Mains Pump Relay Guide - Coolercases UK

Leeum · 03-10-2005, 07:47 PM

If like me, your water cooled rig uses a mains powered pump and doesn’t run 24/7, it becomes a pain to have to flick the plug whenever you want to use your computer.

The simplest solution is to buy a pre-made relay… or make your own for the fraction of the price.

What you will need:

PSU
Soldering Iron
Solder
Mains cabling
Wire splices
1N4001 Diode
Relay capable of switching 230V, 12V coil/ solenoid and rated current 5A (to be on the safe side)

Before continuing with this mod, please bear in mind neither I or Coolercases UK can take responsibility for any accidents or damage that may occur as a result. This mod will also void your PSU warranty.

For the record, these reference pictures are taken of an old 250W PSU.
First of all, remove the cover of the PSU, you may also need to remove the fan if you have one on the cover.

The next task is to locate a place for the relay to go. As this PSU has a low wattage and is generally poorly made, you can see there is plenty of space. If your PSU is tightly packed you may be able to glue the relay to the inside of the cover.

Now you must locate the mains power input, as you can see the kettle socket on this PSU has a dedicated PCB.

By looking at the kettle lead socket on the back of the PSU you can identify which points on the PCB are live and neutral.

As you can see, the white wire on this PSU is live and the black wire is neutral. The next task is to solder a length of mains wire onto each of the points on top of the mains PCB which will then go to the relay. You may want to colour code the wires to avoid confusion. Remember, this is mains electricity so make sure you insulate any bear wires with insulation tape or heatshrink!

Now you’ve supplied the relay with the power it’s going to switch, you now need to supply the coil/ solenoid with 12V.

There are two ways of doing this.

You can either trace the wires to the PCB and identify which tracks supply 12V and which are ground and solder two wires to each or more simply, splice two wires leaving the PSU.

There is a good guide on how to splice wires here.

Now it’s time to wire up the relay. The diagram you need to follow is the one below:

Be sure to wire the diode in the wrong way, this is very important! The voltage generated by a relay coil when it's suddenly de-energized can be several hundred volts. The diode essentially stops it from blowing the relay or more importantly…your computer when the pump doesn’t start.

Now that the relay is all wired up, it’s time to test it. You can do this two ways, do the paperclip/ wire trick to the PSU and run the pump (make sure it’s submerged if required) or use a multimeter. Do not run the computer and pump at the same time until you’re 100% happy the pump will start every time.

Hope this guide is useful

Teebor · 03-10-2005, 10:05 PM

Nice One Leeum. I was wondering whether or not to wire straight to my UPS but this would be a much much better idea.

Thanks

**Edit**

I followed your link you gave above to maplins and I was wondering exactly which relay I should be using? The most I have ever used a relay for is 3volt on a remote controlled car so I think its safe to say that I need to be cautious here

I also dont understand all the acronyms but I am guessing that I should be getting the 8pin Rly Skt DIN code (N36AW) ??

Cheers Leeum

**Super Edit**

Thanks Leeum, I'm going to get one tomorrow I think, specially as I have been using it as an excuse to leave my computer switched on

but the vibration from all the loose parts is still annoying me.

I must screw things together

coolmiester · 04-10-2005, 07:40 PM

Good guide Leeum

Leeum · 04-10-2005, 07:50 PM

Cheers guys

Let us know how it goes Teebor.

Teebor · 05-10-2005, 05:49 PM

I'm ordering the relay online now as well as some other toys

Would you believe they dont keep even one 5A relay in store?

I'm just taking a closer look at the molex connectors (I am thinking of modding the whole powersupply into one with the connectors on it) but I am a little concerned about leaving the mains supply one without anything connected, mainly because the pins tend to wobble.

But will keep you up to date, as this is a kickass idea.

Teebor · 13-10-2005, 08:53 AM

Well I finally did it last night, after days of soldering and sweat and tears.

I will be putting it in my worklog and i will post notes and pics here too, but later on as I am busy this morning

Its fantastic though, works really well and now its so compact and all in one place

awesome.

Thanks again Leeum

Leeum · 13-10-2005, 09:32 AM

No probs mate, glad it worked out

Once the 600W Enermax gets here I'll be giving it the relay treatment again

Teebor · 13-10-2005, 05:15 PM

Righto here we go.

I did things a little differently but I would never have done it at all without your guide Leeum

The Pump is an Eheim 1250 pump.

First off I took a live wire feed from the psu connector as above but inserted an inline fuse holder and a 3 amp fuse (the eheim has a moulded 3 amp plug).

This then connected to the relay as shown in the above diagram with the neutral wire.

I then bought the Earth wire around to the molex connector as the eheim has all three wires

(The relay is the clear thing in the bottom left corner)

You can't see the fuse holder as I hid it too well

And a view from the outside

The Relay is near silent and once installed in a PC you probably will not hear it fire at all.

**PANIC STATIONS**

I needed to setup my PC to do a quick video edit for work so I left the main PC running off the spare PSU and connected the fans, pump, and sata HDD's to my modded psu.

I then jumpered the ATX connector to start the PSU and then ran my pc.

I had a slight accident and knocked out the wire I was using to Jumper the PSU so the PC was still running (despite a sudden crash from having no HDD's) but of course nothing was taking away the heat it was still generating.

Fortunately I had done a timed test for the computer to reach an unnacceptable temperature and I knew I had at least 1 minute before meltdown, so I calmly plugged it back in and all was well.

Damn that was close

Leeum · 13-10-2005, 05:23 PM

That's amazing Teebor, the PSU looks much better being modular

The only time you hear the relay is when you first switch the computer on and the solenoid clicks, same with when you turn it off.

Well played!

furqan · 18-02-2007, 03:18 PM

Just a quick few questions

I am wiring up a relay for my pump and just need these q's answered:

1) The diode is wired up so current can go from the ground to the 12v line

2) Can I just split the live wire, connect that to the relay and connect the neutral directly to the pump?

3) Can someone please tell me which connections on the relay are COM and NO

thanks

Edit: Is this diagram okay, I have added a switch to bleed the system, and have only split the live wire:

03-10-2005, 07:47 PM	#1
Leeum Administrator Join Date: Aug 2005 Posts: 1,573	Mains Pump Relay Guide If like me, your water cooled rig uses a mains powered pump and doesn’t run 24/7, it becomes a pain to have to flick the plug whenever you want to use your computer. The simplest solution is to buy a pre-made relay… or make your own for the fraction of the price. What you will need: PSU Soldering Iron Solder Mains cabling Wire splices 1N4001 Diode Relay capable of switching 230V, 12V coil/ solenoid and rated current 5A (to be on the safe side) Before continuing with this mod, please bear in mind neither I or Coolercases UK can take responsibility for any accidents or damage that may occur as a result. This mod will also void your PSU warranty. For the record, these reference pictures are taken of an old 250W PSU. First of all, remove the cover of the PSU, you may also need to remove the fan if you have one on the cover. The next task is to locate a place for the relay to go. As this PSU has a low wattage and is generally poorly made, you can see there is plenty of space. If your PSU is tightly packed you may be able to glue the relay to the inside of the cover. Now you must locate the mains power input, as you can see the kettle socket on this PSU has a dedicated PCB. By looking at the kettle lead socket on the back of the PSU you can identify which points on the PCB are live and neutral. As you can see, the white wire on this PSU is live and the black wire is neutral. The next task is to solder a length of mains wire onto each of the points on top of the mains PCB which will then go to the relay. You may want to colour code the wires to avoid confusion. Remember, this is mains electricity so make sure you insulate any bear wires with insulation tape or heatshrink! Now you’ve supplied the relay with the power it’s going to switch, you now need to supply the coil/ solenoid with 12V. There are two ways of doing this. You can either trace the wires to the PCB and identify which tracks supply 12V and which are ground and solder two wires to each or more simply, splice two wires leaving the PSU. There is a good guide on how to splice wires here. Now it’s time to wire up the relay. The diagram you need to follow is the one below: Be sure to wire the diode in the wrong way, this is very important! The voltage generated by a relay coil when it's suddenly de-energized can be several hundred volts. The diode essentially stops it from blowing the relay or more importantly…your computer when the pump doesn’t start. Now that the relay is all wired up, it’s time to test it. You can do this two ways, do the paperclip/ wire trick to the PSU and run the pump (make sure it’s submerged if required) or use a multimeter. Do not run the computer and pump at the same time until you’re 100% happy the pump will start every time. Hope this guide is useful

03-10-2005, 10:05 PM	#2
Teebor CC Pro Join Date: Aug 2005 Posts: 1,966	Nice One Leeum. I was wondering whether or not to wire straight to my UPS but this would be a much much better idea. Thanks Edit I followed your link you gave above to maplins and I was wondering exactly which relay I should be using? The most I have ever used a relay for is 3volt on a remote controlled car so I think its safe to say that I need to be cautious here I also dont understand all the acronyms but I am guessing that I should be getting the 8pin Rly Skt DIN code (N36AW) ?? Cheers Leeum Super Edit Thanks Leeum, I'm going to get one tomorrow I think, specially as I have been using it as an excuse to leave my computer switched on but the vibration from all the loose parts is still annoying me. I must screw things together Last edited by Teebor; 04-10-2005 at 04:24 PM.

04-10-2005, 07:40 PM	#3
coolmiester Administrator Join Date: Jul 2005 Posts: 3,788	Good guide Leeum __________________ MSN: paul@coolercases.co.uk Laptop Contact: mobile@coolercases.co.uk

18-02-2007, 03:18 PM	#10
furqan Junior Member Join Date: Feb 2007 Posts: 2	Just a quick few questions I am wiring up a relay for my pump and just need these q's answered: 1) The diode is wired up so current can go from the ground to the 12v line 2) Can I just split the live wire, connect that to the relay and connect the neutral directly to the pump? 3) Can someone please tell me which connections on the relay are COM and NO thanks Edit: Is this diagram okay, I have added a switch to bleed the system, and have only split the live wire: Last edited by furqan; 18-02-2007 at 03:33 PM.

04-10-2005, 07:50 PM	#4
Leeum Administrator Join Date: Aug 2005 Posts: 1,573	Cheers guys Let us know how it goes Teebor.

05-10-2005, 05:49 PM	#5
Teebor CC Pro Join Date: Aug 2005 Posts: 1,966	I'm ordering the relay online now as well as some other toys Would you believe they dont keep even one 5A relay in store? I'm just taking a closer look at the molex connectors (I am thinking of modding the whole powersupply into one with the connectors on it) but I am a little concerned about leaving the mains supply one without anything connected, mainly because the pins tend to wobble. But will keep you up to date, as this is a kickass idea.

13-10-2005, 08:53 AM	#6
Teebor CC Pro Join Date: Aug 2005 Posts: 1,966	Well I finally did it last night, after days of soldering and sweat and tears. I will be putting it in my worklog and i will post notes and pics here too, but later on as I am busy this morning Its fantastic though, works really well and now its so compact and all in one place awesome. Thanks again Leeum

13-10-2005, 09:32 AM	#7
Leeum Administrator Join Date: Aug 2005 Posts: 1,573	No probs mate, glad it worked out Once the 600W Enermax gets here I'll be giving it the relay treatment again

13-10-2005, 05:15 PM	#8
Teebor CC Pro Join Date: Aug 2005 Posts: 1,966	Righto here we go. I did things a little differently but I would never have done it at all without your guide Leeum The Pump is an Eheim 1250 pump. First off I took a live wire feed from the psu connector as above but inserted an inline fuse holder and a 3 amp fuse (the eheim has a moulded 3 amp plug). This then connected to the relay as shown in the above diagram with the neutral wire. I then bought the Earth wire around to the molex connector as the eheim has all three wires (The relay is the clear thing in the bottom left corner) You can't see the fuse holder as I hid it too well And a view from the outside The Relay is near silent and once installed in a PC you probably will not hear it fire at all. PANIC STATIONS I needed to setup my PC to do a quick video edit for work so I left the main PC running off the spare PSU and connected the fans, pump, and sata HDD's to my modded psu. I then jumpered the ATX connector to start the PSU and then ran my pc. I had a slight accident and knocked out the wire I was using to Jumper the PSU so the PC was still running (despite a sudden crash from having no HDD's) but of course nothing was taking away the heat it was still generating. Fortunately I had done a timed test for the computer to reach an unnacceptable temperature and I knew I had at least 1 minute before meltdown, so I calmly plugged it back in and all was well. Damn that was close

13-10-2005, 05:23 PM	#9
Leeum Administrator Join Date: Aug 2005 Posts: 1,573	That's amazing Teebor, the PSU looks much better being modular The only time you hear the relay is when you first switch the computer on and the solenoid clicks, same with when you turn it off. Well played!