Detroit ca295 relay/transformer

robw203

The relay on my old American Standard boiler got stuck "on" and the heat is running hard. I replaced the thermostat and no joy. The Detroit relay is no longer available so the supply house sold me a modern equivalent. I am unsure of how to wire it. Can someone guide me through the adapting?
Thanks!

robw203

The new one!

EBEBRATT-Ed

I would have to see the wiring diagram of the old control to be sure.

I can give you some idea but I am guessing:

R & W the red and white wires (on the old control) I would think come from your thermostat those would go on R(T) & W (T) on the new control.

#1 black wire on old would go to L1 on the new control
#2 white wire on old would go to L2 on new control

Now I have to guess. The red/brown?? wire on #3 in the old control I am guessing goes to your circulator pump (if it is a hot water boiler). That would go to #NO on the new control. You would also have to put a permanent jumper wire from terminal L1 on the new control to #com on the new control.

Now the other wires at the top of your old control S, S &G I would guess go to a gas valve on the boiler.

The may go on X X and C on the new control but that is a wild guess.

To really know we need the diagram from the old control inside the cover or you need to trace some wires and see where they go (probably some of both)

mattmia2

can we see the gas valve on the boiler too? this might be an old power open power close motorized valve.

Steamhead

W, G and R probably went to an old 3-wire thermostat.

S and S are probably a switch contact that switches 24 volts to the gas valve.

@robw203 , where do the two 24V cables go from the top of the relay? What thermostat do you have?

109A_5

Hello @robw203,
Did the old one get wet ? If so the new one won't last long if it gets wet too.
Is the wiring diagram of the old one on the inside of the cover ?

EBEBRATT-Ed

@Steamhead

Sticker on old control says do not use with 3 wire stat. But the picture @109A_5 posted has a note about a Detroit 3 wire stat

@robw203

I would onit the G wire if you have a 2 wire thermostat.

I would still want to see where the S & S wires lead to. They probably go to X & X

Everything else I posted above should be ok

robw203

Appreciate all the guidance, have to look at everything closer. No wiring diagram on old unit but a few forums had diagrams of how to make the switch. Just have to survive the holidays and I'll get after it. Thanks for all of your input 

HVACNUT

robw203 said:

Appreciate all the guidance, have to look at everything closer. No wiring diagram on old unit but a few forums had diagrams of how to make the switch. Just have to survive the holidays and I'll get after it. Thanks for all of your input 

Find out where those SS wires go.

EBEBRATT-Ed

@HVACNUT
The op hasn't said whether he has gas or oil or boiler or furnace. But the note on the old relay says to wire "S" & "S" to "pilot terminals of stack switch "R" & "W" which would indicate an oil stack switch. It would make sense the stat pulls in the relay starts the circ pump S & S make and fire the burner.

Some posters it's a little like pulling teeth.

EdTheHeaterMan

This is the internal wiring of the Detroit Switching Relay. I believe the center low voltage (TOP) terminal is the C of the transformer. So S S is the same as X X and terminal 1 goes to terminal 3 when the 1K relay coil is energized which closes the 1K1 and 1K2 contacts. 1K1 connects the S to the other S and the 1K2 connects terminal1 to terminal 3.

EdTheHeaterMan

Here is the terminal designation cross reference

EBEBRATT-Ed

@EdTheHeaterMan

Good info. That is pretty much what I had figured. G on the Detroit control looks like that wire goes down inside the control so it must be the common coming out.

The S & S terminals looks like there are 2 wires on each so which look like all 4 come in in low voltage cable so I would like the op to find where they go.

Could be they go to an oil stack control but that leaves 2 extra wires. need to know what he has.

robw203

The solution...thanks and happy holidays

EBEBRATT-Ed

@robw203

Did it work?

EdTheHeaterMan

What @EBEBRATT-Ed asked? @robw203