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danielr 09-21-2009 09:57 PM

Pilot burner replacement - Carrier 58GS150-CB furnace
I'm replacing the pilot burner (part # LH 680 005) for a Carrier 58GS150-CB furnace. The installation looks simple enough except for the gas supply tube for the pilot. On the pilot burner there is a threaded brass fitting with a taper that fits into a taper on the orfice. How much do I tighten this brass nut? Can I reuse the existing tube from the gas valve? Any info would be greatly appreciated. Thank you.

beenthere 09-22-2009 03:56 AM

Run new tubing.
Tighten until ferrel breaks free. And nut tightens.

Then leak check it.

hvaclover 09-22-2009 06:50 AM

If that existing pilot tubing is serviceable (not messed up) it can be reused.

Make sure the connection are gas tight with a liquid soap solution.

danielr 09-22-2009 09:14 PM

Thank you for the advice
Thank you hvaclover and beenthere for the replies. I would have never guessed that the ferrule breaks free and can now see where it's scored. You've saved me some head scratching. I'll check the connections for leaks as advised. Thanks again.


danielr 09-24-2009 01:08 AM

Update - Pilot Burner problem persists - Help!
I spoke too soon in thinking the repair would be easy. I've replaced the pilot burner on my Carrier 58GS150-CB but the same problem persists. The part # is LH 680 005 which replaces the original 535-740A. The part is identical to what was in the furnace and a genuine Carrier part.

I replaced the pilot burner because the gas valve would chatter particulary after the pilot burner was warm. The sequence would be as follows:

Call for heat
Gas valve chatters (large direct acting solenoid)
Ignitor and Pilot turn on
Pilot burner heats
Gas valve chatters (small pilot solenoid - sometimes both)
Gas turns on

The cycle is always successful but the chattering is both loud and disturbing. Sometimes lasting 2-3 seconds.

I made the determination it was the pilot burner by disconnecting it and manually duplicating its function with clip leads. Connecting YEL to BRN (GRN on pilot burner harness) turns on the ignitor and pilot. Switching to YEL to WHT turns on the gas to the burners. No chatter when I operate it this way. Can the new pilot burner also be flaky or am I missing something?

I've even tried a large isolated variable tranformer for the 24V supply in case that was an issue. Any ideas would be appreciated before I invest in another pilot burner.

Thank you,

hvaclover 09-24-2009 07:43 AM

That valve needs replacing. They can be tricky to check accurately.

There is a small solenoid that is energized first called a PICK AND HOLD coil.
It is dropping out the main valve, That's where tha growling and chatter is coming from.

Now I have not read the whole thread, but you did check for 24 volts is constant to valve did you not?

The valve is refereed to as a "FIVE WIRE VALVE" in my circles. Real pain. My own furnace has one.
EF32CW183 Bryant / Carrier / Payne Gas Valve
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Bryant/Carrier/Payne 5 wire gas valve.

danielr 09-24-2009 11:41 AM

Checked 24Vac supply
I did check the 24Vac to the valve and substituted a larger variable transformer set at 30Vac. Also cleaned all the wiring contacts.

What I can't get past is with two switches replicating the function of the safety pilot, no chatter. The gas valve must be sensitive to the nuances or hysterisis in the actual sensor. I tried to replicate the function in that the pilot and ignitor contact opens before the call for gas closes.

One other item that bothers me that may shed some light is the operation of the ignitor. From the schematic it seems it should only fire as long as the safety pilot contact (YEL and GRN wires) remain closed. These open as the pilot flame heats the sensor but the ignitor continues to fire. It does so until the other contacts on the safety pilot close (YEL and WHT) and actual gas flows to the burners. I don't see how this function is latched or whether is should be. Worth mentioning also is the firing rate of the ignitor slows as the tip heats heats up. Perhaps a future problem?

It looks like I'm on the path of replacing the valve but wish the testing was more conclusive. Thank you again for your help.

hvaclover 09-24-2009 03:06 PM

All those questions are great stuff to know, but they won't get your furnace fixed any faster. I can only tell you that what you have is a bum valve.

As a junior tech I probably would have been interested in the details that you present, but as a practical matter I have to get a furnace up and running asap. My trouble shooting techniques have evolved to the most abbreviated
point that gets the job done with out misdiagnosing the problem as a result.

My point is when you have been doing this work so long servicing becomes intuitive and all those technical details you ask are no longer important to the job.

A rookie, needs to know that stuff because his skill set is still maturing.

What caused your transformer to blow?

danielr 09-24-2009 05:10 PM

The transformer didn't blow, I just wanted to rule it out by substituting something that couldn't be dragged around by the load. It didn't make any difference.

I'll pick up a gas valve tomorrow. My questioning is based on me wanting to understand the details as you noted. I must say I know more about 80's vintage furnaces than a few days ago! Your advice is much appreciated.

hvaclover 09-24-2009 05:45 PM


Originally Posted by danielr (Post 332030)
The transformer didn't blow, I just wanted to rule it out by substituting something that couldn't be dragged around by the load. It didn't make any difference.

I'll pick up a gas valve tomorrow. My questioning is based on me wanting to understand the details as you noted. I must say I know more about 80's vintage furnaces than a few days ago! Your advice is much appreciated.

You'll go nuts on the current models. Less than three feet tall and the parts are so small you need Herve Villachez (Tatu off Fantasy Island) to get at them. 5lbs of doo doo in a 1 lb bag:mad:.

i had to revise my entire trouble shooting procedure to get the job done as fast as I used to on the old ones.

Kaystar5 02-08-2013 07:24 AM

Hi, Can you help me? I have the same situation as posted above(58s Carrier).but both pilot burner and gas vavle have been replaced. Pilot burner was fine until new gas valve. Now chattering and short cycling happens. Repair tech says it is the pilot burner. Your posts suggest it's the solenoid on the gas valve.Am going to replace brand new pilot burner to try to correct or should I ask that gas valve be replaced?Thanks.

old_squid 02-08-2013 12:19 PM

The size of the pilot flame is sometimes to blame for gas valve chatter on these units. The flame should be clean and sharp in apprearance almost like a minture blow torch. The tips should not be lazily floating. These pilot assemblies rely on heat to warp a switch inside of them to make a pair of contacts switch positions to control the lighting process. They can "hover or quickly cycle" and possibly produce the noise you're getting from the valve. Inside, the warp switch needs to close one set while opening the other. A good pilot flame heats this warp switch up so fast that this "change" happens so fast you only hear the one click of the valve transitioning.

I will assume that the new pilot assembly came with and was installed with the correct pilot orfice that you need for the gas you're burning (either LP or Natural).

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