Which relay should I buy???

[Huskurdu]

I'm showing a switch power of 27 volts AC that I want to use to trip one of my 110 volt circs on. I thought it was odd that it is ac and not dc? Any thoughts on which relay I should buy or any other ideas about this project? I want something cheap, simple, and reliable...not necessarily in that order. Thanks, np

 

[Former Farmer]

Providing that your pump is only drawing a couple of amps, I would use what I refer to as an ice cube relay. They can come in many different configurations. You need one that has a 24VAC coil. You would also need a socket (base) to plug relay into. Grainger part# 1EHK5 and 1FC13 - would be examples. If you need higher amperage, than you would need a heavier duty relay.

 

[Huskurdu]

Yes, it's just a Taco 007 running at about 1 amp so that should work. I have ordered on Grainger's site and hopefully I'll have the two pieces early next week to try them out. Thank you very much for the reply with part#'s, that really simplified the process.

np

Providing that your pump is only drawing a couple of amps, I would use what I refer to as an ice cube relay. They can come in many different configurations. You need one that has a 24VAC coil. You would also need a socket (base) to plug relay into. Grainger part# 1EHK5 and 1FC13 - would be examples. If you need higher amperage, than you would need a heavier duty relay.

 

[seige101]

I'm showing a switch power of 27 volts AC that I want to use to trip one of my 110 volt circs on. I thought it was odd that it is ac and not dc? Any thoughts on which relay I should buy or any other ideas about this project? I want something cheap, simple, and reliable...not necessarily in that order. Thanks, np

I just happen to have a solution that is all 3. http://www.functionaldevices.com/pdf/RIBU1C.pdf

It's a relay in a box, the coil will accept multiple voltages. It's a nice clean setup, install right off your controller box.

About $30 bucks at your local electrical supply house. Not a big box store.

Better yet order from grainger here http://www.grainger.com/Grainger/items/5LE35 $ 25 bucks

 

[sgschwend]

Actually you really want AC, it protects the contacts better.

 

[Gooserider]

The main reason you will see AC rather than DC in a lot of heating control applications is that AC is easier / cheaper to make, and some ways easier to wire, so unless you have things that require DC, why bother?

It is easy to change voltages going AC to AC, all you need is a simple transformer. If you want to make it into DC you have to rectify and filter the AC which is an extra step and added hardware. To change DC into another voltage you have to go through a lot more complex set of steps, which are either energy wasting, or expensive, if not both...

With AC wiring, while normally one worries about polarity for safety reasons, you don't have the same problems of wiring it backwards with AC - swap the wires around and it will still work fine.

AC is a little easier on switch contacts and the like, although it isn't a big deal as DC can be handled fine with the proper design.

If you do need DC, it can be easier to do a local "point of use" transformer / rectifier that makes just the amount of power needed for that function rather than trying to have a larger transformer to make enough for the entire system.

Gooserider

 

[Huskurdu]

Thanks all for the advice. I did purchase the Grainger parts listed in the second posting. It sounds like that should work for me. Gooserider you are right below (not that I doubted you ) I thought it was going to be harder because it is AC, but it looks like no big deal.
Do you guys think this relay socket can be mounted to a piece of plywood so that I can hang it near the circ or should I buy a metal box to house it? I'm not looking for aesthetics, I'm looking only for safety and function.

np

The main reason you will see AC rather than DC in a lot of heating control applications is that AC is easier / cheaper to make, and some ways easier to wire, so unless you have things that require DC, why bother?

It is easy to change voltages going AC to AC, all you need is a simple transformer. If you want to make it into DC you have to rectify and filter the AC which is an extra step and added hardware. To change DC into another voltage you have to go through a lot more complex set of steps, which are either energy wasting, or expensive, if not both...

With AC wiring, while normally one worries about polarity for safety reasons, you don't have the same problems of wiring it backwards with AC - swap the wires around and it will still work fine.

AC is a little easier on switch contacts and the like, although it isn't a big deal as DC can be handled fine with the proper design.

If you do need DC, it can be easier to do a local "point of use" transformer / rectifier that makes just the amount of power needed for that function rather than trying to have a larger transformer to make enough for the entire system.

Gooserider

 

[Gooserider]

Thanks all for the advice. I did purchase the Grainger parts listed in the second posting. It sounds like that should work for me. Gooserider you are right below (not that I doubted you ) I thought it was going to be harder because it is AC, but it looks like no big deal.
Do you guys think this relay socket can be mounted to a piece of plywood so that I can hang it near the circ or should I buy a metal box to house it? I'm not looking for aesthetics, I'm looking only for safety and function.

np

Depends on what you are switching, and how exposed the terminals are. If it's all low voltage, then a box isn't required, but it probably wouldn't hurt. If you are going to be switching 110 or 220V AC then code REQUIRES that you put the relay in a box. Similarly, if your relay socket has exposed terminals, putting it in a protective box is a good idea, regardless of the voltages involved.

Gooserider

 

[Huskurdu]

[/quote]

Depends on what you are switching, and how exposed the terminals are. If it's all low voltage, then a box isn't required, but it probably wouldn't hurt. If you are going to be switching 110 or 220V AC then code REQUIRES that you put the relay in a box. Similarly, if your relay socket has exposed terminals, putting it in a protective box is a good idea, regardless of the voltages involved.

Gooserider[/quote]

Yes, I'll be switching 110volt so I'll get an enclosure for it.

thanks again,
np

 

[sgschwend]

Actually the contacts in a switched AC signal last longer than DC.

 

[Huskurdu]

Providing that your pump is only drawing a couple of amps, I would use what I refer to as an ice cube relay. They can come in many different configurations. You need one that has a 24VAC coil. You would also need a socket (base) to plug relay into. Grainger part# 1EHK5 and 1FC13 - would be examples. If you need higher amperage, than you would need a heavier duty relay.

You 'da man! I got the ice cube relay installed last night....works like a charm! Thanks again for your help.

np

 

[Former Farmer]

Glad that worked for you. Happy heating.