Old electric furnace wiring

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Old 12-01-18, 06:26 PM
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Lightbulb Old electric furnace wiring

I have an old Singer furnace from back in the early 70's and no wiring diagram. I was restoring it as a project and to provide heat this winter and the days are getting colder ...

I have the furnace wired up and was looking to verify that I have the 24v wiring correct.

Note: I also have a 3 amp fuse on the red wire before it goes to the thermostat.
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Old 12-01-18, 07:37 PM
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That is a basic electric furnace diagram and will work. You need to make sure the G terminal is active in heat mode. Usually it's not. The stat may have a switch on it for electric heat.

Typically on an electric furnace..... the G terminal is used to activate the blower by itself and the sequencer controls the blower in heat mode. This is done so that the element is shut off and the fan runs for an additional amount of time to cool the elements.

Be sure you have a high heat limit switch in the electric element line in case of blower failure.
 
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Old 12-01-18, 09:25 PM
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When I switch the thermostat to HEAT does it send voltage to the GREEN and WHITE wires?
 
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Old 12-01-18, 10:11 PM
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It needs to. You need to check the stat for a GAS/electric heat switch or electric heat in programming.
You can post the model number of the stat for more info.
 
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Old 12-01-18, 10:15 PM
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Lightbulb Electric Furnace Heater Coil Wiring

I can't remember how the coils were wired. Here is how I have them wired currently but not sure if it is right or if I should swap A and B or if it matters at all. I'm thinking it should work either way right?

Having trouble getting my heater coils to come on and trying to locate the problem.

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Old 12-01-18, 10:19 PM
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Keep all your work on this furnace in this thread.

A 5000 watt element would not be 120v. It would be 240v.
 
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Old 12-01-18, 10:25 PM
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It needs to. You need to check the stat for a GAS/electric heat switch or electric heat in programming.
You can post the model number of the stat for more info.
There is a switch in the back and it is set to electric.

Thermostat Model is Honeywell RTH2510 / RTH2410 Series
 
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Old 12-01-18, 10:32 PM
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Keep all your work on this furnace in this thread.

A 5000 watt element would not be 120v. It would be 240v.
OK I'll keep it in this tread and thank you for your help

The 24v system seems to work because the fan switch works and is kicking the fan on.
I'm going to wire in the transformer soon and then I'll be able to test the 24v at the base of the sequencer soon.
The heater coils were coming on a few weeks ago when I tested it but stopped working.
 
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Old 12-01-18, 10:39 PM
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A 5000 watt element would not be 120v. It would be 240v.
This could be a part of the problem because I'm running 120v to one side of the Sequencer and 120v out the other side to the coil. Maybe I should be running 2 - 120v wires to the sequencer.

The fuse block is divided into 2 sections with 120v.

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Last edited by PJmax; 12-01-18 at 11:20 PM. Reason: new diagram
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Old 12-01-18, 11:19 PM
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You need to stop thinking of two 120v lines. You are working with 240v.
Two 120v legs don't always yield 240v.
You need a line from Leg A and a line from Leg B. Yes..... individual they are 120v but if you had two 120v lines from Leg A..... that would not yield 240v.

I redrew your diagram.
 
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Old 12-01-18, 11:46 PM
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Two 120v legs don't always yield 240v.
The Fuse Block is divided into two sections each side is 120v.
So trying to think how I can run 240v lines to the sequencer.

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Maybe I'm misunderstanding and your saying that A and B totals 240v to the heater coil?
 

Last edited by Toolman Dan; 12-02-18 at 12:12 AM.
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Old 12-02-18, 12:06 AM
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Measure across the two blocks. You should see 240v.
 
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Old 12-02-18, 12:21 AM
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Measure across the two blocks. You should see 240v.
Yes but they are 2 separate sections that are not joined together so if I run a wire to the sequencer it is showing as 120v. But maybe I'm misunderstanding and your saying that wires A and B are feeding the coil and totaling 240v? If not I need to find a way to create 240v from the fuse box. Sorry I'm somewhat new to this if you didn't notice lol.

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Last edited by Toolman Dan; 12-02-18 at 12:37 AM.
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Old 12-02-18, 12:25 AM
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Only one line gets switched. Look at the drawing I did. One line goes to the element. The second line goes thru the sequencer. The red is one 120v path and the black is the other 120v path.
 
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Old 12-02-18, 12:39 AM
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Only one line gets switched. Look at the drawing I did. One line goes to the element. The second line goes thru the sequencer. The red is one 120v path and the black is the other 120v path.
OK I'm sorry I was misunderstanding you. Thank you for explaining it to me.
I'll make these changes and get back with you. Hopefully the elements will come on this time.
 
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Old 12-02-18, 08:22 AM
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Smile Fan Wiring

Typically on an electric furnace..... the G terminal is used to activate the blower by itself and the sequencer controls the blower in heat mode. This is done so that the element is shut off and the fan runs for an additional amount of time to cool the elements.
OK ... so here is how I currently have the Fan layout. I'm jumping the fan from the sequencer so that the fan stays on until the heat from the 24v cools down at the base of the sequencer and finally shuts off the elements. Let me know if I have to correct anything.

Additional Note:
I'm using the BLACK wire from the fan which currently is giving me the fast speed. I did this because I replaced the old coils with new ones and I fear that they will burn up. I was reading that when the heat runs it is supposed to be the RED wire which is the one step down from the fast speed. Is it OK to use this speed until I feel more comfortable and then step it back down?

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Old 12-02-18, 11:39 AM
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Red face Update

The elements came on but the fan shut off way too soon.
The elements were still glowing after the fan shut off.
 
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Old 12-02-18, 02:05 PM
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In order to accomplish what you want...... you need to replace your single pole relay with a single pole double throw. As shown in the diagram..... when there is no power on the G terminal..... the relay is normally closed. That will allow the sequencer to control the blower. When you power the G terminal..... the fan will run. Change the stat programming or switch back to gas furnace and the G will not be energized in heat mode.

With a 5kw element..... medium speed should be ok. You'd have to monitor the high heat safety stat. You don't want it opening when the furnace is running normally.

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Old 12-02-18, 03:54 PM
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Unhappy Single Pole Double Throw

you need to replace your single pole relay with a single pole double throw
Ok .... using Single Pole Double Throw switch.

Change the stat programming or switch back to gas furnace and the G will not be energized in heat mode
I changed the stat back to gas furnace.

I wired the fan switch just like the drawing and I blew a fuse.
The fuse that blew is where the wire runs from the fuse block to the sequencer.
 
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Old 12-02-18, 03:56 PM
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I can't help you on the specific sequencer wiring without it's full part number. Every one is different.
 
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Old 12-02-18, 11:06 PM
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I can't help you on the specific sequencer wiring without it's full part number. Every one is different.
You've been a BIG help and I really appreciate it!!

I'm going to try and restore the wiring diagram. The blower caught on fire 10 years ago and the diagram has mold and fire damage from that fire. I'm thinking that the wire arrangement at the fuse box is EXTREMELY important and has something to do with the fuse blowing. Balancing this load at the fuse block is probably REALLY vital. I'll get back with you.
 
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Old 12-03-18, 02:01 AM
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Lightbulb Fuse Block Load Balancing and Wiring

Singer BCE23000
Date 9-12-73

The wiring is close to matching furnace diagram.
Looks like there was some load balancing too.
The original diagram shows a 6 pole fan switch.

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