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f1ford 01-20-2012 01:56 AM

Lennox Fan Speed
I have a Lennox Model G61MPV-06C-090-6 SN# 5905K15989 that is about 6 years old with a 2 stage burner and a variable speed blower motor. I recently added a General Aire Elite Steam Unit Model DS15P. The Thermostat is the new Honeywell Prestige model.
A NATE certified Tech wired the unit in yesterday (good man). Today I went down to check out the Steam Unit and found water running down the outside of the Evaporator housing, leaking out between the seams were the plenum meets the evaporator housing. I opened up the evaporator access panel and found the condensation is forming on the plenum around the steam nozzle (about 10 inches up).

The General Aire DS15P requires 1000 CFM of air to run at 70+% of capacity. The fan is running at about 500CPM (1350 at full speed for heating and cooling modes). The tech who wired the Humidifier and the thermostat told me there is no way he knows to increase the fan speed on this furnace for the Humidifier. He set the humidifier to 60% output. I lowered it to 50% and continue to have condensation, have now lowered it to 30% of capacity and the condensation is less but now humidity level is dropping in house.
I believe the problem is too little CFM.
Question: Is there a way to wire or set dip switches (or both) on the furnace to increase the fan speed when the humidifier calls for steam?

yuri 01-20-2012 05:48 AM

on continuos fan it runs at 450-500 cfm and the humidifier should not run then. needs to be wired with a 24 volt relay which gets energized off the W (heat) terminal and that relay closes contacts to energize the humidifier. I would use a Honeywell R8222 D or K type relay. When I get home later today or tomorrow I will check the dip switch settings for that unit as the low fire one may need increasing.

beenthere 01-20-2012 03:33 PM

Yuri. On that furnace. Isn't the Y2 terminal also the terminal used for Y when its only a single stage A/C?

If so, then couldn't the humidifier be connected to Y1 to run the blower at a higher speed/CFM for humidify calls when there is no heat call?

yuri 01-20-2012 03:43 PM

but what would happen when it does call for heat? you would have the heating relay kick in and its speed and also power the cooling relay at the same time and confuse the board. I am not familiar with that humidifier and its controls or recommendations. on the SLP they recommend another relay and especially with the communicating tstats. you are right about y1 and y2 and we snip the jumper when using a 2 stage ac vs 1 stage. I also don't like making special setups which can confuse the marginal techs later when they look at that board and not know why it was done that way.

beenthere 01-20-2012 03:49 PM

It could get confusing for some.

mot boards ignore a W call if they are already receiving a Y call, and vice cersa. Don't know about that board.

yuri 01-20-2012 04:00 PM

I would hate to try and then he would have no heat when Y was calling. I am going to look up his dip switch/cfm settings now.

yuri 01-20-2012 04:06 PM

You have approx 1365 cfm on low fire and 1500 on high fire so you should be OK.:thumbsup:

f1ford 01-22-2012 08:56 AM

I appreciate your help and will run it by the tech. will continue to follow your suggestions.

In the mean time I have ordered a 7522 17.5 inch steam nozzle which should help distribute the steam across the airflow.

The Steam unit is:

yuri 01-22-2012 09:00 AM

that is a very good idea.:thumbsup:

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