furance damper issues

[lennoxissues]

Hi everyone, I am new here. I have a question that I am hoping someone's expertise may be able to help out with.

I have a Lennox Whipserheat gas furnace. When the thermostat calls for heat, the damper only opens about a half inch or so, and then just makes a clicking noise. If i slowly and carefully help the damper open and hold it until the furnace lights and the fan comes on, I can let it go and it will run normally until the thermostat setpoint is achieved. The damper will then close and the furnace will shut off like its supposed to.

I initially read that it is either the damper motor itself or a piece of plastic that conects the motor to the damper that broke, which backed my first assumptions of what was wrong. But then i came across some post where it may be a sensor, thermostat or possibly not enough power going to the motor, things of that nature. I am great with mechanical things, and bad with electrical things so I am hoping that if there is no quick easy fix it is something with the motor or damper and not something that requires electrical trouble shooting.

This seems like a fairly common issue with the lennox whisperheat furnaces so I was hoping that someone else may have been through this and could share some tips or information.

I do have a video showing this problem, but it is about 45MB whic is too large to upload. I have a way of getting this to anyone who would like to have a look, I just need an email address.

Thanks in advance for any help anyone may have on this problem.

[HayZee518]

damper

from the sound you heard as the motor was revolving, the click-click-click would indicate slipping of some sort. maybe its a friction disk that connects to the damper, could also be a set of nylon gears in the reduction unit that are slipping if the damper flapper is getting stuck in the exhaust ductwork.

[HayZee518]

furnace

if it was a sensor then me thinks nothing would work, but you say if you help the damper to open, you have fire. check the alignment of the damper within the pipe. then if that fails go for changing the motor or coupling to the damper.

[dfitz3390]

i would suggest calling a repair service. it sounds like you have a flue damper with an end switch in it that makes sure it is completely open before allowing the burner to fire.
is the video you mentioned posted anywhere ?

[lennoxissues]

I don't have the video posted anywhere, but I have a file sharing site that I can put it on and email you a download link. Let me know if you would like to give that a try. Thanks for the response.

[dfitz3390]

i sent you a private message containing the address.

[lennoxissues]

Sorry about the late reply. I have been looking into a new furnace because it was on the to-do list anyway. Unfortunatley this raises a lot more questions and problems. Looks like this will be one expensive summer, especially considering that just a few weeks ago, the hot water tank had to be replaced.. Good times......lol

[hawkins111]

new furnace

Could you give us some idea what was wrong with the furnace that necessitated a new unit? Also, what type of water heater do you have?

Thanks,

Tom

[lennoxissues]

The damper motor, or linkage seems to be broken. The furnace is about 20 years old anyway. We were planing to replace it this summer with a high efficiency model anyway, so we figure there really is no point in dumping time and money into the old one to go ahead and replace it a few months later anyway.

The water tank is gas, 40 gallon, 40,000 btuh. I have been told that I should have replaced the tank with an electric one, so that I could have just abandoned the existing venting that the old furnace and water tank share and not worry about the venting being possibly oversized for the water tank once the furnace is removed. I think this would have been just trading one possible problem for another. There is no spare capacity on the current electrical panel, so I assume I would have had to have an electrician come in and replace that with a new one.

[dfitz3390]

the flue damper shouldnt be that big of a deal. i still didnt get link so i cant help you there and the model would be helpful too.

Dan

[HayZee518]

electric panel

if you don't already have them, you can replace four of the single pole breakers with two twin breakers which will open up a two pole slot in your panelbox.

[lennoxissues]

Well, I am not too sure about what I am going to do. I think I may just go ahead with the furnace install as planed, and deal with the water tank after if needed. Everyone I talk to at work seems to think differently about the potential venting issue. Some say that it is very rare that this is ever an issue, others seem to think it is more common.

The way I see it, all spring/summer when the furnace isn't in heating mode, or is off all together, the hot water tank is just fine and there are no flue gas issues. So, if the old furnace is removed and its vent is capped, it should be fine. Maybe I am missing something, but it seems to me if the vent up to the roof is too big to properly vent just the hot water tank, I would have issues when the furnace is off, and just the hot water tank is running.

I did check with someone at work in case an electric hot water tank is what I need, and he thinks that my panel should be fine if I do what HayZee518 suggested.

[hawkins111]

options for water heater

We really need to know which model and size water heater you have as well as how big the chimney is. It would be nice to know who high the chimney cap is above the highest part of your roof. Lennox shows in their drawings a water heater is OK to tee into the flue for the heater. Most of the Lennox gas units have a 6 inch flue pipe, where a lot of the gas water heaters are 3 or 4 inch. It depends on where you live and how much your electricity costs as to the benefit of an electric water heater. Just off the top of my head I would think gas would be a cheaper option. Tom

[lennoxissues]

The new water tank is a Bradford White 40 Gallon, 40,000 btuh. The vent from it is 4". The vent from the old furnace is 5.5" and they tie into a 6" vent that goes to the roof. I am unsure of how far the vent sticks up from the roof, but the run to the roof is about 22 feet. Gas is cheaper, but for me eliminating this potential over-sized vent issue would be worth the slightly higher cost of operation.

[hawkins111]

water heater vent

Does your new water heater have a vent damper? It should be sitting right on top of the water heater. Its job is to close when the heater is off. This cuts down on the stand by loss (draft going up the stack when off, cooling the water). If the vent going up is 6 inches you should not have any problem with the venting, even with just the water heater venting.Tom