FHB Logo Facebook LinkedIn Email Pinterest Twitter X Instagram Tiktok YouTube Plus Icon Close Icon Navigation Search Icon Navigation Search Icon Arrow Down Icon Video Guide Icon Article Guide Icon Modal Close Icon Guide Search Icon Skip to content
Subscribe
Log In
  • How-To
  • Design
  • Tools & Materials
  • Restoration
  • Videos
  • Blogs
  • Forum
  • Magazine
  • Members
  • FHB House
  • Podcast
Log In

Discussion Forum

Discussion Forum

Carrier furnace problems

| Posted in Energy, Heating & Insulation on February 13, 2004 06:01am

Anyone have any thoughts regarding a problem I’m having with my Carrier Weathermaker SX furnace? It seems to run normally for the most part, except when it runs for 2 hours straight or so. Like when I get home in the evening and turn it up after it has been turned down all day. After running for a long period of time, it seems to have difficulty starting again after the thermostat shuts it down when the house finally warms up. Here’s what I’ve found. The thermostat is calling for heat. The induced draft blower motor comes on, the pilot flame ignites fine and stays lit. Then the gas valve clicks/thunks but the burner does not light. Gas valve thunks again (I assume shuts off) and waits several seconds and then repeats the cycle. Eventually, the burner will light. If not, I can shut the furnace off for a few minutes and then turn it back on and every thing works fine. It appears to me that the gas valve is not confirming all conditions necessary to allow the burner to light and is then shutting off the gas after a few seconds. The burner is not igniting even for a short time. Only the pilot flame lights and it seems to work fine. I cleaned out the burner, intake and exhaust as they had some deposits of Asian lady beetles. Also the condensate drain appeared to be gunked up so I blew it out and it now appears to be clear. The furnace was installed new in 1991. It is model 58SXA080-GG, series 100 and has been converted to propane fuel. Is this furnace known for any particular weak areas? Any comments or thoughts would be appreciated.

It ain’t pretty fer nice, but it’s hell fer strong.

Reply
  • X
  • facebook
  • linkedin
  • pinterest
  • email
  • add to favorites Log in or Sign up to save your favorite articles

Replies

  1. gtmtnbiker | Feb 13, 2004 06:10am | #1

    I had a similar problem recently with my York Diamond 80 furnace.  It has electronic ignition (no pilot light) and would light up the flame ok. But a few second laters, the gas valve would shut off. It would repeat the cycle a few more times.  The furnace guy diagnosed the problem with the flame sensor.  This is a sensor near the flames that is supposed to generate millivolt current to keep the gas valve open.  In my case, there was some dust on it thereby causing a weak current where it would sometimes work and sometimes not. 

    The repair man showed me how to read the diagnostic code on the furnace.  There's a small port hole where you can see a blinking LED light.  The number of blinks will correspond to a trouble code.  This sort of information can also be found in your owner/service manual if you can locate it.

  2. rich1 | Feb 13, 2004 08:23am | #2

    Without being able to put my meters on it , I would guess that the pilot assembly is getting weak.You have a bi-metal pilot safety that has to heat up before the main gas valve can open.

    1. DonMarty | Feb 14, 2004 04:54am | #4

      I think that you're probably right. It has a pilot flame sensing switch. I thought that the pilot would go out if the sensing switch failed and that's not happening, but I could be wrong. The furnace is 12 years old so it certainly wouldn't hurt to replace the ignitor-flame sensing switch assembly as a start. Thanks for your help.It ain't pretty fer nice, but it's hell fer strong.

  3. User avater
    goldhiller | Feb 13, 2004 06:19pm | #3

    I'm not familiar with this particular furnace but looked round a bit and can't find any specific info abut what type of pilot flame proving device you might have. It might be a readily available simple thermocouple that needs replacing, but whatever type of sensing device you have it sure sounds like that's what is most likely at fault here. It would be the cheapest place to start if you don't have the specs for your unit and/or a meter capable of reading current in the ranges delivered by these proving devices to confirm faulty performance.

    Since I don't have the specifics on your furnace, it just might be that it's a Honeywell gas valve with a flame rod sensor ignition like GT described. There would be a small hot surface igniter which is responsible for igniting and establishing a pilot flame which must then prove itself to the main gas valve before ignition of the main burners is allowed. If so, then you would have a device that looks like the pic on the bottom of this page involved in the pilot ignition.

    http://www.pdqsupplyinc.com/oemheating/heilquaker/quakerpages/flamesen.htm

    There would be a pair of wires from this little unit that plug into the Honeywell valve control.

    If this is so, then it might well be time for a new ignition module. Not very expensive (around $20 at most any HVAC place) and fairly easy to put in.

    A couple of cautions here. Handle the thing with the greatest of care. Don't bump or handle the hot surface igniter itself or the flame rod sensor. The hot surface metal is very brittle and so breaks without any real provocation and if you touch the flame rod and don't clean it again, you've likely just substantially shortened it's life expectancy.

    As most control units do these days, yours needs a good bonding wire connection to ground. While you're in there, make sure this connection is clean and sound.

    Turn the power off to the furnace while you work in there.

    FWIW, the term "flame rod sensor" here is really a misnomer. That rod doesn't actually sense flame at all but rather delivers current to the top of the established pilot flame. It's the flame itself that transforms and acts as a conductor for the AC current delivered into the top of the flame. The resulting current at the base of the pilot flame then arrives in DC milliamps. It's this current that the control valve senses and then subsequently allows the valve to the main burners to open. Therefore the metal at the base of the pilot flame must also be clean for conduction purposes and the size of the pilot must be adequate for allowing sufficient conduction of that current.

    Knowledge is power, but only if applied in a timely fashion.

    Edited 2/13/2004 10:34:20 AM ET by GOLDHILLER



    Edited 2/13/2004 11:53:08 AM ET by GOLDHILLER

    1. DonMarty | Feb 14, 2004 04:57am | #5

      It actually has a bi-metalic flame sensing switch rather than a rod. I think that I'll replace it as a start and go from there.

      Thanks for your help.It ain't pretty fer nice, but it's hell fer strong.

  4. WorkshopJon | Feb 14, 2004 06:59am | #6

    Dmarty,

    Had a similar problem with my current furnace when first installed.  It was caused by a build-up of moisture in the horizontal exhaust vent tube. Just enough to create a high enough pressure to kick the unit off upon restart. It was not plumbed arrow straight, and formed a sort of trap, thus restricting flow.

    Is yours a high efficiency, ie. vented out the side of your house with PVC?

    Jon

    1. DonMarty | Feb 14, 2004 05:19pm | #7

      The condensate drain was what I first suspected. That would explain why it runs fine at first but not after a few hours of use. The water is not draining as well as it should and is backing up. I'll check it again. As I said before though, it wouldn't hurt to replace the pilot switch considering the age of the furnace, so I'll do that too. Thanks for the info.It ain't pretty fer nice, but it's hell fer strong.

Log in or create an account to post a comment.

Sign up Log in

Become a member and get full access to FineHomebuilding.com

Video Shorts

Categories

  • Business
  • Code Questions
  • Construction Techniques
  • Energy, Heating & Insulation
  • General Discussion
  • Help/Work Wanted
  • Photo Gallery
  • Reader Classified
  • Tools for Home Building

Discussion Forum

Recent Posts and Replies

  • |
  • |
  • |
  • |
  • |
  • |
View More Create Post

Up Next

Video Shorts

Featured Story

Simple and Discreet Countertop Power

A new code-compliant, spill-safe outlet from Legrand offers a sleek solution for a kitchen island plug.

Featured Video

How to Install Cable Rail Around Wood-Post Corners

Use these tips to keep cables tight and straight for a professional-looking deck-railing job.

Related Stories

  • Fire-Resistant Landscaping and Home Design Details
  • A New Approach to Foundations
  • A Closer Look at Smart Water-Leak Detection Systems
  • Guest Suite With a Garden House

Highlights

Fine Homebuilding All Access
Fine Homebuilding Podcast
Tool Tech
Plus, get an extra 20% off with code GIFT20

"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Fine Homebuilding Magazine

  • Issue 332 - July 2025
    • Custom Built-ins With Job-Site Tools
    • Fight House Fires Through Design
    • Making the Move to Multifamily
  • Issue 331 - June 2025
    • A More Resilient Roof
    • Tool Test: You Need a Drywall Sander
    • Ducted vs. Ductless Heat Pumps
  • Issue 330 - April/May 2025
    • Deck Details for Durability
    • FAQs on HPWHs
    • 10 Tips for a Long-Lasting Paint Job
  • Issue 329 - Feb/Mar 2025
    • Smart Foundation for a Small Addition
    • A Kominka Comes West
    • Making Small Kitchens Work
  • Issue 328 - Dec/Jan 2024
    • How a Pro Replaces Columns
    • Passive House 3.0
    • Tool Test: Compact Line Lasers

Fine Home Building

Newsletter Sign-up

  • Fine Homebuilding

    Home building tips, offers, and expert advice in your inbox.

  • Green Building Advisor

    Building science and energy efficiency advice, plus special offers, in your inbox.

  • Old House Journal

    Repair, renovation, and restoration tips, plus special offers, in your inbox.

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters

Follow

  • Fine Homebuilding

    Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.

    Start Free Trial Now
    • Facebook
    • Instagram
    • X
    • LinkedIn
  • GBA Prime

    Get instant access to the latest developments in green building, research, and reports from the field.

    Start Free Trial Now
    • Facebook
    • YouTube
  • Old House Journal

    Learn how to restore, repair, update, and decorate your home.

    Subscribe Now
    • Facebook
    • Instagram
    • X
  • Fine Homebuilding

    Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.

    Start Free Trial Now
    • Facebook
    • Instagram
    • X
    • LinkedIn
  • GBA Prime

    Get instant access to the latest developments in green building, research, and reports from the field.

    Start Free Trial Now
    • Facebook
    • YouTube
  • Old House Journal

    Learn how to restore, repair, update, and decorate your home.

    Subscribe Now
    • Facebook
    • Instagram
    • X

Membership & Magazine

  • Online Archive
  • Start Free Trial
  • Magazine Subscription
  • Magazine Renewal
  • Gift a Subscription
  • Customer Support
  • Privacy Preferences
  • About
  • Contact
  • Advertise
  • Careers
  • Terms of Use
  • Site Map
  • Do not sell or share my information
  • Privacy Policy
  • Accessibility
  • California Privacy Rights

© 2025 Active Interest Media. All rights reserved.

Fine Homebuilding receives a commission for items purchased through links on this site, including Amazon Associates and other affiliate advertising programs.

  • Home Group
  • Antique Trader
  • Arts & Crafts Homes
  • Bank Note Reporter
  • Cabin Life
  • Cuisine at Home
  • Fine Gardening
  • Fine Woodworking
  • Green Building Advisor
  • Garden Gate
  • Horticulture
  • Keep Craft Alive
  • Log Home Living
  • Military Trader/Vehicles
  • Numismatic News
  • Numismaster
  • Old Cars Weekly
  • Old House Journal
  • Period Homes
  • Popular Woodworking
  • Script
  • ShopNotes
  • Sports Collectors Digest
  • Threads
  • Timber Home Living
  • Traditional Building
  • Woodsmith
  • World Coin News
  • Writer's Digest
Active Interest Media logo
X
X
This is a dialog window which overlays the main content of the page. The modal window is a 'site map' of the most critical areas of the site. Pressing the Escape (ESC) button will close the modal and bring you back to where you were on the page.

Main Menu

  • How-To
  • Design
  • Tools & Materials
  • Video
  • Blogs
  • Forum
  • Project Guides
  • Reader Projects
  • Magazine
  • Members
  • FHB House

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Popular Topics

  • Kitchens
  • Business
  • Bedrooms
  • Roofs
  • Architecture and Design
  • Green Building
  • Decks
  • Framing
  • Safety
  • Remodeling
  • Bathrooms
  • Windows
  • Tilework
  • Ceilings
  • HVAC

Magazine

  • Current Issue
  • Past Issues
  • Magazine Index
  • Subscribe
  • Online Archive
  • Author Guidelines

All Access

  • Member Home
  • Start Free Trial
  • Gift Membership

Online Learning

  • Courses
  • Project Guides
  • Reader Projects
  • Podcast

More

  • FHB Ambassadors
  • FHB House
  • Customer Support

Account

  • Log In
  • Join

Newsletter

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Follow

  • X
  • YouTube
  • instagram
  • facebook
  • pinterest
  • Tiktok

Join All Access

Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features.

Start Your Free Trial

Subscribe

FHB Magazine

Start your subscription today and save up to 70%

Subscribe

Enjoy unlimited access to Fine Homebuilding. Join Now

Already a member? Log in

We hope you’ve enjoyed your free articles. To keep reading, become a member today.

Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine.

Start your FREE trial

Already a member? Log in

Privacy Policy Update

We use cookies, pixels, script and other tracking technologies to analyze and improve our service, to improve and personalize content, and for advertising to you. We also share information about your use of our site with third-party social media, advertising and analytics partners. You can view our Privacy Policy here and our Terms of Use here.

Cookies

Analytics

These cookies help us track site metrics to improve our sites and provide a better user experience.

Advertising/Social Media

These cookies are used to serve advertisements aligned with your interests.

Essential

These cookies are required to provide basic functions like page navigation and access to secure areas of the website.

Delete My Data

Delete all cookies and associated data