Lennox G43 Fan Speeds - Canadian TV, Computing and Home Theatre Forums

Mr_Rt · 2011-06-24, 10:15 AM

Wonder if someone might be able to help me out with a question about my Lennox g43 furnace fan. (The house is only 8 months old and the builder installed the G43).
Does this fan have the ability to circulate air at half speed and go to full speed when it's heating or cooling. I know its not a variable speed fan but am hoping there is a setting or jumper i don't know about. I know the Lennox in our previous house had this ability and it was an G40(me thinks) model. If you set the stat to Furnace Fan 'ON' it would circulate the air a lower speed, when it made a call for heat or cooling it would speed up.
2 Storey House, vaulted ceiling, 2300 sq ft
System in new house is
Lennox G43 92% eff (Meritt Series)
Lennox XC13 A/C (Lennox Closed Cube coil directly mounted to furnace)

I hope you can help me, with the fan only turning on when there is a call to heat or cool there is noticable difference in temps floor to floor. With the fan on it balances but I would like the fan to only run at half speed, vents closer to the system almost feel to have a draft on full tilt

txv · 2011-06-24, 03:59 PM

Here's the manual for your furnace: http://www.cozyparts.com/Lennox-Part...09-01-2007.pdf

In continuous fan mode, the blower runs at the heating speed.

To run the fan at the lowest speed, you'll have to get a relay added.

If money is no object and you want the fan to run at a very low speed-> http://www.emersonclimate.com/en-US/...e_ecotech.aspx

Mr_Rt · 2011-06-26, 04:03 PM

Thanks for the info. I have a service tech coming to look at some low air flow through some of the second level vents, i will certainly ask him if he can install the relay.

txv · 2011-06-26, 04:12 PM

FYI...

The relay gets connected to the heating blower terminal on the board instead of the blower.

From there, the normally closed terminal of the relay gets connected to the lowest speed, and the normally open terminal gets connected to the heating speed.

The relay is activated by a call for heat - W on the terminal strip.

dr dave · 2011-07-08, 01:36 PM

I ordered the recommended relay for this furnace but can I install it myself ? Assuming the relay is delivered without directions, perhaps someone could post the wiring instruction ?

txv · 2011-07-08, 08:09 PM

Based on the information I posted and the furnace's schematic, someone who's familiar with electrical should be able to do it.

You can search this board for more info - keywords ecotech motor.

Call a technician if you're not familiar with control wiring.

2011-06-24, 10:15 AM	#1
Mr_Rt Join Date: Feb 2005 Location: Edmonton Posts: 153	Lennox G43 Fan Speeds Wonder if someone might be able to help me out with a question about my Lennox g43 furnace fan. (The house is only 8 months old and the builder installed the G43). Does this fan have the ability to circulate air at half speed and go to full speed when it's heating or cooling. I know its not a variable speed fan but am hoping there is a setting or jumper i don't know about. I know the Lennox in our previous house had this ability and it was an G40(me thinks) model. If you set the stat to Furnace Fan 'ON' it would circulate the air a lower speed, when it made a call for heat or cooling it would speed up. 2 Storey House, vaulted ceiling, 2300 sq ft System in new house is Lennox G43 92% eff (Meritt Series) Lennox XC13 A/C (Lennox Closed Cube coil directly mounted to furnace) I hope you can help me, with the fan only turning on when there is a call to heat or cool there is noticable difference in temps floor to floor. With the fan on it balances but I would like the fan to only run at half speed, vents closer to the system almost feel to have a draft on full tilt

2011-06-24, 03:59 PM	#2
txv Veteran Join Date: Oct 2008 Location: Canada Posts: 1,740	Here's the manual for your furnace: http://www.cozyparts.com/Lennox-Part...09-01-2007.pdf In continuous fan mode, the blower runs at the heating speed. To run the fan at the lowest speed, you'll have to get a relay added. If money is no object and you want the fan to run at a very low speed-> http://www.emersonclimate.com/en-US/...e_ecotech.aspx __________________ WARNING: The HVAC information I provide is not based on field experience and DOES NOT constitute professional advice.

2011-06-26, 04:12 PM	#4
txv Veteran Join Date: Oct 2008 Location: Canada Posts: 1,740	FYI... The relay gets connected to the heating blower terminal on the board instead of the blower. From there, the normally closed terminal of the relay gets connected to the lowest speed, and the normally open terminal gets connected to the heating speed. The relay is activated by a call for heat - W on the terminal strip. __________________ WARNING: The HVAC information I provide is not based on field experience and DOES NOT constitute professional advice.

2011-07-08, 01:36 PM	#5
dr dave Join Date: Apr 2003 Location: Ancaster, ON Posts: 108	G43 blower relay I ordered the recommended relay for this furnace but can I install it myself ? Assuming the relay is delivered without directions, perhaps someone could post the wiring instruction ? __________________ Samsung 52A750; Onkyo 3008; Panny bd55; 9.1 Paradigm, APC conditioner

2011-07-08, 08:09 PM	#6
txv Veteran Join Date: Oct 2008 Location: Canada Posts: 1,740	Based on the information I posted and the furnace's schematic, someone who's familiar with electrical should be able to do it. You can search this board for more info - keywords ecotech motor. Call a technician if you're not familiar with control wiring. __________________ WARNING: The HVAC information I provide is not based on field experience and DOES NOT constitute professional advice.

2011-06-26, 04:03 PM	#3
Mr_Rt Join Date: Feb 2005 Location: Edmonton Posts: 153	Thanks for the info. I have a service tech coming to look at some low air flow through some of the second level vents, i will certainly ask him if he can install the relay.

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