Electric Pump Control

[gflower1]

I see a lot of posts on different threads discussing the use of needle, gate, ball, cock valves etc to control flow of water to with RC or PCs.

I'm wondering about using a potentiometer to control the flow.

What I don't know yet, is how (and it may vary between pumps) controlling the input power would affect pimp speed.

Would it:
a) turn my pump into a variable speed pump
b) only turn the pump on full speed when I dial in enough power
OR
c) create a fantastic explosion of sparks and smoke while effectively burning out said pump and parts

Any input welcome. Thanks!


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[rad14701]

You would need a power controller, much the same as what is used for internal electric heating elements for heating boilers, not simply a potentiometer... Some pumps can run at variable speed while others can't... Utilizing a bypass valve is a far simpler, cheaper, and reliable solution...

[gflower1]

Ah, I knew there was an answer! I was just looking at some homebrew controllers and wondered, if there's already a switch...? Lol
So it would need another SSR?

Anyway to tell from packaging which pumps can and can't?




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[still_stirrin]

Any way to tell from packaging which pumps can and can't?

Cheap pumps usually cannot be speed regulated by SSR simply because they can over heat. I would hesitate to regulate a $20 pond pump with a SSR circuit. But if you have a 1/2 hp recirculation pump (much more $$), then it likely could be regulated.

I agree with Rad...the cheapest and easiest way to control water is a bypass circuit...plumbed from the outlet back to the inlet with a valve to control the flow. Its simple to build and very effective for all kinds of pumps, including the magnetic drive pumps too.
ss

[gflower1]

K.I.S.S. is the way to go here then. Definitely not going to put the time or money into that... Just wanted to explore the idea.

Thanks for the feedback guys!

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[UnSub]

My understanding is (if I remember correctly) AC is much easier to modulate than DC. But why bother? Pumps have no problem running with back pressure. A valve will result is the same outcome and doesn't potentially harm the pump as some pumps are designed to run at a specific rpm or the can stall (bad for distilling)..
Just my .02


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[gflower1]

I've got a small pond pump (110vac) to use but was considering upcycling some small bilge pumps that would require a 12vdc battery or converter.

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[still_stirrin]

So, be careful...bilge pumps are not rated for continuous duty. They will overheat and fail prematurely.

A bypass valve is NOT simply a valve on the outlet. It uses a Tee on the inlet and outlet with a valve located in the return from the oulet of the pump back to the inlet. It makes a short loop between the discharge and the suction (inlet). You can regulate the amount of water from the outlet to the inlet, keeping the pump flowing at full volume without backpressure.

A bypass circuit will not cause premature wear on your pump. And you can easily do this with any size pump, including your dimestore pond pump.
ss

[gflower1]

Like this?


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[pfshine]

Pumps have no problem running with back pressure.

Not true it can severely shorten the life of the blades. The pressure can cause the water to cavitate on the blades.

[gflower1]

Not true it can severely shorten the life of the blades. The pressure can cause the water to cavitate on the blades.

True. I thought I replied to that last night but guess it didn't post.
Try telling that to the 27 inch pumps with 70 inch impellers at my work!
It's amazing what cavitation can do to some hard platted steel pump shells


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[FreeMountainHermit]

gflower1. I use a series of Tees on the inlet hose side of my condenser as bypasses that continuously bleed back to the reservoir with a needle valve controlling the final flow adjustment at the condenser inlet.

Eazey Peezey