Lennox G43UF furnace Blower Speeds

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Old 10-26-08, 09:35 AM
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Lennox G43UF furnace Blower Speeds

Hello all

I have a g43uf furnace, I know it has a variable speed blower fan.

I just installed an HRV system and the furnace blower must operate all the time in order for the HRV to work.

I currently have the thermostat set to manual fan and the system deosn't need that much airflow to make things work.


I would like to run the furnace blower on the low speed all the time (thermostat in auto mode) and when heat or cooling air in the summer is called for by the thermostat it cycle up to normal speeds.

Can this be done?
 
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Old 10-26-08, 12:49 PM
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What is the make and model # of the HRV? What controls are you using or using the one built in the unit?
 
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Old 10-26-08, 07:55 PM
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Its a Venmar HRV 2600 with a separate venmar wall control model # 40415
 
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Old 10-26-08, 08:36 PM
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Originally Posted by markymark View Post
I have a g43uf furnace, I know it has a variable speed blower fan.
Sorry to say, this furnace is a basic single stage furnace with a standard Multi-speed(fixed) blower motor.

I just installed an HRV system and the furnace blower must operate all the time in order for the HRV to work.
I had a very hard time finding a manual on this, and the one I found shows nothing if it should or how to wire it to the furnace's control board to turn on the blower when the HRV is running.


I would like to run the furnace blower on the low speed all the time (thermostat in auto mode) and when heat or cooling air in the summer is called for by the thermostat it cycle up to normal speeds.

Can this be done?
Your furnace when you run the fan in "ON" mode, the blower runs the heating speed (Most of the time is' lower than cooling speed) and if there call for cooling, the blower will jump to a higher speed.

Not sure where you are out of, but in the summer you really don't need to run this, unless you never open your windows all summer? Running the fan On all time in the summer adds more humidity into the air.
 
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Old 10-27-08, 06:57 AM
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This is what I have been able to find that will help if it will work

C&P From another site

I mentioned this to one of the HVAC engineers at work and ended up getting a fan relay installed. The relay cost $10 (white rodgers 90-293Q) and connects to the heat lead ("W") on the furnce controller and the common terminal is wired to the "heat" terminal on the controller. The med-low blower lead is connected to the normally open contact and the low speed is connected to the normally closed contact. In this manner when there is a call for heat ("W" terminal energized) the med-low blower speed is selected but if there is no call for heat and there is a call for fan ("G" lead energised on it's own) then the low speed on the blower is selected. The net result is that I can run my fan full-time and I'm only using the 1/10 HP mode of the blower motor not the 1/8HP and the fan is quieter.
 
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Old 10-27-08, 07:13 AM
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Not sure how that can work...

-If the W wire goes to the relay, the common wire going to the heat control on the board... The common side is power used up.. it won't fire up the furnace.

-Sounds like the blower heating speed is going to start right away when call for heat, no time delay.

-The motor is going to burn up if the low speed is running, then G (Fan on) is called for, both low and fan on speed is running at the same time..


You'll need a couple relays to get this to work right. I can sit down when I have a chance and draw it out to see if we can make it work.

Do you have the install manual on your HRV, does it show any wire that needs to go to G on the furnace?
 
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Old 10-27-08, 07:25 AM
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The connections on the HRV control are Y R G B and show no interconnect to the furnace

The wall control is model venmar 40415
 
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Old 10-27-08, 08:04 AM
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Old 10-27-08, 07:36 PM
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Originally Posted by markymark View Post
The connections on the HRV control are Y R G B and show no interconnect to the furnace
Are you able to scan or take a photo of your diagram that you are seeing?
 
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Old 10-29-08, 04:02 PM
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Pretty simple control Y R G B and the wires from the unit are Yellow to Y Red to R Green to G and Black to B. I was wondering if I used another control from Venmar that has an FF term to control the furnace fan???


http://www.kentinternational.ca/broc...r_Controls.pdf

I am going to call Venmar tomorrow
 
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Old 10-29-08, 07:30 PM
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Originally Posted by markymark View Post
if I used another control from Venmar that has an FF term to control the furnace fan???
I would do that if I were you.. By the time you get all these relays to make it work it may cost you as much as a new control that you can wire the fan to.
 
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Old 11-18-08, 01:04 PM
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Hey markymark,

Were you able to get the furnace fan working with HRV?
I have the same wall control and want to connect the furnace fan as well.

Thanks
 
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Old 12-16-08, 05:47 PM
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Question

Did anyone manage to figure this issue out? I have the hepa 3100 HRV with the 40415 control and was wondering if there is a contol to allow interconnect?
 
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Old 05-22-09, 04:41 PM
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I am also looking for info on this
Wooly
 
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Old 04-25-10, 11:41 PM
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I have the exact same equipment as you do but i haven't installed the hrv 2600 yet or the vision pro iaq yet but will do shortly.

Did you ever find out a way to get the 2 controls to communicate after all??

Also can that visionpro iaq variably control the furnace blower fan ecm with what i say - so when it calls for hrv ventalion, turn on venmar 2600 hrv AND turn on furnace blower fan to say certain cfm???????? also will the visionpro iaq still control heat and cool while it automatically turns on the HRV.

So for instance, say the current temp in house is ok.
Now it's time for ventilation so the visiopro starts the HRV and my present furnace blower fan speed.
But now the new fresh outside air drops the temp below set point, so will the visionpro turn on the gas heat in the furnace and increase blower speed all the while maintaining the ventalation cycle?

i have a new Goodman GMV950704 furnace and new ac

Thanks
 
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