wiring relay for radiant floor heat pump

[rybopp]

hello
I am trying to figure out how to wire up a relay that will be controlled by a thermostat to switch on the circulating pump for a radiant floor heating system. The relay is an 8 pin NTE DPDT 10A-12VDC. I cannot figure out which "side" (pins) should be hooked up to the 12vdc coming through the thermostat and which pins should be hooked up to the 120ac that will turn on the pump. I know very little about electronics and the diagrams but the relay has a base which makes it easy to hook up the wires. I am assuming that the 12 volt side would be wired as NC because the thermostat will be the switch on that side. Also assuming that the AC side will be wired NO, so that power will only be supplied to the circulating pump when the DC side is powered.

The pdf for the relay should be attached. Part# R02-11D10-12
tia
ryan

 

[tunedwolf]

Pins 2 & 7 require your 12V through the thermostat, Pins 1 & 8 get the 120V supply and Pins 3 & 6 go to the pump.

The Relay base you have will most likely be numbered to match your Relay pins, i.e Pin 1 on the base will go to Pin 1 on the Relay etc, but it could also be marked A1 & A2 for the coil pins depending on what manufacturers socket you have. All of the NTE sockets I have seen are marked Pin for Pin.
If in doubt, remember that the polarisation keyway in the middle of the socket points between Pins 1 & 8, if you hold the socket with the keyway pointing towards you, the pins are always numbered counter-clockwise.

The Thermostat is normally open, therefore the Relay is not normally energised, ergo neither is the Pump.
When the Thermostat closes, i.e the measured temperature drops below it's set point, the contacts on the Thermostat close, passing the 12V to the Relay coil, thereby energising it. When the relay contacts close the 120V supply is fed to the pump.

If the Pump has an Earthing (Grounding) point, make sure you carry an Earth (Ground) wire to it along with it's wires from the Relay. Put the Relay and associated socket in a plastic box, with a lid that can only be removed by undoing screws, and gland/strain relieve the cables going into and out of the box. Mount the box on the wall well out of the reach of water.
It will also be a good idea to put a fuse holder in the box with the correct rating of fuse for the pump, take your 120V supply to the fuse and from there to the relay and your 12V power supply, that way if something goes wrong, it's not going to cause a fire or anything.

Hope this helps you out

 

[rybopp]

it seems so obvious now

that 2-7 are the pins for the 12v electromagnet...I just didn't know the schematic symbol for such...this is the relay the guy at the local electronics supply shop gave me when I told him what I wanted to do...it seems that I could have used a relay that only had one set of NO/NC pins, is that correct? I'm guessing that this relay is designed to switch 2 separate loads if need be...do I really need to wire both sets (1-3, 8-6) or would one suffice? just wondering...

thanks a bunch for your assistance t-wolf...and thanks for the tip on adding a fuse too...a good thing to do that I hadn't considered...

 

[tunedwolf]

I would personally use both sets, purely for isolation purposes, there is a quite often a small difference in potential between local electrical Earth (Ground) and Neutral, so it's preferable to have a double pole break just for safety's sake.

Pins 2 & 7 are indeed the Electromagnetic coil connections.

One thing I forgot to mention earlier, because for some reason I just figured you would be using an A.C Relay, i.e one designed to be energised by an A.C voltage rather than a D.C one. If you are using a Relay designed to operate on D.C, then put a 1N4007 diode across the coil with the Cathode going to the positive side, imagine the symbol for a diode, should look something like
Anode -->|-- Cathode - now imagine this as an arrow pointing towards the positive supply. The reason for the diode, is that when the current makes and breaks at the Relay coil, an largish voltage spike is developed in the coil and this will be presented to the power supply. The diode makes this voltage go round the coil instead, and allows the coil to dissipate it rather than damaging the power supply.

I wish you well with it, if you need any further help let me know...

 

[rybopp]

many thanks t-wolf!

greatly appreciate your assistance...
ryan

 

[rybopp]

hi tw...just a note to say after getting sidetracked for a few months I finally got around to hooking this up...works fine...much nicer than switching the breaker....lol...thanks again for your able assistance...
ryan