HVAC Guru's

[dj_rice]

Hoping theres some HVAC guru's in here that can chime in.

Furnace is a Lennox Value Series furnace. Mid efficiency. Maybe 13-14 years old. Blower motor is a 5 stage motor.

Furnace shit the bed Friday. Gas would fire up and ignite but stay burning for a minute but the blower wouldn't turn on and turn off. Diagnostic lights pointed to "flame roll out switch, one light steady on, one light slow flash. Called a car forum recommended guy, and he came over, did his thing and determined it was faulty circuit board not sending a signal to the blower to turn on thus tripping the flame roll out switch. Original board was a 83M00, but I replaced with an upgraded circuit board from AMRE Supply. This one here

http://www.amresupply.com/part/12509494

He wired everything up, and now furnace is running again but a few things I noticed is,

#1 it seems like the blower is now running on a higher stage as than previously before as I noticed when the furnace is on, its alot louder and tons more airflow through the air ducts. Air flow wasn't as powerful and strong before.

#2 the furnace is turning on alot more frequently now, before maybe every 15-20 mins but now its like every 7-8 mins, and yes it is colder outside now -21 but that can't be it. Literally just now, furnace turned on, heated for 2-3 mins and shut off and 3 mins later, furnace turned back on and is heating again and just turned off now after 6 mins of heating. I have the thermostat set @ 20. And it it drops down 1 degree, furnace is kicked on.


I'm not sure if this is normal?Anyone chime in on tips before I call him and see if maybe its wired in-correctly? Any settings on the new board I might have to adjust?

[jeffh]

I think what you got is a 5 speed blower, not 5 stage. Trace the wires back from the blower motor to the board. They should be white black blue red yellow and maybe one more. Only work with the black and colored wires. They are essentially your speed control. Some will be in 'park'(dead wire holding spot) or on a heat hi, heat lo, or cool. Read the schematic on the back of the access door that pertain to the colored wires. Buddy likely engaged a 'faster' wire, like put a black or blue in place of a red or yellow. So pull one of the wires off its stake in park and change it with one on heat. A pic would help of your installed board, and even your installed faulty board if you got it..
Anyways this will slow down the air coming across the heat exchanger. Thus taking longer to remove the heat from it and spread it throughout your home and back to your thermostat. It will also be quieter and less draftier. Don't forget to change your filters, amre carries pleated one for around $7, so stock up

[dj_rice]

I think your right jeff. Because, now that the blower is working on a faster speed, my bedroom in the 2nd story, the air coming from out the vents is quite cooler and colder than before. So because the blower is working on faster setting, its cooling the air once it reaches the 2nd story if that makes any sense? Which would explain why the house is losing heat so fast and furnace is turning on more frequently, cause the air is getting cooler and dispersed.

I'll try reading a schematic and seeing I can attempt. I'll post up pics as well

Buddy hooked me up with great labour pricing and came on a Saturday to do the install so I won't bother him to come back to do something simple if I can fix it.

Reliance wanted $199 just to show up at my door for emergency call out.

[jeffh]

Well thanks. Based on the picture of the board provided by amre. It is the group of wires on the lower left hand side. Additionally, you must have a single-stage furnace as there is only one 'heat' connection. 'Fan' is like your summer switch. It should be close to the speed of your heat setting so its not as noisy. I assume you dont have ac, so the 'cool' stake is basically another 'park' in your case.

[dj_rice]

So then everything has to be wired up correctly?Cause he said it was it was wrong, the blower wouldn't turn on ?

Said my blower is a 5 speed, 2 for heating, 2 for cooling and 1 speed is the manual fan on setting.

Correct, I don't have A/C


He did say that he cleaned the air intake side of the blower so it could be functioning 100% now but I just had the furnace and ducts cleaned in Aug last year.

[dj_rice]

Heres a picture of how its wired up right now and there was some writing on the back of my panel I assume how it was wired in the beginning


http://i355.photobucket.com/albums/r470/djrice1234/IMAG0189_zpsbc257582.jpg
On the panel OEM config is
Black = Cool
Blue = Park
Brown = Heat
Yellow = Park

http://i355.photobucket.com/albums/r470/djrice1234/IMAG0188_zps97224c4f.jpg
Current config now is

Yellow= Cool
Black= Heat
Brown = Park
Blue = Park

Also noticed he might of forgot to put the lead going to the "FAN" as I have a 2nd story ventilation fan switch that should circulate the fan on low speed in summer, will have to check that

[jeffh]

Ya having one on cool is pointless, since you don't have ac. 'Cool' is usually for the fastest speed setting as it takes more air to flow through all the fins of the a-coil on an air conditioner and to prevent it from freezing up.
Make sure you have one wire at least on the 'fan' spot and one on the 'heat' spot. Play around with different wires/speeds until you get the one that you think is most comfortable. Initially, if you have 4-speeds(slow, medium, fast, super-fast), I would put medium or fast for 'heat' and consequently medium or fast for 'fan'.

[jeffh]

"So then everything has to be wired up correctly?Cause he said it was it was wrong, the blower wouldn't turn on ?"
-that's debateable. If you're furnace blower runs, but sounds like a freight train now, then I would not say it is wired up correctly, would you?

"Said my blower is a 5 speed, 2 for heating, 2 for cooling and 1 speed is the manual fan on setting."
Based on what you told me, based on the pic of the board and where you typed 'black, blue, brown, and yellow'... You have a 4-speed blower, 1 for heating, 1 for cooling, 1 for ventilation fan, and 1-2spots for park.

Also black is usually the fastest setting. Blue second fastest. Yellow is medium-slow. Not sure where brown is in the mix exactly, but likely medium or slow.

[dj_rice]

Originally posted by jeffh
"So then everything has to be wired up correctly?Cause he said it was it was wrong, the blower wouldn't turn on ?"
-that's debateable. If you're furnace blower runs, but sounds like a freight train now, then I would not say it is wired up correctly, would you?

"Said my blower is a 5 speed, 2 for heating, 2 for cooling and 1 speed is the manual fan on setting."
Based on what you told me, based on the pic of the board and where you typed 'black, blue, brown, and yellow'... You have a 4-speed blower, 1 for heating, 1 for cooling, 1 for ventilation fan, and 1-2spots for park.

Also black is usually the fastest setting. Blue second fastest. Yellow is medium-slow. Not sure where brown is in the mix exactly, but likely medium or slow.

Thanks for all your information and help, I'll start pulling wires and testing and see if it helps. Really appreciated. I did take apart the panel and look at the wiring diagram and seen something briefly on the motor about it having 5 speeds

Low, low-med, med, med-high and high speed. I'll have to re-double check

[Maxt]

What you should be measuring is the temperature rise across the furnace, and adjust the fan speed to get the proper temperature rise from the nameplate during heating operation. Once you have that adjusted, measure the discharge air temperature after the call for heat has ended, and reduce the fan off timing via the dip switches if the furnace is running on blowing room temp air.

[dj_rice]

Originally posted by Maxt
What you should be measuring is the temperature rise across the furnace, and adjust the fan speed to get the proper temperature rise from the nameplate during heating operation. Once you have that adjusted, measure the discharge air temperature after the call for heat has ended, and reduce the fan off timing via the dip switches if the furnace is running on blowing room temp air.


Sorry what......too technical. I'm not a HVAC guy, please explain

[Maxt]

On the name plate of the furnace, there will be a specification called temperature rise, basically the temperature difference between the incoming air and outgoing air while the furnace is burning gas. You might have to drill a couple of holes in the ductwork either side of it to put in a probe thermometer, the discharge thermometer should be in a horizontal run, not right above the heat exchanger. You need two reasonably fast acting thermometers to do this. Assuming the firing rate is set correctly, the furnace should be operating in the band on the furnace info tag, not enough temperature rise(air is cooler than should be ) will reduce the life of the furnace by corrosion, to hot of air to much temperature rise can lead to cracked air exchangers and limit trips.
Let it run for 10 minutes before taking the readings. I usually go for maximum airflow that will give 55 deg F temperature rise
Then turn thermostat off, watch the discharge air thermometer, when its down in the 90-95 deg F range, the fan should turn off. If its cooler than that, shorten the fan off time, there is a chart for the switch setting in seconds beside the dip switches on the board.

[dj_rice]

Originally posted by Maxt
On the name plate of the furnace, there will be a specification called temperature rise, basically the temperature difference between the incoming air and outgoing air while the furnace is burning gas. You might have to drill a couple of holes in the ductwork either side of it to put in a probe thermometer, the discharge thermometer should be in a horizontal run, not right above the heat exchanger. You need two reasonably fast acting thermometers to do this. Assuming the firing rate is set correctly, the furnace should be operating in the band on the furnace info tag, not enough temperature rise(air is cooler than should be ) will reduce the life of the furnace by corrosion, to hot of air to much temperature rise can lead to cracked air exchangers and limit trips.
Let it run for 10 minutes before taking the readings. I usually go for maximum airflow that will give 55 deg F temperature rise
Then turn thermostat off, watch the discharge air thermometer, when its down in the 90-95 deg F range, the fan should turn off. If its cooler than that, shorten the fan off time, there is a chart for the switch setting in seconds beside the dip switches on the board.


Damn so technical and I don't even have any thermometer. Can't I just revert back to how it was originally wired up and see if that works, wiring should still be the same, just a new circuit board installed and wrong lead put in wrong terminal?

[jeffh]

Yes just make do with what you got. You don't need a thermometer being a diy, and not a pro. The furnace is not going to blow up in your face, they have many sensors to protect itself, even on a mid efficient. It is only 4-5 wires, reasonably 2-3 wire, to interchange on the board to get the best desired effect. And your welcome, hope you get it figured soon. It'll give you a nice sense of accomplishment, and that you saved over $200.

[Maxt]

You can play around it with fan speed if you want,the setting of the temp rise is just the right way to set it to ensure the furnace operates properly within the manufacturers parameters and you get full life out your appliance and its controls.

[jeffh]

Agreed, a lennox mid efficient should last him a very long time. Ideally the heat exchanger will be the last part to fail.

[dj_rice]

Thanks for all the help guys.

I'll wait till the weather is warmer before I attempt anything. Don't want to do something and mess it up if thats even possible.

I might just leave it as it for now since its working and monitor my next heating bill and see if there is a massive spike then I'll know whats up

Also gotta check the wiring and see if the humidifier was wired up to the new board. I have two Humidifiers, one was a old Automatic one attached on top of the furnace not working and a brand new York one.