Best way to set up Lennox G61V 2 stage furnace with one stage t-stat? - Canadian TV, Computing and Home Theatre Forums

kies1 · 2007-09-18, 04:58 PM

Hi,
What is the best way to set up this furnace. Using a one stage t-stat and letting the furnace decide when to go to second stage or installing a proper 2 stage t-stat and allowing the t-stat to determine this. House is 1285 square foot semi with a finished basement. I have been told you are not taking full advantage of the 2 stage furnace using a 1 stage t-stat. The contractor who is installing the furnace says with the size of my house it is best to set up the furnace on an 8 minute time delay and if the t-stat has not been satisfied it will kick the furnace into the second stage after 8 minutes. Any help or recommendations would be appreciated. They have told me they will hook it up either way. Thanks in advance. Furnace and a/c being installed Oct. 1st.

Dog Byte · 2007-09-18, 09:20 PM

Using a 2-stage thermostat means faster warmups after a night setback. If there's a lot of heating to do then both stages fire right away. Another approach is to use outside air temperature to decide 1 stage or 2 but that's probably a different controller.

If I had a 2-stage furnace then I'd have a 2-stage thermostat.

kies1 · 2007-09-18, 10:09 PM

Thank you for the reply, that is exactly what I was thinking. Any other recommendations or experaince with this?

Dog Byte · 2007-09-18, 10:44 PM

Depending on the furnance and burners the controller can be set up to have a primary and secondary burner or to alternate burners (so they wear out together).

On a 2-stage thermostat you might be able to set the delta or difference between the 2 setpoints. For example, if the temperature is set to 20C, then stage 2 might be 20 - 2C (18C). (2C is the delta.) It's just a fine tuning exercise once you're familiar with your system.

It's worth reading the furnace installation manual just to see what other programable options you have.

I put my boiler on a plug so when the power goes out I just plug into my generator. Very handy when the power is out for 24 hours.

otown47 · 2007-09-19, 07:29 AM

I have a 2 stage furnace and tried a 2 stage thermostat when it was first installed but found it too complicated to use as it made "decisions" automatically that I didn't want made and which couldn't be programmed around....so I went back to my original thermostat and all is fine. The 2 stage thermostat did have anticipatory settings but I found I didn't really need that (apparently you do if you have a boiler). There are toggle switches in the 2 stage furnace that will control when the second stage kicks in ( and will up the fan speed as well).

kies1 · 2007-09-19, 06:21 PM

Dog Byte,
From my understanding with the 2 stage t-stat it does exactly what you say. You can set up 2nd stage to fire when there is a differance of 1-3 degrees. Also you can have the humidifier hooked up as well and control the humidity in the house through the 2 stage t-stat as well. I think I will try this set up and see how it works. I can fiddle with it until i get it right i guess. Thanks

TKG26 · 2007-09-19, 11:55 PM

Just to clarify two stage furnaces have to firing rates

For example
100,000btu is high fire(second stage)Higher fan speed
75,000 is low fire(first stage)Lower fan speed

The gas vavle is running at 2 different manifold pressures usually:
1.5"wc for first stage
3.5"wc for second stage
All burners fire at all times.

I prefure the stingle stage stats and let the furnace technology do the staging. I'm not sure how lennox does its staging but if its similar to the way carrier and ammana do it, the furnace is constantly calculating cycle durations and frequency, it detects when the load in the house increases. I doubt that it uses the cheaper "timed" 2 stage that some use where dip swtichs are set for 5,10,15minutes of low fire. In those cases im all for the 2 stage stats.

The thing is furnaces are sized for the worst possible day of the year. Wich we rarely get for any length of time, you will find as Lennox points out that you will run low fire most of the time.

kies1 · 2007-09-20, 11:26 AM

Thanks for all the replys,
Signed the contract lastnight. What they are installing for a t-stat is a honey well vision pro IAQ thermostat. It will run the furnace, humidifier and air cleaner. This seemed to be the best option as it only needs a 3 wire hook-up to the display and the control unit is then hooked up to all the devices( furnace, humidifier etc). This way i can control humidity levels, heat and a/c at the touch of one unit. Was pretty happy with the final outcome. Thanks again for all the advise.

TKG26 · 2007-09-20, 04:20 PM

Kool sounds similar to the infinity. Infinity used ABCD wires to all components

cyclo · 2007-09-22, 01:33 AM

I have a Lennox 2 stage with a 1 stage electronic thermostat (total of five wires if memory serves me right, 3 for the furnace and 2 for the AC). It was going to be difficult to replace the thermostat wiring so I manually programmed the dip switches in the Lennox's motherboard to enable this "pseudo" 2 stage operation.

kies, you are right, with this "pseudo" 2 stage operation, the furnace operates in stage 1 for a couple of minutes and goes to stage 2 if the target temp is not yet reached (forgot the exact time). It also reverts back to stage 1 for a few minutes before shutting off after the target temps have been reached.

I also replaced my original electronic thermostat as I noticed it was "hunting" (turning the furnace on and off) after the target was reached. I got one that featured a programmable "swing" which prevents the furnace being turned on and off sometimes in a matter of seconds.

kies1 · 2007-09-22, 09:28 AM

That is why i decided to go with with this vision pro t-stat. Display is hooked up to where your original t-stat is. Only needs 3 wires. Then the control box/module is installed in your furnace room or directly on the unit. Then from this module all componants are directly hooked up. Furnace, a/c and humidifier. The diisplay then sends the information to this box which in then controls all functions of the two stage furnace. It will allow me to humidify, de-humidify and control the furnace like a 2-stage furnace was desingned. I as well was going to go with my existing 1 stage t-stat and program the dip switches due to wiring issues. With this vision pro assemmbly all this has been rectified and I can use the new hvac system to it's full potential.

Bulldog67 · 2007-11-14, 11:10 PM

Can I ask which vision pro t stat you are using? I have a Trane xv90 high efficiency furnace and would like to use a 2 stage t-stat as well. This sounds like it would be a good option.

JohnnyG · 2007-11-15, 11:12 AM

I believe our 2-stage Lennox furnace has a jumper setting on it's controller board to indicate whether you are using a single stage or 2-stage t-stat.

Which reminds me...when it was installed last Spring, we had a single stage t-stat that has since been replaced and I never got around to wiring it all properly.

2007-09-18, 04:58 PM	#1
kies1 Join Date: Mar 2006 Posts: 22	Best way to set up Lennox G61V 2 stage furnace with one stage t-stat? Hi, What is the best way to set up this furnace. Using a one stage t-stat and letting the furnace decide when to go to second stage or installing a proper 2 stage t-stat and allowing the t-stat to determine this. House is 1285 square foot semi with a finished basement. I have been told you are not taking full advantage of the 2 stage furnace using a 1 stage t-stat. The contractor who is installing the furnace says with the size of my house it is best to set up the furnace on an 8 minute time delay and if the t-stat has not been satisfied it will kick the furnace into the second stage after 8 minutes. Any help or recommendations would be appreciated. They have told me they will hook it up either way. Thanks in advance. Furnace and a/c being installed Oct. 1st.

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2007-09-18, 09:20 PM	#2
Dog Byte Join Date: Apr 2004 Location: Langley, BC Posts: 863	Using a 2-stage thermostat means faster warmups after a night setback. If there's a lot of heating to do then both stages fire right away. Another approach is to use outside air temperature to decide 1 stage or 2 but that's probably a different controller. If I had a 2-stage furnace then I'd have a 2-stage thermostat.

2007-09-18, 10:09 PM	#3
kies1 Join Date: Mar 2006 Posts: 22	Thank you for the reply, that is exactly what I was thinking. Any other recommendations or experaince with this?

2007-09-18, 10:44 PM	#4
Dog Byte Join Date: Apr 2004 Location: Langley, BC Posts: 863	Depending on the furnance and burners the controller can be set up to have a primary and secondary burner or to alternate burners (so they wear out together). On a 2-stage thermostat you might be able to set the delta or difference between the 2 setpoints. For example, if the temperature is set to 20C, then stage 2 might be 20 - 2C (18C). (2C is the delta.) It's just a fine tuning exercise once you're familiar with your system. It's worth reading the furnace installation manual just to see what other programable options you have. I put my boiler on a plug so when the power goes out I just plug into my generator. Very handy when the power is out for 24 hours.

2007-09-19, 07:29 AM	#5
otown47 Veteran Join Date: Jul 2002 Location: Ottawa, Rogers Posts: 3,902	I have a 2 stage furnace and tried a 2 stage thermostat when it was first installed but found it too complicated to use as it made "decisions" automatically that I didn't want made and which couldn't be programmed around....so I went back to my original thermostat and all is fine. The 2 stage thermostat did have anticipatory settings but I found I didn't really need that (apparently you do if you have a boiler). There are toggle switches in the 2 stage furnace that will control when the second stage kicks in ( and will up the fan speed as well).

2007-09-19, 06:21 PM	#6
kies1 Join Date: Mar 2006 Posts: 22	Dog Byte, From my understanding with the 2 stage t-stat it does exactly what you say. You can set up 2nd stage to fire when there is a differance of 1-3 degrees. Also you can have the humidifier hooked up as well and control the humidity in the house through the 2 stage t-stat as well. I think I will try this set up and see how it works. I can fiddle with it until i get it right i guess. Thanks

2007-09-19, 11:55 PM	#7
TKG26 Veteran Join Date: May 2007 Location: OTTAWA Posts: 2,891	Just to clarify two stage furnaces have to firing rates For example 100,000btu is high fire(second stage)Higher fan speed 75,000 is low fire(first stage)Lower fan speed The gas vavle is running at 2 different manifold pressures usually: 1.5"wc for first stage 3.5"wc for second stage All burners fire at all times. I prefure the stingle stage stats and let the furnace technology do the staging. I'm not sure how lennox does its staging but if its similar to the way carrier and ammana do it, the furnace is constantly calculating cycle durations and frequency, it detects when the load in the house increases. I doubt that it uses the cheaper "timed" 2 stage that some use where dip swtichs are set for 5,10,15minutes of low fire. In those cases im all for the 2 stage stats. The thing is furnaces are sized for the worst possible day of the year. Wich we rarely get for any length of time, you will find as Lennox points out that you will run low fire most of the time.

2007-09-20, 11:26 AM	#8
kies1 Join Date: Mar 2006 Posts: 22	Thanks for all the replys, Signed the contract lastnight. What they are installing for a t-stat is a honey well vision pro IAQ thermostat. It will run the furnace, humidifier and air cleaner. This seemed to be the best option as it only needs a 3 wire hook-up to the display and the control unit is then hooked up to all the devices( furnace, humidifier etc). This way i can control humidity levels, heat and a/c at the touch of one unit. Was pretty happy with the final outcome. Thanks again for all the advise.

2007-09-20, 04:20 PM	#9
TKG26 Veteran Join Date: May 2007 Location: OTTAWA Posts: 2,891	Kool sounds similar to the infinity. Infinity used ABCD wires to all components

2007-09-22, 01:33 AM	#10
cyclo Join Date: Dec 2005 Location: Toronto Posts: 662	I have a Lennox 2 stage with a 1 stage electronic thermostat (total of five wires if memory serves me right, 3 for the furnace and 2 for the AC). It was going to be difficult to replace the thermostat wiring so I manually programmed the dip switches in the Lennox's motherboard to enable this "pseudo" 2 stage operation. kies, you are right, with this "pseudo" 2 stage operation, the furnace operates in stage 1 for a couple of minutes and goes to stage 2 if the target temp is not yet reached (forgot the exact time). It also reverts back to stage 1 for a few minutes before shutting off after the target temps have been reached. I also replaced my original electronic thermostat as I noticed it was "hunting" (turning the furnace on and off) after the target was reached. I got one that featured a programmable "swing" which prevents the furnace being turned on and off sometimes in a matter of seconds.

2007-09-22, 09:28 AM	#11
kies1 Join Date: Mar 2006 Posts: 22	That is why i decided to go with with this vision pro t-stat. Display is hooked up to where your original t-stat is. Only needs 3 wires. Then the control box/module is installed in your furnace room or directly on the unit. Then from this module all componants are directly hooked up. Furnace, a/c and humidifier. The diisplay then sends the information to this box which in then controls all functions of the two stage furnace. It will allow me to humidify, de-humidify and control the furnace like a 2-stage furnace was desingned. I as well was going to go with my existing 1 stage t-stat and program the dip switches due to wiring issues. With this vision pro assemmbly all this has been rectified and I can use the new hvac system to it's full potential.

2007-11-14, 11:10 PM	#12
Bulldog67 Join Date: Jan 2007 Posts: 1	Can I ask which vision pro t stat you are using? I have a Trane xv90 high efficiency furnace and would like to use a 2 stage t-stat as well. This sounds like it would be a good option.

2007-11-15, 11:12 AM	#13
JohnnyG Veteran Join Date: Dec 2001 Location: North York, Ontario Posts: 10,407	I believe our 2-stage Lennox furnace has a jumper setting on it's controller board to indicate whether you are using a single stage or 2-stage t-stat. Which reminds me...when it was installed last Spring, we had a single stage t-stat that has since been replaced and I never got around to wiring it all properly.