Building a Pump Relay...

Hey peoples,

I have a MaxiJet 1000 Pump, I want to build a relay for it so I don't have to keep it on or keep plugging and unplugging it, and a couple times I have turned the PC on with the pump unplugged, when I got into windows and seen my temps were in the high 40's I would realize my pump wasn't plugged in, so I rushed and plugged it in.

So I purchased a PC Relay from Radioshack, 12v Coil, able to handle 240VAC. And I knew I would need some wire that could handle high voltage so recycled an old fan (motor burned out):



which left me with a white outlet cord, and two pairs of Grey wire which apparently carried power internally from the top switch down to the motor:


(Also in the picture are some other things not from the fan)

Now instead of trying to wire this mess up and having it catch fire... I decided to ask you guys what would be some good stuff to use to put this together, a good plan that doesn't cost too much. At one time my ideal was to put the relay inside the PSU case and wire it directly to the PSU's incoming supply plug and then slap some kind of outlet on the back of the PSU and plug the pump into it, this way i could use the relay for whatever pump I had and I wouldn't have to chop off the plug.

But now that I look at the back of my PSU, I realize that plan may be harder to complete than originally thought.

So my question to you guys is what should I do?
Hook me up with some advice, Thanks!

You can add additional plug just under PSU or on its back, depending on fans it has. It would take poewr from lines powering PSU.
If wires are insulated properly, all relay parts may be outside PSU.

from what I've gathered its better to actually leave your pump running all the time, as the repeated starting of the motor causes them to wear out faster. (most) pumps used by WCers are pond/aquarium pumps, which are designed to be on all the time to keep little fishies alive .
I leave mine on all the time. I've only been wc a few months now, but I have seen this topic come up before with several people running 24/7 for 1 year or more

Well, for the always on discussion, I guess it all really depends. But as most pumps used have only the impeller as their moving part, it shouldn't matter one way or the other. And how much shorter should turning it on and off make it's lifespan? I use my computer maybe 4 hours a day, so one switch on must shorten it's lifespan with 20 hours for it to makes sense to leave it on..

As for relay, on my previous machine I made it all internal in the PSU. Tapped into the power going into the psu, used 12V to turn on the relay and added a switched internal socket. But my new PSU with a singe 120mm fan has a lot less room, so I'm still working on it.

Tapping power directly from 220V (or 110V) going into the PSU is a good idea, but if space is at a premium, just tap it there and run it out of the PSU. Then make the relay and socket external (as viewed from the PSU)

The realy is simple enough, AC in to the IN terminals, AC to pump from the NO contacts and +12VDC to the coil(if the relay is a 12V one..). And if you want to be fancy about it, hook up a diode to remove transients as the magnetic field in the coil collapses when you switch it off.

It's also a good idea to make a bypass switch so you can fill/bleed/drain without the computer being on.

And make sure to insulate it good, otherwise the probably will be a lot of pretty sparks..

I wired the relay so it plugs it into a molex, left it on top of my CDRW and ran two wires out of the case. Then I cut into the cord from my pump to get to the hot wire so I could run the hot loop through the relay.
I added a 50V, 1A diode to the 12V side of the relay. Why not when they are only 50 cents?
Here's a diagram. My relay looked different so I had to figure out which terminals were what.

iNSiGMA

you may want to have a read of my flow monitoring article as It contains pump relay mod and lots of other related stuff including diagrams, you wont need it all but it should give you some ideas.

http://www.bit-tech.net/article/100/