I should also ask if we can eliminate the Novar controls from the unit and just use a regular 24v thermostat. I've been doing some searching on this site about the Novar controls, and I do not believe our customer needs this level of control (nor do I have access to the service tools to connect to it).

The mother boards on the Lennox look identical to some 410a L series we just worked on, and we're using the 'regular' Honeywell VisionPro touchscreens to control those.

 

The Lennox units I have worked on, will have the Novar controller located in it somewhere. It should be clearly marked. The sensor and comm wires goto a terminal block and into the factory wiring harness. The controller plugs directly into the factory harness. You should be able to toss the module and use a standard stat. The outputs are relays driving the G,W1,W2,Y1,Y2 terminals. You may have to do something with the economizer, as the module has direct control of it.

Shoot me an email, and I can send you more info.

 

Thanks. That's kind of what I figured...I see the Novar board on the left side (on the larger units), and figured it was just a digital I/O module. I went through their 'test' where you pull their fuse and jump their relay terminals.

But when I remove their board is there an old plug or jumper harness that would make the terminal block accept a standard stat again like a non-Novar Lennox?

Thanks,
MJB

 

To restore the wiring to the standard configuration:
1. Unplug P16 from the Novar control.
2. Remove the connector that is plugged into J16 in the harness.
3. Connect P16 to J16.

It should be that simple. Just remove the Novar wiring from the TB1 terminal block and attach your t'stat.

 

Yep. That's pretty much what we did today (there was also a small wire for Y1 that was separate). Everything seems to be working fine.

Now we have a bunch of this Novar stuff...Is it worth anything???