Ruud rollout switch tripping

Reply

  #1  
Old 01-26-16, 01:42 PM
Member
Thread Starter
Join Date: Nov 2009
Location: Alabama
Posts: 6
Received 0 Votes on 0 Posts
Ruud rollout switch tripping

I have a 2005 Ruud Achiever series 4-ton model RRMA-A048JK10E. One day it stopped heating so the first thing I checked was the breaker. I flipped the breaker off and one to make sure it was not partially tripped. The unit came on and started heating up, then the blower came on and heat started coming into the house. After a few minutes air was no longer coming in so I went outside and the unit was not running. I checked the breaker again and it was not tripped so I called a service tech.

When he arrived and I told him the problem he said it was the rollout switch without even opening it up. When he did open up the front panel he reset the switch with an audible click. He said that confirmed it was a rollout problem and explained what that was.

He then wired it so he could control it from outside without having to go inside to the thermostat. The unit started up again and he (we) watched as it ran. As before after a few minutes the unit shutdown but this time I could see what was happening.

First the vent fan came on, then the burners. They heated for a bit then the blower came on. The system seemed normal for a few minutes then the switch tripped and the burners turned off; as earlier the blower continued until it had cooled enough. Since he had the panel open where the front of the burners and the rollout switch is located we could see there were no visible rollout flames. Anyway, how hot could it get in the switch area with the panel open on a cold day?

He opened the side and removed the blower to expose the heat exchanger chamber and immediately said there was a crack in the exchanger and told me to look inside. I could not see a crack but what do I know.

He said it would cost a couple thousand to replace the heat exchanger but that since the unit is 11 years old (just past the 10 year warranty) we should consider replacing the whole unit. He sent me a quote later for $6900 (unit and labor) for a new 4-ton Carrier. I told him I needed to talk with my spouse. He put the unit back together and was on his way.

Being a bit of a DIYer I started reading the forums and decided for a small price I could replace the rollout switch and while I was at it I would replace the blower limit switch which had gone out once before ($15 for both parts). I opened the unit and found that he had not reconnected the blower limit switch and the wires going to the blower were not put back into the correct slots.

Reading the forums I thought maybe he had done this to keep me from running the unit for my own protection (carbon monoxide, etc.). To me it seemed more like incompetence than concern because he should have informed me of what he had done if he was concerned.

I should mention that shortly before it stopped working (maybe the same day, I am not sure, we had a few warm days so it was not running constantly) I had noticed that leaves had built up under the backside of the unit where it attaches to the duct work under the house. You can not see the actual connections because they have been shrouded with sheetmetal. I used my shop vac with the hose attached to the exhaust to blow the leaves from underneath the shroud.

Again, checking the forums I read that blocked or restricted air flow could cause the heat exchanger to overheat and trip the switch. I changed the air filter (which was a little dirty but not real bad) but that did not help. I also read that a clogged furnace condensation line could cause this problem, however, I can not seem to determine if this model unit is the style that has this. I read that 90% units do and from what I can tell this is an 80% unit.

I hope I have given enough background so here are my questions.

Could I have blown debris into the unit from under the backside? It does not seen likely since it was outside the unit but I thought I should ask.

What else could be causing the heat exchanger to overheat and trip the rollout switch when there are no rollout flames visible?

Are there other switches, capacitors, etc. that I could check/replace?

I really do not have thousands of dollars so if there is anything else I can do myself please help.
 
Sponsored Links
  #2  
Old 01-26-16, 04:08 PM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 5,503
Received 0 Votes on 0 Posts
<<Could I have blown debris into the unit from under the backside? It does not seen likely since it was outside the unit but I thought I should ask.
>>


Unlikely.

<<What else could be causing the heat exchanger to overheat and trip the rollout switch when there are no rollout flames visible?>>



Usually I would expect flames to be visible coming out the from of the burners and licking the flame rollout switch. But anything that heats up the switch can cause the problem.

The most common cause of flame rollout is a soot plugged heat exchanger that prevents the combustion gasses from burning properly and going out the vent. When that happens, partially burned combustion gasses come out the front looking for air to burn.


While the burner is operating, disconnect the pressure switch to see if that causes the burners to shut off ---it should.

Try putting a finger on the flame rollout switch while the burners are operating to see if it's getting hot. If it is, you need to be a good observer to see if you can identify the cause.

A repairman who offer to SHOW you a crack in the heat exchanger is probably NOT BSing you. I used to offer to show my customers cracks, which they might not always be able to see.

As a util;ity repairman, I recal;l being called in for a second opinion when a private contractor reported a crack. When I didnt see any, he lamely said (Oh, it must have been a spot of rust."
 
  #3  
Old 01-26-16, 10:38 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 52,556
Received 331 Votes on 309 Posts
A recommendation I'd make is to call your gas supplier and have them send a service tech to check it out. Their prices are fair, the guys are well trained and they don't push to sell furnaces.
 
  #4  
Old 01-28-16, 07:32 AM
Member
Thread Starter
Join Date: Nov 2009
Location: Alabama
Posts: 6
Received 0 Votes on 0 Posts
SeattlePioneer: I have not tried your suggestions to disconnect the pressure switch or putting my finger on the rollout switch, yet. I did get down on my knees and looked into the heat exchange tube where the flames are shooting in. In one of the tubes I noticed a few spots of buildup of some sort that the flames are burning causing then to glow like embers. Could this be soot like you mentioned? Could that be causing the problem? Can the tubes be cleaned instead of replaced as a first attempt? Any idea how much it should cost to clean them?
 
  #5  
Old 01-28-16, 07:35 AM
Member
Thread Starter
Join Date: Nov 2009
Location: Alabama
Posts: 6
Received 0 Votes on 0 Posts
PJmax: Thank you for the suggestion. I will consider them for my second opinion.
 
  #6  
Old 01-28-16, 11:48 AM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 5,503
Received 0 Votes on 0 Posts
<< In one of the tubes I noticed a few spots of buildup of some sort that the flames are burning causing then to glow like embers. Could this be soot like you mentioned? >>


Probably not.

Normally you have gas and combustion air going into the furnace near the burners and going through the heat exchangers and out the vent.

If sooting occurs, it usually plugs up the heat exchanger, blocking that flow of gases into, through, and out of the furnace. Since those gasses can't go up the vent, they start coming out the front of the furnace, tripping the flame rollout switch.


A trivial amount of rust isn't going to cause that. But you should use a flashlight and mirror to verify that what you are seeing isn't soot ---because any soot accumul;ations require service to avoid the bigger problem and mess I've described.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


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