New furnace

[HayZee518]

panel & furnace

if you look below the white neutral bar you'll see where the bare grounds connect to.
I looked at home depot and they list a Murray breaker with a 20-40 and 40-20 configuration. stock no begins with MHT.
getting one may be a different story.
in the future you may consider changing out your whole panelbox to a larger, more space board. if you're not ready for a 200 amp 40 circuit panel, they make a 100 amp, 30 space panel.
what you have is a 100 amp 20 circuit spaces filled with tandem or twin breakers.

[lennoxissues]

Perfect. I will make a shopping list based on this thread and hopefully won't have too much trouble tracking down the parts. I may require a bit more assistance when it comes to actually installing them, but this is a great start. Thank you very much.

[HayZee518]

breaker panel

a lot of breakers are interchangeable with each other.
crouse-hinds, westinghouse, murray, general electric, challenger, all will fit your panel. on some breakers the slot that fits over the stab has a rejection type metal clip.
your configuration with the two tandem breakers makes sense now. those larger wires [black and red] are #8's and go
to an electric range.
you get 240 volts from the two twins because they are on opposing stabs on the panel even though they're right next to each other. the two outer poles of the breaker(s) together will give you also 240 volts but separately, 120 volts to ground.

[lennoxissues]

So I have the "armoured cable" which I believe is the BX you were referring to earlier, the box, switch, breaker and even a few feet of thermostat wire while I was at it. The breaker looks like it will fit with no issues, but I have posted a couple pictures. I figure a knowledgeable point of view would be nice in case Eaton isn't a good brand or something. Let me know what you think, thanks.

[HayZee518]

furnace

those two breakers are Ok. thing is their usage in your panel is no good.
you need a two pole 40 for your range within a half sized breaker;
the 20-40 and 40-20 will give you this configuration.
print out your panelbox pictures and take them with you next time you go to the jobber.
twin half sized breakers are ok, full sized breakers won't do.
take 'em back!

[lennoxissues]

Oh, I guess I should have mentioned that they didn't have the 40-20 amp breaker as you suspected they wouldn't. I opted to go with a single 20 amp breaker that would go in one of the two empty spaces at the bottom of the panelbox. I figure that would save me the hunt for the 40-20 amp and I wouldn't have to take that setup out.

[HayZee518]

breakers

Oh! Ok! I didn't see those open spaces - my mistake. Then you're good as gold!

[lennoxissues]

Great. In that case, I just have a few more points to clarify if you don't mind, then I should be able to get this done. First and most important would be how to connect the white wire to the strip in the panelbox. If the power is still on, is it safe to just insert the wire and tighten down the screw? Second, on the new breaker, it looks like it is setup to take a much larger wire that I need, is it ok to just tighten this down on the wire I have? Third, in the box for the switch, there is one screw for grounds, do both the ground from the panelbox and the ground going to the furnace get connected to this one screw? Fourth, the switch has 2 connection points. If I understand the your earlier explanation, the white wires get connected within the box, then the black from the panel box goes to the top of the switch and the black wire to the furnace goes to the bottom of the switch? And finally last, the ground wire coming out from my new furnace is an insulated wire consisting of strands, where the ground from the BX is bare and solid. Is it ok to connect these? Sorry about all the questions, but after this I should have all I need to get this done. Thank you.

[HayZee518]

furnace wiring

I drew the following the best I can for you. it shouldn't be as bad as it looks.
Material List:
2 - armored cable connectors
2 - romex cable connectors
4 - 1/2" locknuts
2 - 4" square by 1 1/2" deep junction box
1 - single switch 1/2" raised 4" square cover
1 - 4" square blank junction box cover
1/2 doz yellow ideal wirenuts
1 - 20 amp rated switch
1 - 1/2" x close pipe nipple
screw, mounting hardware etc.

[lennoxissues]

Alright thank you. Tomorrow morning I will get started with that and hopefully all will go well.

[lennoxissues]

One last and important thing. How do I safely secure a white wire to that strip in the panelbox. Wouldn't it be live? Or is there an order to do that in, maybe the white wire to the panelbox strip should be done first, or last. Besides that, I think I am ready, just don't want to BBQ myself.

[HayZee518]

panelbox

the neutral strip is at ground potential - zero volts.
the only way you'd feel anything is if you remove an existing white on an active circuit and somehow got your fingers between the neutral bar [or chassis] and the white wire.
the white wire carries the imbalance of the load to ground.
find a free hole on the strip and insert both wires into it and screw down the screw.
which order you do that doesn't matter.
if you have no holes, usually the hole is big enough to insert at least five wires into it.
as for your other question, the binding screw on the breaker and its hole is big enough to insert a #6 solid or stranded wire.
the twelve you're putting in there will be securely fastened so don't worry 'bout it.

[lennoxissues]

Ok, I will get stated with all that right now. My main concern was being electrocuted, but I am relaxed now with your explanation. Thank you again for all the help and suggestions. Hopefully I can pay it forward at some point on this site.

[lennoxissues]

So I think I am about ready to fire this thing up, just have a question about the thermostat wiring. I only have three wires, 2 of which are self explanatory, but the white wire has the option of "W1" and "W2". The manual says "W1" is "Heat demand from 1st stage T/Stat" and "W2" is "Heat demand from 2nd stage T/Stat" My assumption is that I would use "W1" as I only have on thermostat. I'm just concerned that this will in some way effect the dual stage gas valve.

[HayZee518]

furnace

I was never too good with furnace low voltage controls, although many of installations worked!
you said W1 and W2. the thermostat is usually annotated TH1 and TH2 on the gas valve relay.
try it and see what happens.
it it a honeywell thermostat or a lennox stat?