GAS FURNACE HELP

[Ruger Rich]

I've got a gas furnace acting up. I've done many of the logical things to the extent of my knowledge. So I guess it's time to call a tech in. Any of you folks have a good experience recently with gas furnace repair person and like to share with me, I would most appreciate that. I live in Milwaukie.

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[Martini_Up]

My furnace is about 17 years old and when acting up has a strobe light which defines what the problem is (a key is on the outside defining what the strobe means...2 long, one short for example means starter is out) I guess there's some telemetry going to a small computer which makes trouble shooting a cinch.

Does yours have something like this?

 

[asbtg]

What's it doing (or not that it should)?

 

[jbett98]

A neighbor called me the other day and said that their gas furnace wouldn't start the combustion cycle.
I watched it start the heating chamber flues exhaust fan, then it went to energize the ceramic ignition strip and it failed to glow, so I assumed it was a bad ignition strip, but come to find out after installing a good spare, it was the air pressure switch not being closed after it called for the exhaust fan. That's step 2 in the programmable cycle.

I then opened the cabinet where the circuit board is located and then I counted the little LED flashing light. Two flashes meant that the fan pressure switch was faulty.
I removed the red silicon air hose off the fan and blew towards the pressure switch and it clicked the switch, so I switched ends and blew towards the fan housing and found it was blocked by accumulated exhaust debris.
All it took was a small flat bladed screwdriver to open the hole back up.

Inside that panel will be a step by step procedure list when it's running correctly.
If the process is interrupted, then the flashing light will flash the appropriate times to tell you were the cycle was interrupted.

Some units will lock off the furnace after so many times it fails to ignite.
You then need to turn off the power to the unit for a minute and then count the flashing lights after you restore the power. There should be a switch on the side of the furnace.

There also a safety switch on the door of the fan compartment, so you need to manually hold it down while you watch the circuit board.

 

[RicInOR]

@Ruger Rich
I just had this issue in December. The heat sensor was misreading. Furnace come on, before fans would kick in, showed over hot, shut down combustion. Fix on my 20+ year old unit was a new controller about $450. But, at least it was a national brand so parts are available.

Furnace tech I would recommend, but they are from Beaverton which is a ways from Milwaukee. And Milwaukie.

PM if you want his phone.

 

[Lilhigbee]

We've had Petra do some work for us at our rental house. First class all the way.
Contact Us – Petra Heating & Air Conditioning

 

[jb11]

Is it giving you a code to look at? What exactly is it doing?

 

[Ruger Rich]

Thank you all, I've got something to work with now. It's a 30 year old Lennox, so error indicators are not there. The furnace comes on, the inducer runs, the igniter ignites, the pilot flame comes on and the sensor signals that the pilot flame is on. Here's where it gets hinky. The gas valve energizes and then drops out, and it'll do this over and over. Occasionally the burner will fire up and then shortly go out. I've a spare control module which I've replaced to no avail. And I'm guessing 30 years is a respectable time for a furnace to live. Perhaps it's like dog years, 30 furnace years equals a humane lifetime.

 

[jb11]

Sounds like your gas valve is going bad.

 

[Ruger Rich]

Sounds like your gas valve is going bad.

Thank you and I'm inclined to agree. A long time ago when I was young and lived for cars and girls I learned, financially painful, that throwing parts at a problem until you got lucky was not the way to troubleshoot. And the gas valve is probably the most expensive thing in that furnace. Maybe it's time to flip a coin.

 

[Aispuro]

I recently just had problems with mine but ended up switching to electric an going with the on demand models Highly recommend it.

 

[308]

Our gas furnace went tizup so I bought a new gas train from HVAC Industrial Controls Distributor > Home

...and installed it myself...easy/peasy

 

[RicInOR]

a 30 year old Lennox,

Replace. Get high efficiency & Get the dealer to help with rebates.

if it was 20, I'd say repair.

 

[Ruger Rich]

Replace. Get high efficiency & Get the dealer to help with rebates.

if it was 20, I'd say repair.

Appreciate the advice, input from multiple sources helps with a decision. Also, I mostly respect the opinions of the folks here.

 

[jbett98]

Replacement gas furnaces are rather cheap nowadays. It's the labor involved in removing the old unit and then having the transition duct work made to order along with hooking up all the attachments.
If an HVAC company is involved, then you're paying way more then having a moonlighting service guy do it over the weekend for cash.

 

[Martini_Up]

Maybe..... Clean the flame indicator? A little rod in the flame that tells the system it started.... if dirty doesn't know it started and will kick it all off until the thermo starts again. Will cycle a few times then rest for some hours. Steel wool the carbon off or repack it.

 

[gunnails]

I have a 7 year old Lennox and was having trouble with it, I had 4 different H-Vac companies out to fix it with out luck. They all went through the same procedures to try to get it going with out luck, The problem is it's a Lennox and most companies do not have experience with them. and I had issues with the company who installed it so they were not called. After a long wait the furnace would manage to come back on and work for weeks or months. finally it stopped all together.
So called the big furnace distributor guy's in Portland, and asked them who was the best Lennox repair guys. They recommended Wolfords.
So I called Wolfords and asked for there best tech, and they said that would be the service manager but he wouldn't be able to look at it for 4 weeks (it was January of 2017) I told them I would wait. Used space heaters for the 4 weeks.

The guy walked in took one look and said you have the old style manifold, he went and picked up the new style larger manifold, installed it, and the furnace has been money every since.

So don't get a Lennox, there decent units but most techs don't know how to service them.

 

[RicInOR]

+1 on Wolfords

 

[jb11]

Did you get it fixed?

 

[joken]

I suspect the pilot flame is weak and when the main burner comes on the additional draft is pulling the flame off the flame rod. It is also possible that it's the circuit board. Electrical current passes thru the pilot flame to the flame rod and the board sees this, or not if the board is going out. It could be a couple other things, but this is most likely. If the pilot is impinging on the flame rod and nice and blue, I'd clean the flame rod with some fine sand paper or what you have. If the pilot flame is soft, you can remove it and try to clean it with compressed air. The pilot orifice is tiny and any attempt to clean it without some jewelers drills will ruin it. Typically the orifice is replaced. I used to be the HVAC guy for many too years.