Lennox G61 mpv With a single stage stat

**koen** · 11-25-2005, 08:10 PM

I have seen many posts talking about whether or not you need a multistage or 2 stage stat with a 2 stage furnace. BUT! They don't fully answer my question. I want to know if my honeywell CT 3500 single stage stat will run my Lennox G61 MPV properly.
This is the second furnace I have bought in the last 2 years. I had put one in my old house a Carrier 58 MPV Which I found to be more efficient when it came to heating the house fast and not kicking in as much. Well since then I moved and bought a house that needed a new furnace, seeing as I moved to a new province the Prices were dramatically reversed and I ended up putting in the lennox. So far not too happy with it. Could it be the Thermostat being a single stage??? And if so?? when I buy a multi stage stat, I only have four wires to hook up, should there be a second for the 2nd stage??? totalling 5??

excuse my lack of knowlege on the lingo and mechanics, but thats why Im here!
any feed back would be great thanks!

cK

**tinknocker service tech** · 11-25-2005, 08:21 PM

your stat will work fine as long as the furnace is set up properly. the furmance will time on second stage heat after about ten minutes of demand. this time soan can be a justed and the blower can also be set up to give the air flo needed at both stages. have the installer come back and make the proper ajustments to the furnace so you can get the most out of it

**BaldLoonie** · 11-25-2005, 08:22 PM

Why buy a top of the line furnace and cripple it with a cheapo single stage stat. Do a search on 2 stage stats and you'll find very few pros recommend not using them!

**koen** · 11-25-2005, 10:03 PM

Good point about the stat! I was looking at a Honeywell 7 day touch screen, but even at that its just a home depot one.

If I am to install the better stat does only 4 wires sound right for the 2 stage ??

And I called the company back and they sent out a tech, and he said everything was hunky dory and wasnt sure why I was wondering about it.

He told me to adjust the cycle times on my stat, so on the Honeywells it comes preset at 6 so I switched it to 3 as set out in the directions. I dont really notice a difference.

I know the lennox is different than the Carrier, but the Carrier you could actually tell when the second stage cut in and the blower increased. The lennox seems to rev up with the variable speed motor, but stay at the one speed and not increase even if I crank the stat.

[Edited by koen on 11-25-2005 at 11:31 PM]

**t527ed** · 11-26-2005, 10:52 AM

if house has a/c at least 5 wires for 2 stage heat, 6 wire if 2 stage a/c also could be more depending on stat. pull more than you think you need. lennox sig stat matches nice to that heater and will let you control humidity by ramping v drive blower down.

**Milk man** · 11-26-2005, 06:17 PM

The lennox has a timed on second stage while the Carrier time the total length of the heating call. It then varried the low and high fire lengths based on the amount of time it took to satisfy the single stage state.

The Carrier had a personality plug that set the heating airflow cfm while the Lennox's circuit board has to be set by someone that can read and understand the installation and operating manual. And for cooling airflow the carrier board was simple to set. It has dip switches crossed to the size of the outdoor unit. The Lennox has dip switches crossed to CFM. Here again the start up tech needs to be able to read and understand the manual.

Weather or not the Carrier is superior to the Lennox is mostly in the install. Carrier is more user friendly to the installer in regaurds to setting up the equipment.

I would opt for the two stage stat for the Lennox, but I would not worry about it if I had a Carrier. It is JMO though.

And as mentioned above, pull more wires than you need.

**koen** · 11-26-2005, 06:28 PM

Thanks alot for your reply's. Basically I think I will call the company back and have them come out again and install the 2 stage stat. As a consumer and paying a hefty price for this unit, I don't really think I should have to pay for the service call for them to come back out a third time, The stat yes but install no. I think this should have been attended to during the initial sales pitch and install. Either they dont know what they are doing or trying to take shortcuts or both. When the installer looked at installing the new stat (that came with the unit) he looked at mine and said "oh yours is better than this you don't have to change it." Well he should have said a 2 stage stat would be beneficial with this unit and I would have one put in at the same time. So I dont feel like I should have to pay for the install of the new stat. Am I way off for thinking this or is it my issue?? Im not really sure so any input from an installers point of view would be great
thanks!!

**Milk man** · 11-26-2005, 06:44 PM

Is it possible to pull new wire? Some times we are stuck with what we have.

Weather or not you should pay anymore is between you and the decision maker of that company, and nobody else. Was a new two stage stat quoted with your furnace?

**koen** · 11-26-2005, 07:01 PM

No the 2 stage stat was not quoted with the unit. It wasn't even mentioned. Thats what kind of annoys me. I think It should have been explained as part of making the system as beneficial as it can be. Why else would I have shelled out for something that isnt working at its full capacity.

Im just upset at the fact that I wasn't told in the first place. I mean they would have charged me anyway so why cut corners.

As for pulling more wire I don't see why not, its a newer home and it shouldnt be all that hard. I could probably run it myself and just have the installer connect it to the furnace.

**Milk man** · 11-26-2005, 07:24 PM

Your furnace is working at it's full capacity. Your furnace is sized to handle to coldest days in your area. The rest of the time it is oversized. That is just the way it used to be. Now with two stages your furnace will run on low fire most of the season. Timing on the high fire is acceptable. In other words, you stat wont call for high fire except for the colder days in the season. It will start with low fire on each call. If low fire won't keep up the stat will call for high heat. There will be a time difference between low and high fire waiting for "the second bulb to drop".

The quote is for an older style of electro mechanical stat and cheaper electronic stats. The high tech electronic stats control the heat to a much closer setpoint. Some with in a few tenths of a degree, but are expensive.

As far as it not being brought up by the salesman? He should have. He made a decision for you. You should have had the option to accept of decline the two stage stat.

**Toolpusher** · 11-26-2005, 07:57 PM

I think as far as paying for the install,
If you had the 2 stage stat the first time,
you probably would have paid and not have known it.

It would have been in the cost of the job,
So paying then or now, whats the difference ?

As you said above and the way I read your statements from this side of the screen, your more mad the rep didn't inform you of the options.

Talk to your rep, or the owner, In a calm manner.

**koen** · 11-26-2005, 08:56 PM

Sounds good!

thanks for the good advice!

**harl** · 01-24-2006, 11:50 AM

I have just had a lennox g61 mpv installed and it came with a Robertshaw c8425 2heat/2cool digital thermostat.I found out later that it seems to be up to the installer which thermostat to use.Although it seems to work quite well,I was thinking of replacing it with a more expensive model that might be able to utilize more features of this top of the line furnace.Although this furnace can be set to cut in with a diff of one degree,if the tolerance for the stat is + or - one degree this could be close to 2 degrees from set point until cut in.What kind of thermostat did you end up with and how was it?
Harl

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