Gas Furnace problem -Old Lennox-

[CWloop]

-Hi all

I'm having a problem with my old 28yr old Lennox.

When the furnace runs it will run for about one to two minutes and then it will flame out,blower continues to run , it cools down and then it will re-fire.

So I guess the unit is running too hot?

To make a long story short a Tec came out,on the ticket he diagnosed it as a faulty gas valve,I replaced it and the problem still continues.
I call the company back out and Tec # 2 says the controller was bad so I replaced it.
The problem still continues.

Wile watching the unit go through it cycle last night I decided to pull open the filter door ,the unit continues to run as normal ,the problem goes away and it never goes off on high limit.

"The filter is new and there is nothing blocking the duct"

So I'm thinking its the blower motor or the Capacitor.But The motor spins freely and does not get hot.The capacitor looks ok but I have no Idea yet on how to test it or if even the will cause the motor to run slower or if this is the problem at all.

I'm so pissed with the company I don't want them back.

Could someone be so kind to head me In right direction,your thoughts or suggestions would be greatly appreciated.

Thanks
-CW

[snupytcb]

when was the last time it was serviced?

[jpsmith1cm]

IF, and that is quite a large IF, it is indeed cycling on high limit, random parts replacement will not resolve the problem.

You need to correct the root cause which is probably related to the ductwork and not the furnace.

[Gross]

IF, and that is quite a large IF, it is indeed cycling on high limit, random parts replacement will not resolve the problem.

You need to correct the root cause which is probably related to the ductwork and not the furnace.

:ditto:


im sure it doesnt help that your system is 28 years old either

[pacnw]

did the "company" replace the parts or did you?

[CWloop]

Snupytcb- It get serviced regularly .


Jpsmith1cm- Are you saying the returns may need cleaning?They look ok.The duct work itself hasn't changed .I will pull the returns down and have a closer look.

Gross - yes its old but its been very reliable up until now.I think a lot of Tecs today just don't know the older units.First thing they want to do of course is sell ya a new unit.
The heat exchanger is still in great shape !

Which one of the newer units have battle ship metal heat exchangers ? "Grin"

[skippedover]

I'm assuming this is a gas furnace and not oil? No specific equipment information doesn't give us much to lean on. Even a few pictures would at least tell us with what we're dealing. A good company should obtain the following information as they perform a thorough trouble shooting job. These won't necessarily mean anything to you but should to a good tech.

RAT, SAT, RESP, SESP, TESP, CFM. This is information that is germane to both oil and gas units. For gas furnaces, inlet gas pressure in IWC, manifold pressure in IWC, total Btu input to the furnace by clocking the gas meter. The tech may find the problem without going through all those steps but if necessary, all steps should be taken.

However, if the problem is NOT temperature related, then the possibilities are almost endless. I appreciate your frustration with the servicing company but please understand that not all techs are cracker jack aces and if the problem is beyond basic, it may take a senior tech to solve the problem. Now if THEY have been putting on the parts, I'd expect them to stand behind their work. Btu if YOU have been replacing the parts based on their opinion, then you've got no recourse for what's been done. It's difficult to determine who's on first by your description.

[tinknocker service tech]

your unit may be border line on return
what type filter are you useing if 3m then pull it and put in a cheap one

the evape coil may also be plugged and need a good cleaning
age IMHO isnt your issue
something has changed and needs to be found if in fact it is over heating and not something else causing your problem

what ever you do
DO NOT LEAVE THE BLOWER DOOR OFF OR YOU COLUD DIE

[jpsmith1cm]

Snupytcb- It get serviced regularly .


Jpsmith1cm- Are you saying the returns may need cleaning?They look ok.The duct work itself hasn't changed .I will pull the returns down and have a closer look.

Gross - yes its old but its been very reliable up until now.I think a lot of Tecs today just don't know the older units.First thing they want to do of course is sell ya a new unit.
The heat exchanger is still in great shape !

Which one of the newer units have battle ship metal heat exchangers ? "Grin"

Actually, I'm referring to a potential airflow problem.

I cannot see the installation from here, but the symptoms that you describe MAY, and I must emphasize MAY be a low airflow problem.



I'll turn your last question about on you. How many NEW units operate at typically 50-60% fuel efficiency?

[CWloop]

I'm assuming this is a gas furnace and not oil? No specific equipment information doesn't give us much to lean on. Even a few pictures would at least tell us with what we're dealing. A good company should obtain the following information as they perform a thorough trouble shooting job. These won't necessarily mean anything to you but should to a good tech.

RAT, SAT, RESP, SESP, TESP, CFM. This is information that is germane to both oil and gas units. For gas furnaces, inlet gas pressure in IWC, manifold pressure in IWC, total Btu input to the furnace by clocking the gas meter. The tech may find the problem without going through all those steps but if necessary, all steps should be taken.

However, if the problem is NOT temperature related, then the possibilities are almost endless. I appreciate your frustration with the servicing company but please understand that not all techs are cracker jack aces and if the problem is beyond basic, it may take a senior tech to solve the problem. Now if THEY have been putting on the parts, I'd expect them to stand behind their work. Btu if YOU have been replacing the parts based on their opinion, then you've got no recourse for what's been done. It's difficult to determine who's on first by your description.


Thank you for your response.

The company I called charges bucks for a diagnostic to find the problem.My reason for me doing it this way was to save money on labor the company would have charged to replace the part or parts needed.

I consider myself mechanically inclined enough to do the work.However I don't have the tools or knowledge to diagnose properly and didn't want to throw parts at it,even though thats what I wound up doing anyway and even payed extra:gah:

The company didn't charge me for the second Tec visit, only the first time for the diagnosis.There was nothing wrong the the work I did,it was diagnosed wrong from the start.

I wasn't home home when the first guy came out so I don know what he did .The second guy only had a multimeter and somehow determined the gas valve was bad which it was not.


In a perfect world I think I could of saved some money,my intentions were good but I think got screwed in the end .

BTW its a Lennox Gas Furnace ,the description is in the post title.I can post more info and pics if need be.

Thank you for your reply
-CW

[jpsmith1cm]

Removed pricing

[CWloop]

The filter door is on the return side not the supply side,the flow at the registers/vents still has good flow.

I checked the fins on squirrel cage and there clean too.I have a cheap filter,fiberglass kind.

Couple pix of the unit and the unnecessarily replaced parts.If The the A coil was clogged why does the unit operate normally with the filter door open?

[CWloop]

Actually, I'm referring to a potential airflow problem.

I cannot see the installation from here, but the symptoms that you describe MAY, and I must emphasize MAY be a low airflow problem.



I'll turn your last question about on you. How many NEW units operate at typically 50-60% fuel efficiency?


Thank you for your opinion.


Point well taken on your last question.
I think the new units are great on efficiency.

[hearthman]

bzzline, This is the Ask Our Pro's or AOP forum. In order to post responses here, you must have verified qualifications and have been approved by the AOP Committee. Please see my signature line for links to register and review the AOP Forum Rules. Thank you. Your post will now be deleted. Further infractions may result in loss of posting privileges.

[snupytcb]

you need a reputable service company to look at this. as you said, you don't have the tools needed to properly diagnose this problem. and , no offense, but most likely you don't have the training and experiance. explain your situation to the company and tell them you would like the best person they have to do this. you could just be throwing money at this thing and it may not even be reparable. on top of it could be a safety issue as well. do yourself a favor and try another company. if you look at jpsmith1cm's posts you will see a link for a contractor map. you may be able t use someone on here.

[skippedover]

Thank you for your response.

The company I called charges bucks for a diagnostic to find the problem.My reason for me doing it this way was to save money on labor the company would have charged to replace the part or parts needed.

I consider myself mechanically inclined enough to do the work.However I don't have the tools or knowledge to diagnose properly and didn't want to throw parts at it,even though thats what I wound up doing anyway and even payed extra:gah:

The company didn't charge me for the second Tec visit, only the first time for the diagnosis.There was nothing wrong the the work I did,it was diagnosed wrong from the start.

I wasn't home home when the first guy came out so I don know what he did .The second guy only had a multimeter and somehow determined the gas valve was bad which it was not.


In a perfect world I think I could of saved some money,my intentions were good but I think got screwed in the end .

BTW its a Lennox Gas Furnace ,the description is in the post title.I can post more info and pics if need be.

Thank you for your reply
-CW

Sorry for the poke in the eye about the fuel for the furnace. I noticed too late that you stated "gas" in the title. My bad.

However, the diagnostic error belongs to the company, while the 'saving money' error is only yours. You chose to take their intellectual property, be it correct or incorrect and make the part replacement based on that. They were wrong and you fell for it. Had they done the parts replacements, I suspect you'd have actually saved some money because the problem is not resolved and you'd have to keep calling them back. And of course they charge for diagnostic. How many doctors, lawyers or dentists can you visit and get a diagnosis without paying? Often times the diagnostic is used to offset higher charges for the repairs, though not always.

Our company runs into situations like yours on a regular basis. Some problems are tougher to diagnose than others. Sometimes a highly skilled and experienced tech will put his/her finger on a problem and resolve it in record time because he/she's seen it before. Should he/she not be paid commensurate with that knowledge? And the cost of the repair part is generally quite incidental to the cost of having a person with the knowledge to properly diagnose a problem, as you're finding out. You may be mechanically inclined but you lack the intellectual property to do anything more than remove and replace. You should have shelved you mechanical skills in favor of theirs and enjoyed the savings of them returning two, three or more times to resolve the issue. Now you've already made a couple of bad decisions. Will you continue in that vane?

[mlstark]

Snupytcb- It get serviced regularly .


Jpsmith1cm- Are you saying the returns may need cleaning?They look ok.The duct work itself hasn't changed .I will pull the returns down and have a closer look.

Gross - yes its old but its been very reliable up until now.I think a lot of Tecs today just don't know the older units.First thing they want to do of course is sell ya a new unit.
The heat exchanger is still in great shape !

Which one of the newer units have battle ship metal heat exchangers ? "Grin"

How did you confirm that the heat exchanger is in great shape?

[CWloop]

How did you confirm that the heat exchanger is in great shape?


Saltwater and a torch .

[snupytcb]

:pop:

[CWloop]

:munching:

[pacnw]

not quite sure, but is that a gas flex going through the cabinet?

what is that green glob to the left of the ignition control?

what did saltwater and a torch prove?

if it were our company, any part put on and charged for would be removed and credited until the problem was solved and labor would be minimal to none depending on the situation.

as was stated, you chose to replace the parts yourself and that is the risk taken in a DIY situation, nobody to fault but yourself.

[mlstark]

Saltwater and a torch .

Good luck with that, your trouble shooting skills haven't worked so far, hopefully things will work out for you.

[snupytcb]

[QUOTE=pacnw;12430801]not quite sure, but is that a gas flex going through the cabinet?

i saw that. we can't connect a gas whip inside a furnace here. and those grey ones, like pictured, are not code. they break too easy.

[tinknocker service tech]

unit is pretty clean for the age
the cover should be on the filter box
you may have a problem with the cam-stat limit. they have been known to go bad and not bring the blower on soon enough or the high limit is weak
old g-12 unit also had a problem with the restricture plates at the top of the hx rusting up and not letting enough drat through the HX and it would over heat

you realy need to call the company back and ask them to do a combustion test on the unit and fix it right

[CWloop]

The reason I posted on this site was to hopefully get some constructive ideas , to see if I was on the rite track.
I got some of that and more.
Thing about the internet is you have to wade through the BS comments and separate the good info from the not so good.
Lots of sites like these,you know,filled with cracker jack internet mechanics who read a book once and went to school but have no hands on experience in the field and think they know everything.

Post like Tinknockers and others is why I came here.Thank you...

The rest of you just make yourself look like a bunch of unprofessional know nothing jerks!
If you take a look at one of the old school books,you will find out what salt spray and torch is used for and how to do it if interested.Im sure you wont find it any of your newer high tec literature.

[CWloop]

Good luck with that, your trouble shooting skills haven't worked so far, hopefully things will work out for you.


Mlstark,what can I say,you have a really cool avatar!


Good luck with your "Professional Member status"...it shows !

[snupytcb]

The reason I posted on this site was to hopefully get some constructive ideas , to see if I was on the rite track.
I got some of that and more.
Thing about the internet is you have to wade through the BS comments and separate the good info from the not so good.
Lots of sites like these,you know,filled with cracker jack internet mechanics who read a book once and went to school but have no hands on experience in the field and think they know everything.

Post like Tinknockers and others is why I came here.Thank you...

The rest of you just make yourself look like a bunch of unprofessional know nothing jerks!
If you take a look at one of the old school books,you will find out what salt spray and torch is used for and how to do it if interested.Im sure you wont find it any of your newer high tec literature.

yes, we have those type guy's on here, but the real ones outweigh the wantabees. the salt water trick used to be the way. now, over the years through the thousands of dollars of schooling and countless hours of experiance we know of better more effective ways of diagnosing these things. if not diagnosed correctly it could be deadly. this is why we (most of us) take our trade so seriously. i can't say i am the most professional but as a business owner , a couple, you learn when not to be. we dont want to see you or anybody else get hurt because you were so confident with your very old and unreliable test. and actually most schools i have been to explain the salt test along with other old and neat ways.

[tinknocker service tech]

saltwater and tourch is a good old school way from the old days but to be sure about the shape of the HX is a combustion test by someone that knows how to use it and read it. Also to make sure the unit is firing properly and drafting properly
every one on this site means well and is willing to help within reason. we are also limited to how much help and i may have gone over the limit some

have the unit properly tested and set up

[mlstark]

Mlstark,what can I say,you have a rea
lly cool avatar!


Good luck with your "Professional Member status"...it shows !

The problem with the internet is that it doesn't reflect a voice inflection, i meant no ill will towards you and was not being cynical, sorry that it came out wrong, salt water spray and torch it to look for the flame to change color is well known, but there are much more advanced and proven methods, usually just pulling the blower and a visual with my inspection scope works, again good luck.

[pacnw]

To original poster(OP),
The internets BS goes both ways. There are those that use it to go around the trained professionals because they are too cheap. In some instances this can harm or even kill someone.
For the liability reason, this site chose to limit their exposure and rightly so.
The information provided to us is not complete and can lead to improper diagnosis. Look at the diagnosis provided by those that we actually there, they did not bet it and yet you expect an internet "chat" to solve it.
Sorry I was not taught the torch and salt water best nor have I ever heard of it. I am always open to adding a diagnostic tool to my arsenal if it is sound or practical.
However if there are better waus to do it then I will choose it.