Furnace Ignition Problem

Reply

  #1  
Old 12-20-02, 08:51 AM
moe214
Visiting Guest
Posts: n/a
No ignition again! Please Help!

I have a goodman/janitrol electric ignition furnace (model #gmp050-3). The problems started two weeks ago. First, it would not ignite. The blower would start and the ignitor would glow but it would not light. We cleaned the flame sensor and then the furnace started to work fine. It worked for exactly one week and then it stopped again. That time, the ignitor would not glow. We ordered the ignitor and replaced it. The furnace worked great for 2 days and now it is dead again! Now, The blower starts, the ignitor glows, I hear clicks from the gas valve, but it does not light! We tried cleaning the flame sensor again but it didn't work. Please help...can not afford repair man and this has been a never ending nightmare!
 

Last edited by moe214; 12-20-02 at 09:14 AM.
  #2  
Old 12-20-02, 09:18 AM
KField's Avatar
Member
Join Date: Dec 2002
Location: Easton, PA
Posts: 3,245
Received 0 Votes on 0 Posts
The sequence should be 1. call for heat, inducer fan starts. 2 Air pressure switch senses inducer fan operation and switch closes. 3. Ignitor glows. 4. Hear the click which is the gas valve opening. Gas reaches ignitor and flame lights. 5. Flame reaches flame sensor and tells the control that all is well. 6. Ignitor is de-energized and burner stays on until room temp is reached or high limit is opened.

Some of these contitions can be verified visually and some by sound, but it is very dificult for us to get a description from you and point a finger at a bad part. It is better if you fully understand he sequence and can see where the chain is broken. The items below all have some level of control over the heating cycle.

Vent blower, flame sensor, hot surface ignitor, rollout switch, natural gas valve, auxilary limit, circuit board, air pressure switch, door switch, high limit switch.

External to that is gas pressure and electricity, and even routing of the vent.

I had a service call once for no heat and it was just a garbage can sitting right against the outlet on the house blocking the airflow just enough so the fan prover wouldn't let the furnace start. Didn't even have to take the tool box off the truck.
 
  #3  
Old 12-20-02, 09:37 AM
moe214
Visiting Guest
Posts: n/a
thanks

thank you for reply. The ignitor glows. The failure occurs right after the ignitor glows. I believe I hear the gas valve opening. I just noticed something very interesting. About 4 inches of the wire that runs to the flame sensor is black and burned and it was not like that before. What does that usually indicate?
 
  #4  
Old 12-20-02, 09:54 AM
KField's Avatar
Member
Join Date: Dec 2002
Location: Easton, PA
Posts: 3,245
Received 0 Votes on 0 Posts
If the gas valve opens and there is no flame, maybe there is no gas. Or low pressure. You should verify correct pressure at the outlet of the gas valve. You can buy a gauge just for gas pressure checking but if you are trying to save money, you might not want to do that. No other way to check the pressure that I know of. Maybe the gas company could verify it for you but you might get charged for it.

As for the burned wire, there is no current flow in that wire that could possibly heat it up so it must have been caused by a heat source of some kind.
 
  #5  
Old 12-20-02, 10:16 AM
moe214
Visiting Guest
Posts: n/a
flame sensor

is it possible that the flame sensor is not functioning correctly because of the burned wire? I clipped the burned middle part off and reconnected the ends with a orange wire connector. I wonder what burned it, seems strange.

Also, could it be a bad flame sensor? I read a post that stated you can clean a flame sensor but it usually doesn't resolve the problem for very long before it needs to be replaced.

i'm not sure if it's a gas preasure problem because i am not having any problems with my gas stove or hot water heater.
 
  #6  
Old 12-20-02, 11:23 AM
KField's Avatar
Member
Join Date: Dec 2002
Location: Easton, PA
Posts: 3,245
Received 0 Votes on 0 Posts
You said there was a click and no flame. That would not point to a flame sensor. That would point to a lack of flame and even though the flame sensor would be responsible for shutting down the unit, it is doing its job in that case. Find out why there is no flame.
 
  #7  
Old 12-20-02, 05:32 PM
bugsmeso
Visiting Guest
Posts: n/a
OK..my $.02.......remove the burner and clean them as best you can. We have found that the enshot type burners will collect alot of dust and etc and keep the burners from firing properly. If you fill energetic, pull the blower assembly and see if you have any rings laying in it.
 
  #8  
Old 12-20-02, 05:58 PM
hvac4u's Avatar
Member
Join Date: Aug 2001
Location: NW atlanta
Posts: 3,145
Received 0 Votes on 0 Posts
good advice here

i have seen in shot burners corrode to the point of clogging the carryover and cause the burner in front of the sensor to not light, but usually at this time the others burn for 5 to 10 seconds. interesting that bugsmeso would mention rings in the blower, all too common failure in these units is the rings holding the heat exchanger together break. never thought to look for them there, just goes to show that you learn something every day. great idea especially with those goodmans.
 
  #9  
Old 12-20-02, 06:04 PM
bugsmeso
Visiting Guest
Posts: n/a
hvac4u............... did a complex with 42 Junkatrols and within 5 years had replaced 27 heat exchangers....that's what the owner wanted and he even asked for a lower price if they would forget the heat exchanger warranty and the 5 year parts warranty and then Goodman chipped in 140.00 per unit to replace them
 
  #10  
Old 12-20-02, 06:21 PM
hvac4u's Avatar
Member
Join Date: Aug 2001
Location: NW atlanta
Posts: 3,145
Received 0 Votes on 0 Posts
sorry, moe

you have a builders grade unit that in my opinion will continue to give you problem after problem for some time. you do not say how old it is, but the track record for that unit is poor at best. i personally have replaced almost every part of this unit in furnaces less than 3 yrs old. another thought that comes to mind, if the flame sensor wire is burnt, i would look for a roll out condition, since the flame sensor works on very minute current.
 
  #11  
Old 12-20-02, 09:40 PM
moe214
Visiting Guest
Posts: n/a
Question rings??

bugsmeso.....what do you mean by rings laying in the blower assembly? what rings am i looking for.

by the way, thanks to all of you for your help and hints.
 
  #12  
Old 12-21-02, 03:57 AM
bugsmeso
Visiting Guest
Posts: n/a
When the blower is removed and the rings are found.................this is an indication that the heat echanger has failed. When you mentioned the flame sensor wire was burnt or discolored........this could be due to flame roll out.
The clam shell type heat exchangers are actually riveted together with a process. One side has a male side and the other a female, the male is pushed through the female and bent over to hold the heating chambers together....................the with contaction and expansion due to certin usage conditions..........these rivets break and leave a ring..............which fall to the bottom.......some on the lip of the floor where the H/E sits and opthers fall into the blower wheel area. Also Janitrols (I have found) always come over firing and should have the gas pressure checked and adjusted.....we adjust them to 2.8 -3.0 WC.....for longer H/E life. Some installations Goodman suggests pressure regulators be installed
 
  #13  
Old 12-22-02, 10:45 AM
Sharp Advice's Avatar
Admin Emeritus
Join Date: Feb 1998
Location: The Shake and Bake State USA
Posts: 10,398
Received 5 Votes on 4 Posts
Moderator Note

Originally posted by moe214

"I just noticed something very interesting. About 4 inches of the wire that runs to the flame sensor is black and burned and it was not like that before. What does that usually indicate?"

Moderator Reply:
4 inches of burned wire which, if it happens to be very close to the sensor, may indicate a serious problem. Flames are burning out of the firebox, backwards towards the front of the firebox and not inwards, as intended to be. A serious condition termed in the heating industry trade as "Flame Rollout.

This possible condition needs a highly trained and experienced professional to determine the cause of the condition. Such conditions are not do it yourself tasks or projects. Hire a pro.

Flame rollout and or flame smothering conditions are extremely serious and highly dangerous. These condition can cause fires and carbon mononxides to enter the living environment, causing serious health problems and or death...hire a pro.

>>>>>>>>>Note To Mods & Members Posting Replies To Questions On Gas Fired Heaters and Heating Units.

Please read all questions pertaining to heaters very carefully.
The advice we offer & that which we do not offer or suggest in our replies may not provide a safe solution.

Heaters using gas of any fuel type, operating incorrectly, are the number one gas appliance producers of CO. CO is a killer.

As professionals in the industry, we must be alert to key words in a question. If there is any doubts, as pros we should highly suggest to the person asking the question to seek professional on site help. Doing so on our parts is true professional help in a text only format.

Additionally: PLEASE use laymans terms in posting replies.

We as professionals cannot & should not expect persons asking questions, especially heater problems, to know all the terms, technical phrases, purposes for every part or parts, safety devices, etc which may be the cause of any heaters problem.
Use the names and terms but also clearly describe them.

Forum Host & Multiple Topic Moderator.
TCB4U2B2B Company Enterprises. Energy Conservation Consultant & Gas Appliance Diagnostics Technician.
 
  #14  
Old 12-22-02, 11:10 AM
KField's Avatar
Member
Join Date: Dec 2002
Location: Easton, PA
Posts: 3,245
Received 0 Votes on 0 Posts
In our litigious society, I'm already shocked that we don't have to agree to some kind of disclaimer just to enter this forum. It is obvious by the name that it is not for professionals. It should be obvious that nobody here gets paid for giving advice either. If someone does not have enough common sense to know when they are in over their head, carbon monoxide will just be a contributing factor to their demise. Until the government requires only certified individuals to repair HVAC equipment (like the airplane industry) a lot of good equipment will continue to be mis-applied and incorrectly installed and serviced on a shoestring. There is absolutely nothing wrong with doing it onesself except that when it comes time to blame someone, there is nobody there to sue. If I went to the bridge forum and told somebody to jump off, do you think they would?

Keep up the good work because I firmly believe that MANY handy people solve tons of simple problems right here in this forum.

How about if we start every reply with "Don't try this at home"
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: