3 way switch confusion

Perhaps I'm over thinking this. I plan on have gas fired burners, pid controlled. But, I do want the ability to just run the burner manually. So, I was going to use a 3 way switch with NO contacts for auto-off-on.

Will I go from PID to auto contact block to gas valve, and then straight from 24v source to "on" (manual) contact block to gas valve? Seems like it should be more complicated (maybe because switch came with assortment of NO and NC blocks).

Also planning on going from "out" side of switch to LED light, then to gas valve so the light is on when burner is supposed to be on???

Thanks!!!!

Todd

(you guys are all bad influences ;-) )

Another way I've seen this described is the place the "auto" NO block between the 24v source and the PID "input".

Is there any advantage one over the other?

Todd

Here's one simple way to do it, if you have an On-Off-On switch. For this to work, you need a PID with a relay output. If all your PID has is SSR outputs, you will need to drive a secondary relay with the SSR output.



Brew on

Don't let yourself get confused by the NO / NC options. One side of the switch probably has two NC terminals plus the center hot terminal, and the other two NO terminals. Just hook your two sources to the NO terminals, and your load to the center...... easy as pie. The diagram someone posted is exactly correct.... One NO to the PID, and the other NO to power, center terminal to your valve......... Just pretend the NC terminals aren't even there.


H.W.

This is the switch I bought. No "built in" contacts. So I'll put the 2 NO blocks on each side. I guess there is no way to have 1 line out from the switch? I would need a line from each NO block put to the valve?

http://www.automationdirect.com/adc...a-_Non-Illuminated/Non-Illuminated/GCX3320-22

Todd

NoH20 said:

This is the switch I bought. No "built in" contacts. So I'll put the 2 NO blocks on each side. I guess there is no way to have 1 line out from the switch? I would need a line from each NO block put to the valve?

http://www.automationdirect.com/adc...a-_Non-Illuminated/Non-Illuminated/GCX3320-22

Todd

Click to expand...

For a three position switch, a single block should have two NO connections and a center or common terminal. One NO goes to the power source, the NO goes to the PID, and the common goes to your load. When you turn the switch one way, the power supply feeds from one NO terminal to the center or common as it becomes closed. Turn it the other way, and the PID feeds through the other NO terminal to the center or common. Each connection in normally open until you turn the switch the correct direction.


H.W.

You'll use the two N.O. blocks.

1) Jumper across two terminals, one on each block. This will go to the valve.
2) One terminal to the PID
3) The last empty terminal to 24VDC

If the switch position is not to your liking, swap the PID and 24VDC wires.

'da Kid

Perfect! Thanks guys.

Todd

The10mmKid said:

You'll use the two N.O. blocks.

1) Jumper across two terminals, one on each block. This will go to the valve.
2) One terminal to the PID
3) The last empty terminal to 24VDC

If the switch position is not to your liking, swap the PID and 24VDC wires.

'da Kid

Click to expand...

What 'da Kid said. Did some doodling on a screen cap from the switch spec sheet.



You want the assembly to look like the pic in the upper left, but without the red/orange contact blocks, just the two green ones. I show a jumper across the top terminals, and common goes to the valve.

Brew on

Deleted.

Just noticed 10mmkid beat me to it.

doug293cz said:

What 'da Kid said. Did some doodling on a screen cap from the switch spec sheet.

View attachment 284448

You want the assembly to look like the pic in the upper left, but without the red/orange contact blocks, just the two green ones. I show a jumper across the top terminals, and common goes to the valve.

Brew on

Click to expand...

You are mis-reading the diagram........ ONLY ONE green contact block is needed. Reading the notes at the bottom of the page, you will see that it refers to the right contacts (plural), and the left contacts (plural). It's pretty obvious that we have two switches incorported into each contact block, each with two terminals. Your wiring diagram is correct.... joining the two top terminals..... (or bottom terminals), as common.

Examining the contact blocks, you will find that each contact block has 4 terminals.


Read the notes at the bottom of the drawing.


H.W.

H.W., That has not been my experience with AD's switches.

A good pic of the blocks I'm familiar with is the 2-position switch shown early in the spec sheet.

'da Kid

Owly055 said:

You are mis-reading the diagram........ ONLY ONE green contact block is needed. Reading the notes at the bottom of the page, you will see that it refers to the right contacts (plural), and the left contacts (plural). It's pretty obvious that we have two switches incorported into each contact block, each with two terminals. Your wiring diagram is correct.... joining the two top terminals..... (or bottom terminals), as common.

Examining the contact blocks, you will find that each contact block has 4 terminals.


Read the notes at the bottom of the drawing.


H.W.

Click to expand...

Owly055 said:

You are mis-reading the diagram........ ONLY ONE green contact block is needed. Reading the notes at the bottom of the page, you will see that it refers to the right contacts (plural), and the left contacts (plural). It's pretty obvious that we have two switches incorported into each contact block, each with two terminals. Your wiring diagram is correct.... joining the two top terminals..... (or bottom terminals), as common.

Examining the contact blocks, you will find that each contact block has 4 terminals.


Read the notes at the bottom of the drawing.


H.W.

Click to expand...

Sorry Owly, you're the one who's got it wrong. Each switch block only has provision for two wire connections, so only one contact in each block. Here's an annotated screen cap of a picture of a switch block showing one of the wire insertion slots, and the two access slots that allow tightening the wire clamps.



Brew on

doug293cz said:

Sorry Owly, you're the one who's got it wrong. Each switch block only has provision for two wire connections, so only one contact in each block. Here's an annotated screen cap of a picture of a switch block showing one of the wire insertion slots, and the two access slots that allow tightening the wire clamps.

View attachment 284489

Brew on

Click to expand...

I can see you are right......... The original photo shows a switch with 4 contact blocks, 2 orange and two green and the notes and diagrams pertain to that setup. It's very similar to a switch system I've used before (in appearance), which has stackable contact blocks, but only one contact block at each level..... I used a bunch of these in wiring a mill years ago.


H.W.