The old furnace had 4 ac wires. 2 coming off a 60 amp from breaker box and 2 coming off 2 thirty amp tied together in breaker box. The new furnace a Miller (Nordyne) has 4 lugs. The top is empty, second one down has a 60 amp breaker, third is empty and fourth has a 60 amp breaker. It came with a single circuit adaptor. Does the two 60 amp wires go to the 60 amp breakers and the two 30 amp go to the empty slots? Should I use the single circuit adaptor? The old furnace was a Intertherm model FEH-015HA-03. Any one who owns the old furnace should check for corrosion. Melted and burned up buse fuse.

Thanks, Doug

Sounds like you have a bigger kw heating element in this new unit if it has 2 60 amp breakers. You may need to unhook a element or run bigger wire.

Should I use the single circuit adaptor?

NO

The unit you have has 2 breakers according to the install instructions below.

http://www.nordyne.com/Literature/708322d.pdf

Follow the instructions

In that model of unit it should have 3 heaters in total. One is on a 20 amp circuit fed by a 30 amp breaker and the other two heater circuit goes on the 60 amp breaker.

Now if your new heater has two 60 amp breakers then something is wrong with that picture because your model number you posted (E3EB-015H ) is supposed to have a 30 and a 60 amp breaker. READ the install instructions and page 22. It tells you what size wire goes to each breaker etc.

That is the correct manual. If you look on page 25 it shows 2 60 amp breakers dual supply. The ad I saw for it said it takes 2 sixty amp and one thirty amp. If the two sixties go to the breakers which lug does the thirty go to? The schematic shows line voltage but not how much. Page 21 shows supply circuit single, Dual A, Dual B is that 3 different ways to wire it up? Also it shows copper wire size, how do you find out the size of the wire? The front of the furnace has a picture across from the breakers. The top says circuit B and shows 2 small wires and the bottom says circuit A and shows 2 larger wires. Glad it is still warm here in Ohio. Thanks for your help.

I had my brother ask at work. The two 60 amp go on the bottom (circuit A) and the two 30 amp go on top (circuit B). Works fine.

Glad you got it going