How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask servtech50 Your Own Question
servtech50, HVAC Technician
Category: HVAC
Satisfied Customers: 322
Experience:  over 20 yrs. experience
Type Your HVAC Question Here...
servtech50 is online now
A new question is answered every 9 seconds

how to wire the 24v transformer to the relay y w c g r

Customer Question

how to wire the 24v transformer to the relay y w c g r and the red and white wires from the thermostat just want to be sure thanks new question ill look forward to your answer thanks again
Submitted: 5 years ago.
Category: HVAC
Expert:  servtech50 replied 5 years ago.

servtech50 :

Hello, and welcome to Just Answer. I am servtech50 and I will assist you today.

servtech50 :

It sounds like you have a fan center. Is this true?

servtech50 :

if it is then you only have to wire the black and white wire to line voltage and the transformer will energize making the red terminal on the back hot with 24 vac.

servtech50 :

then from your gas valve the "TP" wire would connect to the "C" terminal and the "TH TP" wire would go through, possibly, a safety limit switch then to the "W" terminal along with the white from thermostat. The "W" teminal does nothing with the relay, the relay is for switching fan speed to A/C. Your blower should energize via Fan/limit control.

servtech50 :

If I am incorrect in assuming this is a fan center then I would need more information because I have never seen a relay marked y w c g r. Please let me know. servtech50

Expert:  servtech50 replied 5 years ago.
Oh yes one more thing, the red wire from thermostat would go to "R" on terminal board and white from thermostat will go to "W" on terminal board along with the wire that goes to the "TH TP" on gas valve.
Customer: replied 5 years ago.
this is an on going saga this is a becket burner on a bard forced hot air oil furnace ,wanted to replace the oil primary the new primary has a wire for limit that needs 120v the old one wascontroled by the thermostat get power to the limit a relay was put in with 2 going to the limit on the new controler 4 going to l1 black power wire,there is a transformer on the furnace already it has 5 terminals the c has a blue wire on it sodoes the g thereis a w r y that have no wires i want to hook the red and white wires to this trans former to control the new relay
Expert:  servtech50 replied 4 years ago.
Does your new primary still have the "T T" terminals? and either the "F F" or "C C" terminals? If so, the "T T" is for thermostat and the other for cad cell, the burner gun "eye". What you could do is the one line to your 120 vac limit is connect your incoming line voltage, the line from breaker box. The other line from your limit wire nut to the guns motor lead. so when or if the limit ever trips the gun will shut off thus no oil for flame. The other transformer is for added A/C, it is called a fan center. If you want to use this transformer take the plate off the 4x4 electrical box. there will a black and white wire connect them to your incoming line voltage. there will be two other wires or possibly one. if you look at the relay on the back side of the transformer you will see 3 or 6 spade connectors. if 3 great, if six you are only concerned with the set that the one or two wires go to. But if you look at that relay you will see electrical signs that represent normally open circuit and a sign that represents normally closed circuit. so there will be a spade connector to the left (line voltage from breaker), one in the middle (normally closed) and one to the right (normally open). The normally open wire should connect to the 120 vac wire that goes to the gun and new primary. You would the connect your thermostat wire red to "R" and white to "G". that will energize the relay on the back side of the fan center closing the "normally open circuit" and thus sending the line voltage to the primary. if this does not make any sense or if I am not reading correctly will you send me the model number of the new primary? I can then look up the wiring and get a better feel for what needs to be accomplished. servtech50
Expert:  servtech50 replied 4 years ago.
Thinking about this a little more. If the fan center came with the furnace then all the wires may be connected to something. That normally open spade connector that I mentioned before may have a blower wire connected to it. That wire would increase the speed of the blower if you were to install A/C. if there is a blower wire connected there or to the wire that comes from that side of the circuit (most of the time a brown wire) un wire nut then cap the blower lead and wire your single lead from limit to that relay lead. Just remember you have to use the circuit from the fan center relay that is normally open. The thermostat wires will remain the same red to "R" white to "G" do not remove the blue wire going to "G" and to the back of plate. servtech50
Customer: replied 4 years ago.
the new primary is r7284u ihave a wire conecting the tt terminals there are 2 wires for the cad cell the transformer is connected w to white on thermostat and 1 on relay c goes to 3 on relay and r is to red wire on thermostat the g has a blue wire already connected so does the c the heat comes on normally with the thermostat but it seems to shut off because the fire box is getting too hot thanks the relay im talking about is new from the dealer who sold me the r7284u it is to bring 120v to the limit in the controler when the thermostat calls for heat via the transformer
Expert:  servtech50 replied 4 years ago.
ok, I have looked at the wire schematic and I have a thought on how to wire. But I have to leave on a service call, when I get back I will put thought to paper. servtech50
Expert:  servtech50 replied 4 years ago.
ok, I have looked at the wire schematic and I have a thought on how to wire. But I have to leave on a service call, when I get back I will put thought to paper. servtech50
Expert:  servtech50 replied 4 years ago.

Starting with your low voltage (24), from thermostat it sounds like you have it correct. Red wire to "R" terminal on transformer. White wire to coil on new relay. Then an added wire from new relay coil to "C" on transformer. This will energize the new relay when there is a call for heat. Jumpering the "T T" on new primary good.

Now, line voltage. you have 120 vac coming into furnace, most of the time they use a light switch for the disconnect at the furnace, does yours have this switch so you can turn on and off? From there it should go into the back side of the transformer into a 4x4 electrical box. The white wire will or should stay neutral all the way through the wiring of furnace. The black will have at least 3 more wires wire nutted with it. 1. will be for the transformer the 2nd will be for the fan limit and the 3rd will be for the burner gun. since we are not using the relay from fan center we will not deal with any other wires behind the transformer. The wire going to the fan/limit is the wire I wish to deal with. Do you know what the fan/limit is? where it is located in your furnace? and what it does? Basically, it is the control switch that turns your fan on when the furnace gets to the set temperature. And it is also your furnace "LIMIT" switch. If your blower fails or if you are not moving enough air because of a dirty filter the fan/limit will rotate to the end and power would be disrupted and burner will turn off. There are two sides to the fan/limit, the left side of dial is you fan side. Bottom wire should be line voltage coming in and right above that should be a wire that goes to you blower motor, marked "fan".

To the right of the dial is the "limit" side. I hope the internal jumper is still intact so there isn't any wire on the bottom. Only the one wire on top in the marked "limit" slot. Is this the case? If there is a wire connected on the bottom right please, if you can, check the voltage and see if it is line voltage or low voltage. If line voltage we are still good. Now may I ask, did the person you bought the primary and relay from want you to control the furnace by opening the limit circuit or the main power to gun circuit? If you open the limit circuit to turn the furnace off you should always get a limit code at the new primary. if you turn power off to gun then it just turns off. I am going to stop here because I would like your feed back on the questions I have asked. But please keep in mind, The new primary does not have a limit in it, other than the cad cell circuit. The wire, red if I remember correctly, is to go to an external limit. So it is important that you answer my questions. I will be online as long as possible this morning but will be back on later this afternoon. servtech50

Expert:  servtech50 replied 4 years ago.
I see by your log ins that you are up late at night. to bad we cannot meet at same time. You did not answer my questions so I was wondering what became of the issue. servtech50
Customer: replied 4 years ago.
sorry computer had issues just worked them out had no electricity for 5 days heat is working but i smell oil but after not having heat im afraid of messing wyth it i need time to read your answer thank you i will gfet back to you this week thanks again

Related HVAC Questions