Lennox furnace with ecobee3 (or nest)

[terknerker (terk)]

Same situation here. SLP98UHV in communicating mode with dying iComfort wifi stat.

However I didn’t spend the money on a fancy XC17 or 21 or 25, I have a simple 13acx single stage non-communicating ac. So my furnace control board has 4 wires in the R i+ i- C to the stat, but the outdoor side is empty. There are two wires coming in from outside going to (i think, i may have forgotten) Y and C on the traditional terminal strip. The icomfort knows the furnace is communicating and the ac is not, so I guess that’s how it energizes only the Y terminal when the icomfort calls for cooling or dehumidifying.

When I pulled my icomfort stat from the wall there are 5 wires, but one isn’t being used.

If I want to switch to an ecobee, will 5 wires be enough? I’m guessing I won’t get to us the ecobee in 2 stage mode with just 5 wires, just single stage and the furnace will be in it’s least useful mode. Being controlled by a single stage stat and using dip switches to use a low burn and high burn setting (compared to variable 35-100% gas valve and variable 35-100% fan speed) and get maybe a couple fan speeds out of it. Kind of like taking a modern 10speed dual clutch auto out of a new car and putting in an ancient 2 speed powerglide lol.I mean it will heat the house but probably be noisy and temp fluctuating.

Is 5 wires enough or do I need more? I was thinking R, C, W,Y1, G. That gives me heat, ac, and fan only right? Then what about dehumidify mode?

As far as the question of converting the furnace to dumb mode from smart mode, I think it ships from the factory with all dips down, and if your installer hooked up to the R i+ i- C terminals then the dip switches are ignored. If you move the wires over to the standard terminals you would have to carefully change several dip switches to set fan speeds, ramp choices, delay, etc. All the things the icomfort does at the stat.

Oh as far as the comment about not having emergency use of the furnace or ac if the icomfort dies completely. I’m pretty sure you could in an emergency, take a cheap thermostat down to the basement by the furnace (well, mine is in the basement), unplug the communicating wires, and wire up your cheap temporary stat to the standard terminals. It wouldn’t be ideal but for an emergency situation at least you could have all the cooling or heating you wanted until you figure out what you want to do permanently.In my case I have a laundry chute in the wall next to my thermostat I could just drop wires down there and still have a cheap temporary thermostat on the main floor.

In fact if it was the middle of the night and the stores were closed, couldn’t you jump R to Y1 to fire up the ac and also jump R to G to run the blower motor? Or maybe the controller board would run the fan itself when you jumped R to Y1. You would have to set some dips maybe to keep the fan from roaring at full speed.

[p_Benware]

Just got finished installing new Ecobee Smart Premium Thermostat on a 2014 Lennox SLP98v and XC17 AC unit. The Lennox iComfort was the 3rd unit to fail. Called the company that did the original install and had previously swapped out the failed iComforts and they wanted nearly $1500 to install the S30, which I just couldn’t do. They also stated that the S30 was the only option available, despite also acknowledging that there are connections, wiring diagrams and instructions for connecting “non-communicating” thermostats. The techs reasoning was that Lennox does not authorize Lennox dealers to install any other thermostat on their products. Not sure how true that is, just what he told me.
Anyway, install was very straight forward. Already had 8 wire thermostat cabling run in the wall to the air handler, and the EcoBee used 7 of the 8. No changes to dip switches, but did clip the W915 jumper to enable 2 stage cooling. Had 5 wire cable from the air handler to the AC unit, of which 4 were used. One item of note is the R and C on the AC unit are the same for both communicating and non-communicating setups; just using the Y1 and Y2 for the EcoBee rather than the i+ and i- (used for communicating thermostats). I had initially skipped connecting the R wire, which resulted in the AC not working, but once R was connected, AC worked fine.
One other note is that I have a condensate pump sitting next to the air handler. This pump has an overflow switch on it which is wired into the R terminal on the air handler. The intent is to disable the system if the holding tank on the pump overflows. Had to research that a bit to figure out the wiring on it, but its all working now.

[Exairbalancer (Mark Kozlowski)]

I also have SLP 98 with a XC 25 unit , gone through 3- 10f81 stats
Outside unit doesnt have a Y2
Did you cut the link on board To get 2 stages of cooling ?

[p_Benware]

According to my previous post I did cut that jumper. I recall thinking at the time that I didn’t want to make a change that was not (easily) reversible but cutting the jumper is easily reversible with a quick soldering job which I’m perfectly capable of doing.
Overall, everything has worked fine, but I miss the seasonal programming capabilities of the previous thermostat.
If I remember and can get a few minutes I’ll take an post some pics of the furnace wiring config.

[celery1124 (Mian Qin)]

I hope this post can help more people get rid of the disgusting Lennox thermostat!!! I have successfully replace my Lennox 10f81 to a Honeywell T9 (or any common Tstats on the market).

I have a SLP98UHV furnace, a XC17 AC unit (outdoor) and a EP-PUMP condensate pump. My 10f81 turned white screen of death last Friday. After reading plenty of people complaining the screen issue (breaks every 5-8 years) and the high replacement cost (an ebay used unit charges $600), I planned to look for another route. Luckily I found this post (special thanks to Brian_Werner) and realized the possiblility of chaging the wiring to conventional wiring which applies to most of the smart/simple Tstats in the market. A few notes in case they help.

• Make sure you read the installation manuals for all your unit (furnace, heat pump, AC, condensate pump, etc). You mainly want to look at the wiring diagrams and the mode tables to understand how the whole system are connected. It’s actually not too complicated.
• Start from the furnace control board and make a complete plan before changing anything. You need to make sure you have enough wires running from the furnace to the wall (Tstats). Check how the outdoor units are connected to the furnace. Draw a simple diagram for your system and carefully label the wires (take pictures) so that you can always revert back.
• The condensate pump wiring confused me at first. But after reading the manual this just act as a fuse and you don’t need to change the original wiring for it.
• The outdoor unit is a bit tricky. But don’t let it afraid you. I believe most of the Lennox system support conventional wiring (non-communicating wiring). You probably just need to move one or two wires.
• All the R and C are the same so you can leave some original connection as it is.

After rewiring (a bit messy):

I forgot to take photos for the outdoor unit, but I only moved one wire (from I+ to Y and unplug I-)

[Mgkacz]

I too have been looking to do this. Appears there have been a number of successful implementations. I have a dual-zone system and I also have a thermostat. Can the ecobee support both of these?

The drawing that Seton_Carmichael posted back in July 202 is very helpful. Anyone else have a similar drawing that I could leverage while I figure out how to migrate as well?

[Kevin_Micheal]

Hello,
I have the Ac unit outside as xc20-060-230-a01 and I want to use my ecobee as my icomfort thermostat is blank and the smart hub is not working

I’m not sure on how to run it out of this 6 pin thing. I think my a/c unit is locked up due to noncommunication. Any help here would be great. I have the ecobee 3 but I only have 5 wires to the ecobee should i try to move it from a 5 wire to 7 instead?