old Lennox thermostat wiring

______________________________________________________________________ I just buy a townhouse and home inspecter told me the thermostat has to be changed. The old one is a Lennox (sorry no model#), here are wires code : M-red VR- white R-black F-orange V-blue Y-yellow (also connect another red wire) A-green L-brown (also connect another white wire) there were another pair red and white to Y and L. I would like to change a programable thermostat such as Honeywell T8011R, in the T8011R, the wires are G C R W1 Y L W2 E B O Can I use the thermostat ? and how should I connect the wires ? Appreciate for your any inputs.. thank you in advance. Dick Replies: OldTech “Re(1):old Lennox thermostat wiring” , posted Sun 24 Jul 09:00 ______________________________________________________________________ I’m not sure this will help but maybe it will give you a start. Lennox Wiring Conventional Terminal M………………………….Y (Compressor Contactor) VR…………………………R (Hot Side of Transformer) R………………………….O (Reversing Valve) F………………………….G (Indoor Fan) Y………………………….W2 (Aux. Heat) A…. Tape off L…. Tape off V?………………………….C (Common Side of Transformer) OK..Lennox normally used X for the common side of the 24v transformer. V may or may not be connected to the common side of the transformer but I need the common side to the new thermostat. By removing and separating each wire from the old Thermostat and turning power on to the AHU you can check for 24V between VR and V… if it is present you can assume V goes to C. If not, you may need to also rewire the indoor and outdoor unit. Also, on the new T’stat you will need a jumper between Y and W1. dick0309 “Re(2):old Lennox thermostat wiring” , posted Sun 24 Jul 11:31 ______________________________________________________________________ Thank you for your quick respond. So, basically I can use this Honeywell for the replacement ? I posted picture the old wiring in the following link. Hope this can give you more clear picture. Appreciated !!!! Picture here OldTech “Re(3):old Lennox thermostat wiring” , posted Sun 24 Jul 11:48 ______________________________________________________________________ A schematic would help but when I click the link the page is in Japanese or Chinese. Not quite that old:-) Xenos Webmaster “Re(2):old Lennox thermostat wiring” , posted Sun 24 Jul 10:12 ______________________________________________________________________ You have been around awhile :) Xenos. The best way to escape a problem is to solve it.

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