I think this combo is probably the best value for money there is on the home brewer scale. The pumps dont have an awful lot of head, and not a tremendous flow rate either, but in my book that is a plus anyway. And they are small, cheap and quiet. Kudos on the build!
 
The ones I have a frequency around 1kHz. They are based on a pretty simple (but clever) 555 timer circuit, so changing the frequency is not that difficult if you are able to solder. See this thread for details.
 
I run pretty much exactly the same setup. The LED dimmers work awsomely to control the pumps. Not even as much as any audible 'complaints' from the pumps even though the PWM frequency is in audio range. I think this combo is probably the best value for money there is on the home brewer scale. The pumps dont have an awful lot of head, and not a tremendous flow rate either, but in my book that is a plus anyway. And they are small, cheap and quiet. Kudos on the build!

Good point. You're not going to use these pumps to force clean kegs or anything like a CIP ball. But a modest flow rate is what you need during mashing, lautering, and sparging.
They're enough to whirlpool, if that floats your boat.
 
Thanks! I want to create the PWM with my Arduino and a SSR similar to what I do for heating elements. Of course, there is no real reason to do this, except for fun.

Really great build and definitely inspiring.
 
Hey Weezy

That's pretty cool. I'm looking to do something similar in terms of setup. I've got a 5 gallon system that I run off a BCS 462 control box. I've also got a 1 gallon system that I'm trying to turn into a self-contained automated countertop rig. I'm looking at the same pump that you are using. How do you like it? Is it working well? I'm a bit concerned about the durability and safety of it.
 
Hi
I'm from NZ and am trying to find pumps a little more local but can find anyone that can answer if the pumps they have listed are compatible with PWM - I've take a look at the link above and can find it in the spec, how were you able to confirm they would would with PWM as the first pumps I bought only run when power is at 100%

Thanks
 
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