Pilot Steady, Burners won't Ignite

Reply

  #41  
Old 01-15-08, 06:10 PM
LadyButler's Avatar
Member
Thread Starter
Join Date: Jan 2008
Posts: 28
Originally Posted by pflor View Post
If the furnace fires-up again, we are most certain that either the thermostat cable going upstairs OR the thermostat OR both are bad...more on that once you tell me the results of the test I just mentioned in the previous paragraph
Fired up nicely!
 
Sponsored Links
  #42  
Old 01-15-08, 06:22 PM
pflor's Avatar
Member
Join Date: Dec 2007
Location: U.S.A.
Posts: 1,127
Great news...
One more test...your patience must be running thin by now

No more fooling around with the furnace, she's ready to go and keep you guys warm tonight. Put the service door back in place and go back to the thermostat.

Make sure the t-stat is removed, I want only the subbase there...the subbase is that plate with the labeled screws where colored wires are connected.

Put a jumper between terminals "R" and "W" on the subbase and tell me if the baby fires-up again
 
  #43  
Old 01-15-08, 06:38 PM
LadyButler's Avatar
Member
Thread Starter
Join Date: Jan 2008
Posts: 28
Please hold while I locate the one screwdriver small enough to fit those screws. My three year old must have absconded with it...
 
  #44  
Old 01-15-08, 06:46 PM
LadyButler's Avatar
Member
Thread Starter
Join Date: Jan 2008
Posts: 28
5 year old to the rescue!

(And we have success... fires up nicely!)
 
  #45  
Old 01-15-08, 06:51 PM
pflor's Avatar
Member
Join Date: Dec 2007
Location: U.S.A.
Posts: 1,127
O.K. that's superb news...

o.k., o.k., I lied...I said in the last posting that it would be the last test...but I have one more and I promise there will be no more. (then again, men can't be trusted)

Remove that jumper, put the thermostat back in place (mount it back on its subbase) and call for heat with the t-stat.

If the unit fires-up, the thermostat is good, and the only problem was that tripped safety switch, the rollout.

Let me know...
 
  #46  
Old 01-15-08, 06:56 PM
LadyButler's Avatar
Member
Thread Starter
Join Date: Jan 2008
Posts: 28
Originally Posted by pflor View Post
O.K. that's superb news...

o.k., o.k., I lied...I said in the last posting that it would be the last test...but I have one more and I promise there will be no more. (then again, men can't be trusted)

Remove that jumper, put the thermostat back in place (mount it back on its subbase) and call for heat with the t-stat.

If the unit fires-up, the thermostat is good, and the only problem was that tripped safety switch, the rollout.

Let me know...
He he. I already tried that one before I took the thermostat off to do the last test. No dice there.
 
  #47  
Old 01-15-08, 07:13 PM
pflor's Avatar
Member
Join Date: Dec 2007
Location: U.S.A.
Posts: 1,127
Epilogue

O.K. then...
Thermostat is bad and the other problem you had was a tripped safety.

I'll borrow from President Bush that phrase:
Mission Accomplished [but here we're for real]

I don't like the fact that the flame rollout switch was tripped. Granted, could just be a nuisance tripping that has no bearing on the operational safety of your unit (or the safety of your house!!!!)...but this switch (under normal circumstances) trips when a live flame rolls backwards, meaning, instead of burning by the heat exchanger, it moves towards the service door, and that is a dangerous condition.

How can we know if flame did indeed rolled back and out of the heat exchanger?
Are there any clear marks of flame burns on the service door? I did not see any flame-burn marks in any of the pictures you posted. So it's likely just a nuisance tripping...but double check!

Why does flame rolls back? There are four likely scenarios:
(1) that mechanical room where your furnace is installed is not getting sufficient air for combustion,
(2) you have serious down-draft problems through your chimney which may not only bring cold air down towards the furnace (which is why you need to re-lit that pilot every now and then), but hot combustion gases may be also pushed downwards by the windgusts, and that caused the tripping of the safety switch,
(3) the vent pipe is undersized (this is highly unlikely)...if you wish, let me know sometime what's the diameter of this vent (techs also call them "smoke pipes"), just so I compare its size to what Rheem says the right size should be, and
(4) a cracked heat exchanger...which really means that your furnace would then be ready for the retirement home. Checking for cracked heat exchangers is something that needs a special tool, called "the scope", which I'm sure you won't have at home, so an HVAC contractor would have to look at it. If you smell combustion gases each time the furnace fires-up, it is possible that the heat exchanger has one or more cracks (but it could smell for unrelated reasons as well).

Anyway, go buy yourself a new thermostat.
I purchased last week some Honeywell FocusPro-6000. They are digital and programmable. But any maker would do. I paid aobut $60 or so for each one of the t-stats I mentioned.

Good luck...
You're now an expert on Rheem gas furnaces with standing pilot ignition.
 
  #48  
Old 01-16-08, 02:09 PM
LadyButler's Avatar
Member
Thread Starter
Join Date: Jan 2008
Posts: 28
Epilogue's Epilogue... Perhaps. :)

We replaced the thermostat last night.... and it worked fine- we were nice and warm... for three minutes. Then the switch kicked in again. So we reset. Repeat three or more times.

This morning we were warmer than yesterday morning... but switch was tripped again sometime after my husband went to bed.

I think we had to hit it twice more this morning. The second time I left the cover off... It's been nearly five hours and it hasn't tripped the switch. Is there any explanation for THAT?

Oh and by the way- there have been no burn marks or anything at all to indicate a flame the wrong direction.

I know it's crazy and I don't remember physics as well as I should, but since the furnace closet is in the main hall of our one floor home- a heavy traffic hall that has children running back and forth past it, could air flow from passing people pull the flame slightly in the wrong direction? (That wouldn't account for the last time it went out last night... but it could for just about all the other times.) Just speculating.

Thanks a million for your help. I have two small children and a husband who are thankful as well!
 
  #49  
Old 01-16-08, 03:43 PM
Banned. Rule And/Or Policy Violation
Join Date: May 2007
Location: Wisconsin
Posts: 8,629
I had a furnace doing the same thing about a week ago, and found fan-limit set at 250. Everything mounted to the furnace, including the ignition control was very hot. I lowered the limit to about 220 and have not had to return to this residence after having done so several times before this change I made.

And _I_ had correctly, BTW, diagnosed and replaced a burned out ignition control and mechanical thermostat that went bad during all the short cycling and reseting of the furnace at the roll out limit switch and other resetting of the furnace. There was never any visible roll out of flame before or after the blower motor came on, and that is how I started considering that perhaps heat alone was causing this, when the big furnace cover was installed, as this furnace cover has no fresh air entry through it!, so it was really holding in the heat on the inside.

The furnace would never malfunction when I had the big cover off and was watching everything, even when the limit was at 250. It was only after I put he cover on that the tenant called back up and said the furnace would act up after I had left. That is when I decided to lower the limit setting. And since; no problems.
 
  #50  
Old 01-16-08, 03:54 PM
LadyButler's Avatar
Member
Thread Starter
Join Date: Jan 2008
Posts: 28
So how do I fix that?
 
  #51  
Old 01-16-08, 04:16 PM
Banned. Rule And/Or Policy Violation
Join Date: May 2007
Location: Wisconsin
Posts: 8,629
Can't say for certain my fix will fix yours.

But you have to identify if you have an adjustable limit switch. If you do, you will find a rectangular box device mounted higher than the burners, and may or may not have a cover on it. There are pointers and numbers printed on it inside, if you have that type. Other types you cannot adjust and they are factory set.
 
  #52  
Old 01-16-08, 04:43 PM
pflor's Avatar
Member
Join Date: Dec 2007
Location: U.S.A.
Posts: 1,127
Ecman:
LadyButler's furnace has a Honeywell L4064 fan-limit switch. A high limit setting of about 150F (or so) would work. Decent fan switching settings could be 70F cut-out and 90F cut-in (again...give or take). I do not anticipate the L4064 being defective because the furnace is "not" overheating...if anything, this furnace is shutting itself OFF too early.

I believe her problem is somewhere else (not the L4064). I noted my suspicions about the rollout switch yesterday. Here's my take into what I believe could be happening here:
(a) the switch is plain simply defective and that's why keeps on tripping and should just be replaced, or
(b) there's indeed a flame rollout condition. But to find out if indeed a rollout condition is the problem troubleshooting is needed.

LadyButler:
I've got to take care of a couple of home chores and will be back trying to help.

Ideally, someone (you or your husband) would have to babysit this furnace (remove the service door and sit patiently in front of it), so hopefully the problem occurs while mounting guard in front of it.

Since this is not too practical (and only the luck of the draw would have it that the problem re-occurs while someone is in front of the furnace watching), and with two toddlers around this is even more difficult to do. My advice is to buy a replacement rollout switch. Switch the bad for the new and hope this does not happen again.

In the meantime, please remove the furnace service door, remove also the cover of the Honeywell L4064 (pic follows below) and let me know the settings of the 3 pins. Though I'm quite confident we will find nothing to be concerned about in there.



WHERE TO LOOK FOR THIS SWITCH????
look for part#25 on posting#33...I sent you this pic yesterday (the furnace showing all of its parts)
 
  #53  
Old 01-16-08, 05:26 PM
pflor's Avatar
Member
Join Date: Dec 2007
Location: U.S.A.
Posts: 1,127
parts

LadyButler:
The following is Rheem's website. Towards the left of the screen type in your zipcode and it will show you names and phone numbers of contractors. They may (or may not) want to sell you this part...but it's worth a try.
http://www.rheemac.com/

If I was in need of this switch, I'd contact my HVAC parts provider, a company by the name of Johnstone Supply. They have branches all over the country. Here is their website:
http://www.johnstonesupply.com/corp/Default.aspx
type in your state and zipcode and will show you the local Johnstone store. They don's sell retail and require that one open an account...they may or may not sell it to you directly...again, it's worth the try.

What are you ordering?
Part Name (as per Rheem): Overtemperature switch
[a.k.a. rollout]
Rheem's part number: 47-22383-11
Appliance: Rheem Furnace
Type of Fuel it burns: Natural Gas
Furnace's M/N: RGDA-075C-ER [as per your posting]
Type of ignition: Standing Pilot


BTW, I was a bit on the low side with my recommendation of a high-limit setpoint of 150F, A dirty filter could have the temperatures in the plenum easily reach that...a setting of about 200F would work better (Honeywell recommends this).

Did you find the fan-limit switch (part#25) ?
What are the current settings?
 
  #54  
Old 01-16-08, 06:46 PM
LadyButler's Avatar
Member
Thread Starter
Join Date: Jan 2008
Posts: 28
There are three pointers (their wording) on my dial. 75, 125 and just under 200, as best as I can tell. I tried to snap a picture... but it's not clear enough to read.
 
  #55  
Old 01-16-08, 10:29 PM
LadyButler's Avatar
Member
Thread Starter
Join Date: Jan 2008
Posts: 28
Ideally, someone (you or your husband) would have to babysit this furnace (remove the service door and sit patiently in front of it), so hopefully the problem occurs while mounting guard in front of it.
I did it. It only took about two minutes. There was nothing that even flickered out of place when the button randomly popped up and shut off the burners...*insert sad music here*... leaving the lonely pilot light to fend for itself.

I've found a few places on the internet that will sell the switch new in package. I realize Rheem doesn't cover parts that aren't sold to qualified HVAC folks- but this baby was built in 1988... so I don't know that it really matters. Thoughts?
 
  #56  
Old 01-17-08, 12:00 AM
Member
Join Date: Jan 2008
Posts: 12
Roll-out switch

You most likely have hairline cracks in the heat exchanger and may not even be visible with a scope if expansion only happens when heated.
The switch may very well be bad now because they're not made to cycle so much.
Put a stem thermostat near where the roll-out was and see if the temp. is actually getting that hot.
Not highly recommended, but heat water just below and above temp rating of roll-out and touch surface of water with it.
Dry quickly and don't submerge.

Your heat exchanger may have a 20 year warrenty.
Labor should be quoted around 3 hours.

I recommend upgrading any old inefficent problamatic furnace.
 
  #57  
Old 01-17-08, 01:32 AM
pflor's Avatar
Member
Join Date: Dec 2007
Location: U.S.A.
Posts: 1,127
It's good news that the flame is not rolling out.
It's not so good news but hcfcr22 is likely right about hairline cracks in your heat exchanger...That switch may be tripping not b/c of a rollout but rather b/c of being too hot (for the switch's taste) around where it is installed. In other words, there is now a higher temperature around where the switch is installed than what the switch was made for and used to. And as rcfcr22 suggests, that switch may be bad by now. Wy is this happening??? two-word answer: OLD AGE.

If the heat exchanger warranty is 20 years, that unit might be just shy of being 20 years old, so probably not too much luck there.

A thermometer like the one hcfcr22 is talking about could be the ones used around the kitchen to measure the temperature of chicken/turkey by poking them...

Let's see if we can at least get you thru the winter. Perhaps if we increase the airflow thru the furnace [I mean, the air in the ducts that goes to the rooms in your house], we may prevent this tripping from happening again. though the switch nevertheless may have to be replaced b/c its behavior could be erratic in the future...nuisance tripping for no good reason

Please do the following 3-part test with the service door of the furnace removed on parts 1&2, just so the switch does not trip on us while you're performing the test, AND, please also raise high the setpoint from the t-stat to, say, 85F, just so the t-stat does not turn the furnace OFF while you're at this:

(1) insert the shaft of that stem thermometer hcfcr22 is suggesting INTO anyone of the SUPPLY registers in your home (the ones that blow hot air into the rooms)...wait until the temperature marker stops moving...read the temperature and take note of it. Keep the thermometer at that spot (do not remove)

.....If the air temperature is higher than 115-to-120F, let's increase the airflow...

(2) TEMPORARILY, from the thermostat, flip the switch that reads FAN from the AUTO to the ON position [you will feel a marked increase in the airflow thru the house as the fan is now working on its summer mode]. Wait another 2 minutes or so [until the needdle in the thermometer stops moving]...take note of the temperature the thermometer is reading now.

(3) Keep the furnace running like this but go and put back the service door...let the unit run for another good 5-10 minutes or so let's hope the switch won't trip again.
[your house must be getting way too warm by now] .

If the switch did not trip, we're ready to change the speed of the fan. Switch the thermostat to OFF and the FAN switch back to AUTO.

The blower in your furnace is a 3-speed blower. From factory came set to run at high speed in the summer and low speed in the winter. We're going to switch that winter speed from "low" to "medium".
This will be worthwhile trying ONLY if the rollout did not trip at any time during the 3-part test above.

I'll wait for your feedback before proceeding.
 
  #58  
Old 01-17-08, 01:49 AM
pflor's Avatar
Member
Join Date: Dec 2007
Location: U.S.A.
Posts: 1,127
recommendation on posting#56

Please also take the time to perform the two tests hcfcr22 is recommending...it's a very good recommendation. These tests will help determine if all that is happening here is "hopefully" just b/c that rollout went nuts and needs to be sent to the mad house and be exchanged for a new one...YES buy a new one [on posting#55 you asked for an opinion if you should go ahead and buy it...they are cheap].
 

Last edited by pflor; 01-17-08 at 02:28 AM.
  #59  
Old 01-17-08, 01:57 AM
pflor's Avatar
Member
Join Date: Dec 2007
Location: U.S.A.
Posts: 1,127
pointers in fan-limit switch

In posting#54 you reported the position of the 3 pointers: 75F, 125F and 200F.

Please move the middle pointer (the one set to 125F) down to 100F.

I'll tell you why later.
 
  #60  
Old 01-17-08, 02:26 PM
Member
Join Date: Jan 2008
Location: northern panhandle of W.V.
Posts: 8
coleman furnace

I have a 10 year old coleman evcon. I replace the transformer,flame detector,controler and fuel nozzle. I set the gaps on the electrodes, but I need the setting for the nozzle deapth and how to adjust the air mixture. When the burner is on it is fluttering. Any help would be great.
 

Last edited by grubby; 01-17-08 at 02:29 PM. Reason: miss spelled a word
  #61  
Old 11-30-08, 01:43 PM
Member
Join Date: Nov 2008
Posts: 1
mr leo

I have a gas heater RGDA-075c-ER. Some how the fan-blower does not stop for a long time when the burner shuts off
Anybody can help me?
 
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