Rheem flame sensor, round two...


  #1  
Old 12-27-03, 12:02 PM
B
Member
Thread Starter
Join Date: Dec 2003
Posts: 123
Upvotes: 0
Received 0 Upvotes on 0 Posts
Rheem flame sensor, round two...

This is a follow up to my previous post. I did install a new flame sensor rod, and the furnace worked for 6 days. I then called a different Rheem contractor. The unit went into a soft lockout while their tech was trying to solve the problem. Well, he couldn't figure it out either. He called a service "hotline" to find out if there were any service tips or known problems. After being on the phone for about 15 minutes, the two of them decided to try the pressure switches. There are two in my furnace. He went to get the new switches, and of course the parts house didn't have them. They had to order them. So, I'll have to wait a few more days to see what happens.

I was also out shopping and I saw a man wearing a Ruud jacket. So, naturally, I approached him and asked if he could help me. He was a nice guy and asked what problem are you having? I told him about the flame sensor, and replacing it. And that it started doing the same thing again. Going into lockout. He said it's still a flame sensor problem, and his first suspect would be the circuit board. I thanked him and asked if he could do warranty work on a Rheem. He said he could, but he was a one man operation, and he was leaving for Florida that evening for six weeks. I mentioned the circuit board to the tech who came out, and he doesn't think that's the problem. He said he remembered some problems with pressure switches. A tech from the company that installed the furnace also mentioned the pressure switches, but they didn't replace them. What do you experts think?

BTW, I'm getting heat, when the furnace doesn't run, from a kerosene heater and a couple of ceramic heaters, but this is getting rather old, and I'm starting to get cranky about it.
 
  #2  
Old 12-27-03, 07:12 PM
Jay11J's Avatar
Member
Join Date: Sep 2001
Location: Rochester, Minnesota
Posts: 16,984
Upvotes: 0
Received 0 Upvotes on 0 Posts
I would check your power line..

make sure your Black (or red) wire is HOT
Your white wire is NOT hot
and ground wire grounded.

I've had this problem in the past by changing out the parts you've mention, and learn that the main power line feeding the furnae was wired wrong in the breaker box.
 
  #3  
Old 12-27-03, 09:34 PM
rav12's Avatar
Member
Join Date: Oct 2003
Location: California
Posts: 650
Upvotes: 0
Received 0 Upvotes on 0 Posts
I remember the previous posts on this. What are the symptoms you are having. With a flame sensor problem the furnace should fire up and then go into lockout. The controller on the board should not look at the flame sensor signal until it has activiated the ignitor. With a pressure switch fault the furnace can lockout after starting but before ignition has even taken place. Intermittent faults like this can be very hard to troubleshoot. It could well be the pressure switches but it is becoming a guessing situation now. Hope you don't end up changing all the parts in the furnace - unless it is being done under warranty of course.

One tip - see if you can tap/wiggle the board and the other components while it is running and see if you can cause lockout. This may help point to the cause.
 
  #4  
Old 12-30-03, 02:35 PM
B
Member
Thread Starter
Join Date: Dec 2003
Posts: 123
Upvotes: 0
Received 0 Upvotes on 0 Posts
Symptoms are the furnace may or may not fire up. What happens is all the ordinary noises are made. ID fan comes on, furnace attempts to light, maybe it will, maybe it won't. If it won't light, the burner will run for about 5 seconds then shut down. It will repeat this cycle 4 times, I think. If it doesn't fire up in 4 tries, it goes into lockdown. The green led on the left will flash once, and the green led on the right stays on. Sometimes it will fire up on the 2nd, 3rd, or 4th attempt. The Ruud guy says this is symptomatic of a flame sensor problem. The unit is still in warranty. It has the 5 year warranty.

The new tech checked polarity and voltages at the switch behind the front service panel, so I guess we can rule that one out. The Crane that was on the circuit didn't have any problems outside of a fan/limit switch, and a couple of thermocouples.
 
  #5  
Old 12-30-03, 06:05 PM
rav12's Avatar
Member
Join Date: Oct 2003
Location: California
Posts: 650
Upvotes: 0
Received 0 Upvotes on 0 Posts
Your post is not too clear to me but I think what you are saying is that ignition always takes place but sometimes cannot be sustained.

This is consistent with a flame sensor problem although the fault may be on the board rather than the sensor itself.

Another reason could be related to the gas valve - either it is faulty or a fault on the control board could be causing the gas valve to open and then close shortly afterwards.

A faulty pressure switch could also cause this but if the fault is truly intermittent ignition may not even occur sometimes.

In both cases it should be possible to use a multimeter to check the sensor circuit and the gas valve circuit. Have the techs done this when they visited.
 
  #6  
Old 12-30-03, 07:14 PM
B
Member
Thread Starter
Join Date: Dec 2003
Posts: 123
Upvotes: 0
Received 0 Upvotes on 0 Posts
No tech has tried checking the board.

When it fails to start, the burners will fire for about 5 seconds, then quit. About 30 seconds later, another attempt is made to light the burners. It may or may not fire up. If it fails to light, the burners usually fire for about 5 seconds before shutting down. I think this furnace makes 4 attempts before going into lockdown. It's intermittent. It doesn't do it all of the time. It may go for a week without doing it, or it may do it 4 or 5 times a day. It's frustrating.
 
  #7  
Old 12-30-03, 07:31 PM
hvac4u's Avatar
Member
Join Date: Aug 2001
Location: NW atlanta
Posts: 3,049
Upvotes: 0
Received 0 Upvotes on 0 Posts
anyone cleaned the flame sensor yet?
 
  #8  
Old 12-30-03, 07:44 PM
B
Member
Thread Starter
Join Date: Dec 2003
Posts: 123
Upvotes: 0
Received 0 Upvotes on 0 Posts
Flame sensor rod was replaced a few days ago. See my first post regarding the flame sensor for that story. But yes, the rod has been cleaned, even the new one!!!
 
  #9  
Old 12-30-03, 08:01 PM
hvac4u's Avatar
Member
Join Date: Aug 2001
Location: NW atlanta
Posts: 3,049
Upvotes: 0
Received 0 Upvotes on 0 Posts
if the pressure switch is not dropping out, board sounds to be the problem. what kind of flue vent does it have, length, etc. it fires every time but only for a few seconds sometimes, right? tighten all ground wires...flue gas is heavier once the flames come on, making more of a load on psi switch..had one last year, similar, replacing switch did not help but repositioning it did. do not know why
 
  #10  
Old 12-30-03, 09:49 PM
rav12's Avatar
Member
Join Date: Oct 2003
Location: California
Posts: 650
Upvotes: 0
Received 0 Upvotes on 0 Posts
If you have a soldering iron why don't you take the board out and briefly melt all the joints,add a dab of solder to each pad, put it back and see what happens. It may be a dry joint on the board.

Interesting fault about having to move the pressure switch in hvac4u's post. Seems to me that either the pressure switch was failing and moving it simply improved the air pressure to it making it work or it was just a poor design.
 
  #11  
Old 12-31-03, 05:12 AM
B
Member
Thread Starter
Join Date: Dec 2003
Posts: 123
Upvotes: 0
Received 0 Upvotes on 0 Posts
The pressure switches have not been replaced, yet. Still on order. Tech from the original contractor suspected pressure switches, yet they did not replace them. Tech from new servicer also suspects the pressure switches.

Yes, it will fire everytime, but may not stay fired up. If it is not going to ignite, it will light for a few seconds and go out. Flue may be 10 feet. Single story house. Flue was replaced to ceiling. The rest was inspected to be sure it was clean and serviceable. Plenty of "steam" can be seen coming from it when furnace is on.

Fortunately, it has been warmer than usual, but the winter is supposed to arrive next week.
 
  #12  
Old 12-31-03, 08:19 AM
rav12's Avatar
Member
Join Date: Oct 2003
Location: California
Posts: 650
Upvotes: 0
Received 0 Upvotes on 0 Posts
It should be possible to jumper across the pressure switch to see if the problem goes away. I guess they did not do this either. Doing this should be able to tell whether it is the presure switch without having to order new ones.
 
  #13  
Old 12-31-03, 09:23 AM
Jazz3D1
Visiting Guest
Posts: n/a
Questions Re your problem

Bruiser, after reading your post, I believe we both may be having the same problem, but I wanted to get your personal suggestion. Please read my post when you get the opportunity (Intermittent Heat). Secondly, is there a particular way to clean your flame sensor, or would you suggest replacing it?
 
  #14  
Old 12-31-03, 09:46 AM
B
Member
Thread Starter
Join Date: Dec 2003
Posts: 123
Upvotes: 0
Received 0 Upvotes on 0 Posts
RAV12, where do you put the jumper wire on the pressure switches? I have two switches on this model. I'll try it myself and see what happens.
 
  #15  
Old 12-31-03, 11:04 AM
rav12's Avatar
Member
Join Date: Oct 2003
Location: California
Posts: 650
Upvotes: 0
Received 0 Upvotes on 0 Posts
bruiser - you can jumper at any convinient point - either on the board or at the switch itself - anywhere that is easily accessible. The idea is to just short the two wires - this will simulate a closed switch. You should only do it for as long as needed to prove the point since the pressure switch is a safety device - it prevents the furnace form running if the exhaust motor fails. You can just remove the connector from the switch and then short the two contacts with some wire.

Jazz3D1 - you can use steel wool to clean the flame sensor.
 
  #16  
Old 01-01-04, 02:27 PM
B
Member
Thread Starter
Join Date: Dec 2003
Posts: 123
Upvotes: 0
Received 0 Upvotes on 0 Posts
Riddle me this. I have noticed, while cleaning the flame sensor rod all those times, that the furnace would fire up practically every time with the service doors off, and me pushing the safety switch. It was locked out this morning, and I was trying to get it to fire up, so I left the bottom panel off, the one that gives access to the burner compartment, and it fired up and has not locked out all day. Is this a clue to something, or is it just coincidence? The only thing I could think of was that this allowed slightly more air to circulate in the chamber, and maybe something was getting to hot and shutting down, and this let enough additional air in to keep the temp down. The pressure switches are also in this compartment.
 
  #17  
Old 01-01-04, 07:16 PM
Jay11J's Avatar
Member
Join Date: Sep 2001
Location: Rochester, Minnesota
Posts: 16,984
Upvotes: 0
Received 0 Upvotes on 0 Posts
Leave the top panel off, and put the blower panel back on, and run it for a few days and see what happens.

If the system runs fine the whole time, then chances are it may be tripping on burner roll out.. or some other sensor that may be in the burner area.

on the 80% furnace, it should have enough air flow into the burner area to keep it going. (if yours isn not a seal combuton system using pvc pipe)

The pressure switch shouldn't have anything with the service panel off.
 
  #18  
Old 01-01-04, 07:39 PM
B
Member
Thread Starter
Join Date: Dec 2003
Posts: 123
Upvotes: 0
Received 0 Upvotes on 0 Posts
This is an RGLK downflow, and the top service panel covers the circuit board, blower, pushes or releases the safety switch, etc. The lower panel covers the burner chamber. It still hasn't failed to start. It is also the 80 plus, I think they call it. In order to leave the top panel off, I'd need to come up with some kind of clamp to push and hold the safety switch. The tech is supposed to be here Friday, so I'll mention this to him.
 
  #19  
Old 01-02-04, 04:17 AM
mattison's Avatar
Member
Join Date: Mar 2003
Location: Cinti, OH
Posts: 5,315
Upvotes: 0
Received 0 Upvotes on 0 Posts
Leaving the blower door off the unit itself allows it to run without shutdown? Sounds like you have a lack of return air then. Check all your return vents to be sure none are covered and also what type filter are you using? and has it been changed ?
 
  #20  
Old 01-02-04, 05:10 AM
B
Member
Thread Starter
Join Date: Dec 2003
Posts: 123
Upvotes: 0
Received 0 Upvotes on 0 Posts
The blower door is still on. The door to the burners is off. The filter was changed a couple of days ago. I could still see through the replaced filter without holding it up to a light. I don't think it was the filter. What could be in the burner chamber that could be affected by more or less air getting to it? It hasn't locked out since removing the door to the burner compartment. Of course it could be coincidence.
 
  #21  
Old 01-02-04, 08:27 AM
hvac4u's Avatar
Member
Join Date: Aug 2001
Location: NW atlanta
Posts: 3,049
Upvotes: 0
Received 0 Upvotes on 0 Posts
interesting.....how big is the room the unit is in? could be starved for combustion air....just a thought
 
  #22  
Old 01-02-04, 09:32 AM
B
Member
Thread Starter
Join Date: Dec 2003
Posts: 123
Upvotes: 0
Received 0 Upvotes on 0 Posts
It is in a small room, not much bigger than a closet. The door to it is louvered, and the old furnace had no problem.
 
  #23  
Old 01-02-04, 10:51 PM
rav12's Avatar
Member
Join Date: Oct 2003
Location: California
Posts: 650
Upvotes: 0
Received 0 Upvotes on 0 Posts
If the lack of return air was so severe to cause this I would have thought that would hardly be any airflow thorough the ducts at all.

If combustion air was a problem would the furnace shut down or would poor combustion occur. I'm not sure if furnaces are equiped to sense poor combustion or lack of combustion air.

If the door being open does make it work another thing to check for is to see if any wires or similar objects are being affected by the door being closed. Temp could be an issue but since shutdown seems to occur so fast I'm not sure the interior of the compartment would have had time to get up to any kind of reasonable temperature.
 
  #24  
Old 01-03-04, 06:44 AM
B
Member
Thread Starter
Join Date: Dec 2003
Posts: 123
Upvotes: 0
Received 0 Upvotes on 0 Posts
Well, the pressure switches didn't come, so the tech didn't show up Friday. Parts my be here Monday. I'm gonna be sure to mention the service panel deal. Of course this could be a coincidence, as sometimes the furnace will operate properly for days at a time. BTW, I've watched the flame, and it is always blue, no yellows or reds.
 
  #25  
Old 01-05-04, 01:40 PM
B
Member
Thread Starter
Join Date: Dec 2003
Posts: 123
Upvotes: 0
Received 0 Upvotes on 0 Posts
Latest update. Tech was here with pressure switches. Didn't fix the problem. He did several things, like running an extra ground, replacing flame sensor rod, running electric cord to a different outlet to see if it worked better, checked gas valve. Then noticed the yellow led would flash and stay steady. This means there is a weak flame sensor signal. The manual that came with the furnace says that when every other test has been run, and the problem still exists, it is a problem in the main circuit board. Guess what? Neither the tech nor his shop had a board. He calls someone else, and they tell him not to mess with it anymore, and for me to go back to the original contractor. There's another contractor on my s list. Called the original contractor, and got the owner, for a change, and he said he fired the two techs who were here previously. He didn't know I was still having problems. He's bringing a new board out himself tomorrow. Guess I will see what happens. I've already contacted Rheem about what's been going on. I'm waiting to see if anything is going to come of that. I think I am going to write Rheem a letter as well, so this can be documented.
 
  #26  
Old 01-06-04, 12:52 PM
B
Member
Thread Starter
Join Date: Dec 2003
Posts: 123
Upvotes: 0
Received 0 Upvotes on 0 Posts
Original contractor came back today. He took one look and removed the circuit board. He looked it over and said I don't think it was grounded because this mounting peg isn't pushed all of the way into the board. To test the theory, he remounted the board and reconnected everything, and pushed down on the side of the board that has the ground. Lo and behold, it worked. The yellow flame sensor LED stayed on steady. He said the previous techs should have found that problem, and he got rid of them because they couldn't seem to fix things, or were trying to steal business from him. I hope that fixed it. So far, so good.
 
  #27  
Old 01-06-04, 03:23 PM
Jay11J's Avatar
Member
Join Date: Sep 2001
Location: Rochester, Minnesota
Posts: 16,984
Upvotes: 0
Received 0 Upvotes on 0 Posts
Good to see he found the problem.. and sure hope you don't have to "Baby Sit" it anymore now with the cold spell. and get your full night's of sleep!

Thanks for keep us all posted, and updated! :-)
 
  #28  
Old 01-07-04, 06:50 PM
B
Member
Thread Starter
Join Date: Dec 2003
Posts: 123
Upvotes: 0
Received 0 Upvotes on 0 Posts
Although it's only been something over 24 hours, the furnace has fired up first time, everytime, at least while I'm awake. Yeah, I can sleep now without "furnace fighting". You'll shoot your eye out, kid.
 
 

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