Please help - short video to listen to...

[mypov]

This is not a garage furnace, but we just bought this house, and are stretched pretty thin until my next raise with my job...Don't really have money to call furnace Repair Tech. Please help if you have the time. There is a short video I've posted on youtube to listen to the symptoms ... This is a lennox furnace, natural gas, made in 93, mid efficiency...

Video is located here:

The following description is on youtube video post as well:

Something is wrong with my furnace ... Great people of Garage Journal, please help...
Often times it will make that banging/clicking at the beginning of the video when it first starts, sometimes it will make that banging, continuously for a few moments, and will accelerate as the furnaces appears to be lighting (don't know if that is correct terminology)

 

[Boyd]

What's the model # of the furnace? It should be on a data sticker on the door you pulled to make the video.

 

[mypov]

Does anyone know where to start with a Problem like this? I wonder if there are forms for heating ???

Thanks for any hints or information you can provide.

 

[mypov]

I am not sure of the model number right now. I'm at work but I can post that information tonight when I get home.

 

[Boyd]

It sounds like a bad blower relay. But if you have a model # it will help with the diagnosis.

 

[Falcon67]

Does anyone know where to start with a Problem like this? I wonder if there are forms for heating ???

Thanks for any hints or information you can provide.

Only one I know is HVAC Talk and they are NOT DIY. They will kick you off for posting a DIY question.

Did you not get any sort of home warranty as a part of the purchase? That's pretty standard these days.

 

[oldgoaly]

ok from the video it sounds like a vent motor rattling, but can not see the vent or if it has one. That could change sound as the heat builds up.
I had a couple of cheaper White / Rodgers electronic thermostats go bad and cause the gas valve to ring like an alarm clock, but these were on older standing pilots furnaces. 1st one took me a little bit, change the gas valve 1st, second one went right to the stat. Something goes bad in the t-stat that causes the switching transistor to oscillate, not supposed to do that. If it was to do that on newer furnace could cause a funky sound from the control board relay.

 

[dairdvl]

mypov
being a Hvac tech its hard to tell by your video w/o standing there seeing the sequence of operation when it starts doing this. from the vid it looks like a standard nat draft furnace w/ no inducer motor. few questions: does it have a standing pilot? does it start the noise immediately when there is a call for heat or when it is just sitting there?

 

[DenisG]

Has the furnace ever worked correctly for you? Was the house unoccupied for some time before you moved in (purchased a foreclosed house)? Maybe some condensation in the gas line?

 

[mypov]

mypov
being a Hvac tech its hard to tell by your video w/o standing there seeing the sequence of operation when it starts doing this. from the vid it looks like a standard nat draft furnace w/ no inducer motor. few questions: does it have a standing pilot? does it start the noise immediately when there is a call for heat or when it is just sitting there?

I don't think this has a standing pilot - I cannot see one anyway. When the ignition process starts then a pilot comes on before the (what look like to me) flames ignite for the heat exchangers. Makes this noise when heat is called for - and usually goes away once furnace is running...

Has the furnace ever worked correctly for you? Was the house unoccupied for some time before you moved in (purchased a foreclosed house)? Maybe some condensation in the gas line?

We moved in only on Friday, were making short visits since the 14'th, but it always seemed warm. Has made this noise intermittently (sometimes furnace works flawlessly) since we moved in on Last Friday.

What's the model # of the furnace? It should be on a data sticker on the door you pulled to make the video.

model number:G20Q3/4E-100H-C2

New development though. Came home tonight at 8:00PM to a house sitting at 60 Degrees F. Should be at 70. No heat now. Might be time to call professional. Sorry for my ignorance in describing things. I feel like a customer telling me about a noise they have in their front end. Amazing how knowledge doesn't necessarily translate to other trades.

 

[mypov]

Yeah, no pros available. Awesome...Just looked at some more youtube vids and it appears as though mine is not igniting properly. When thermostat calls for heat, I can see that the pilot comes on, and hear the igniter clicking away (it's a nice clicking sound, not the sound in the video) but no flame - thus no heat. Going to try to clean igniter and flame sensor and see if that fixes the problem.

 

[Boyd]

mypov - Inside the furnace, can you locate the wiring from the thermostat?

 

[mypov]

I think so...I can definitely see where the come down, but they look to be in order, and the furnace acts upon adjustment of the thermostat?

Okay, so after cleaning what I think is the igniter, and the flame sensor, it seems the ignition process is working. As when I turn on the thermostat, furnace receives call for heat, allows gas to flow, and electric ignition lights pilot light - but that is where it ends. The large flames are not light to heat up the heat exchangers...Tested for voltage, found 25 volts, but not too sure where to go from here.
Back to google.

 

[Boyd]

Where did you test for voltage?

 

[Boyd]

Can you see or hear the air damper open before the igniter tries to fire?

 

[mypov]

i can see the damper open.
Just had a "pro" come in and tell me the gas valve is "pooched" ...I'm a little skeptical because he had one pupil bigger then the other, almost insisted that i buy a new furnace, saying i'll be breathing in unburnt fumes. There is no denying that carbon monoxide can be a problem. He offered to sell me a new gas valve for 500 dollars, but said I was throwing good money on bad.
I think that I'll just replace the gas valve myself and get a gas/appliance inspector in to assess the situation. I asked if the guy was certified, he said he's a journeymen sheet metal worker - not an HVAC guy. Oh yeah, and he said he could install the furnace tomorrow.

 

[mypov]

it could very well be the gas valve... ugh, need a life manual at this point.

 

[jdfinch22]

sounds to me that the gas valve sylinoide is going bad three things should happen when the t-stat calls for heat the igniter kicks the gas valve kicks and then a flame sensor that shuts off the ignitor on presence of flame or turns off gas valve on no flame the blower system is seperet except for the high kimit witch would lock out the burner from running

 

[Boyd]

i can see the damper open.
Just had a "pro" come in and tell me the gas valve is "pooched" ...I'm a little skeptical because he had one pupil bigger then the other, almost insisted that i buy a new furnace, saying i'll be breathing in unburnt fumes. There is no denying that carbon monoxide can be a problem. He offered to sell me a new gas valve for 500 dollars, but said I was throwing good money on bad.
I think that I'll just replace the gas valve myself and get a gas/appliance inspector in to assess the situation. I asked if the guy was certified, he said he's a journeymen sheet metal worker - not an HVAC guy. Oh yeah, and he said he could install the furnace tomorrow.

Don't let the "pro" scare you. Did he do a CO test at all?

Also, a new gas valve can likely be bought for less than $100 and it's very easy to install. Just make sure you have the gas and electricity shut off. There should be a gas shut off on the gas line just before the unit. The hardest part about the install will be finding a parts supplier that will sell you the part.

 

[DenisG]

i can see the damper open.
Just had a "pro" come in and tell me the gas valve is "pooched" ...I'm a little skeptical because he had one pupil bigger then the other, almost insisted that i buy a new furnace, saying i'll be breathing in unburnt fumes. There is no denying that carbon monoxide can be a problem. He offered to sell me a new gas valve for 500 dollars, but said I was throwing good money on bad.
I think that I'll just replace the gas valve myself and get a gas/appliance inspector in to assess the situation. I asked if the guy was certified, he said he's a journeymen sheet metal worker - not an HVAC guy. Oh yeah, and he said he could install the furnace tomorrow.

Did you find the Lennox G20 service manual online? It may help, but it may also narrow things to temporarily jumper safety switches mentioned in the service manual section on "Operation Sequence". I'll bet that one of the safety switches is intermittent (flakey) and is causing the gas solenoid valve to click on an off. In any case, as a general rule, I usually make it a point to check out the cheapest parts that might be involved in proper operation. (I'll bet the "pro" didn't test any of those switches.)

 

[oldgoaly]

Sounds iffy to me, your valve could be bad but... it is lighting the pilot so the pilot side of gas vale is working, is there 24 volts at the gas valve after pilot is lit? if not there is a limit switch or safety switch holding the main burner off. it will be in series on your wiring diagram. If this is the cheaper lennox is it a rebranded Armstrong? They owned them around that time.

 

[dogdog]

did you try to follow some of the troubleshooting procedure from your manual?
http://www.lennox.com/pdfs/installation_maintenance/Lennox_G20_IOM.pdf

Not sure if those uses thermocouples or if that flame sensor is replacing that.... but page 20 / 21 tells you how to check those the sensor for the proper microAmps when pilots are lit. At least on my gas units (not G20) it's manual pilot but if the thermocouple is bad it won't lite or maybe a weak signal causing the gas valve to cycles...... there is another posting somewhere tells you to how to check if gas is flowing .... but you have to use common senses and google... the point is to isolate the components. That is usually how I DIY my oil and gas burners. but this limited to a Burnham and Carloine. Couldn't offer you a pro answer. but that $500 for gas valve ...... is crazy highway robbery .

 

[mypov]

I don't know why I find it easier to read a manual and completely disassemble an engine, but when reading about these voltage tests and jumpers, safety switches, igniters and all that I get confused...Anyway, after showing the sketchy "pro" out of my house not really accepting his diagnosis - I ended up getting the furnace running. I checked for voltage at the screws for Main Valve and Pilot Valve - this was at one time 25 volts, but then I couldn't get it to show again, so I am not sure if there was something wrong with my DVMM - maybe it is not able to deal reliably in low voltage, but I think it should work for this purpose.

Anyway, I followed connections throughout furnace, and thought that there may have been a problem getting voltage to main gas valve so it would open and allow fuelling for heat exchange ignition. So, after fiddling with all connectors, it fired - and worked all night.

The crazy thing about this guy the "sketchy pro" is he said all the right things that would have convinced, I'm sure, a lot of people to go for the new furnace. He started by saying he would charge me a 200 dollar service call, 500 dollars for the gas valve, and another 100 dollars to install the valve - OR you could buy a new furnace from me and I'll wave the service call fee, and you will get a NEW furnace. He continues by saying, I'll be here tomorrow to install the furnace...Man, even knowing how unlikely it was that my furnace was completely trashed, I had the tiniest inkling to accept his offering. I also informed this guy of the tests he failed to run while at my house, and that after running them, and checking all the connections I was able to get the furnace to run - he then said I didn't have to pay him (One good thing about this guy, he could have demanded the fee)...

Just posting this so others are aware, people are largely out there to screw you! Be careful, do your research, and if something feels "off" it likely is - if someone is trying to scare you into buying a new appliance, just wait a little while and see if something else pans out - for a lesser or more reliable amount. Luckily this had a happy ending and Today, I was able to call a proven company and have one of their workers inspect my furnace, diagnose the igniter - furnace is purring away.

A very large thank-you to you all on here. I more than appreciate your input and pointers for diagnosing my furnace. I hope I can reciprocate someday.

 

[DenisG]

Glad that you got it going. Intermittent problem are often the hardest to diagnose and it sounds like you found it in bad wiring. It's easy to get overwhelmed by the schematics, but once you realize the reason why the inputs to the control board are there and how the sensors function (sometimes as simple on/off switches), things become more sensible.

 

[Mike007]

The crazy thing about this guy the "sketchy pro".

You didn't hire a pro, you hired a tinknocker working on the side, no?:

Just had a "pro" come in and tell me the gas valve is "pooched" I asked if the guy was certified, he said he's a journeymen sheet metal worker - not an HVAC guy.

Maybe next time you should call a reputable company instead?

 

[dogdog]

LOL there are some truth to the OP experience, finding a reputable company is like searching for a honest mechanic or the elusive unicorn....... You would have laugh on the pros I have meet.

 

[oldgoaly]

So many "corporate" service people are nothing but sales people they get a % of the sales as part of their pay. so does it make a difference whether they sell a 50$ part or a 2500$ cheapo furnace replacement. Hell yes! Around here the tinknocker's service units too so it is not likely he didn't know squat, it's slow time now need to make some money! If your name is on the business and you have any credibility you did the best work you could do for a decent and competitive price. My name was on my biz for 27 years, one man shops are history!