How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Mark Henley Your Own Question

Mark Henley
Mark Henley, Journeyman Technician
Category: HVAC
Satisfied Customers: 3217
Experience:  UA Journeyman Pipefitter , HVAC, Refrigeration, DDC controls. 26 years.Commercial & residential
10307865
Type Your HVAC Question Here...
Mark Henley is online now
A new question is answered every 9 seconds

My furnace is making a knocking noise. It does not happen all

Customer Question

My furnace is making a knocking noise. It does not happen all the time, but it is happening more regularly. There is also a slight gas odor sometimes. The noise appears to be from the flames pulsing after they are initially lit. My gas valve is the WHITE-RODGERS 36g24 type 205 GAS VALVE. I have include 2 images of the furnace and a short video of the issue happening here...

http://tinypic.com/2mpkqujt

Is this dangerous? What can be causing this? How much should it cost to have it fixed?
Thank you.
Submitted: 5 years ago.
Category: HVAC
Expert:  Mark Henley replied 5 years ago.

Hi,

 

Thanks for the visuals,

 

Can you put your hand on the gas valve while this is doing it and tell me if you can feel the valve pulsing in tune with the flames ?

 

Let me know,

 

Thanks

 

Mark

Customer: replied 5 years ago.
Ok - I did. And - yes, it does pulsate with the flames.
Expert:  Mark Henley replied 5 years ago.

Hi,

 

You really need to have the gas pressure checked before the appliance and while its running but its a pretty good bet that this valve has water in it or some other type of debris. I see you do have a drip leg at the furnace in the gas line I would take that apart and see if you get anything out of there as far as crud or if you can see water trails. I think you are going to have to start with replacing the gas valve if you don't have any means of checking the pressures.

 

The gas smell is probbaly from the vlave also.

 

To have the valve replaced will probably cost you about 300 dollars.

 

Thanks

 

Mark

 

 

Customer: replied 5 years ago.
Yeah, it happened the beginning of last year and then the last 2 months of winter it stopped completely.

I was hoping it would do the same this year. Could it be an obstruction in the exhaust pipe or something?
Expert:  Mark Henley replied 5 years ago.

Hi,

 

Shouldn't be, the pressure switch should detect a blockage and kill the gas valve if the vent was blocked, that's why I figure the pressure isn't changing much in the exchanger and whatever it is would have to on the incoming side of the exchanger.

 

Thanks

 

Mark

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • You did one super job of explaining to me everything there is to know about this fridge. I'm looking forward to asking you questions in the future. Jimmy Bagley, IA
< Last | Next >
  • You did one super job of explaining to me everything there is to know about this fridge. I'm looking forward to asking you questions in the future. Jimmy Bagley, IA
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY
  • Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know. Robin Elkton, Maryland
 
 
 

Meet The Experts:

 
 
 
  • gotoman for ac

    HVAC Technician

    Satisfied Customers:

    4657
    51 years of experience install design and repair of all makes and models of AC
< Last | Next >
  • http://ww2.justanswer.com/uploads/SE/ServiceTechRus/2012-6-7_2119_056.64x64.JPG gotoman for ac's Avatar

    gotoman for ac

    HVAC Technician

    Satisfied Customers:

    4657
    51 years of experience install design and repair of all makes and models of AC
  • http://ww2.justanswer.com/uploads/AL/alumalite/2012-5-10_234018_shutterstock506249951forJA500.64x64.jpg Phil's Avatar

    Phil

    Mechanical Engineer

    Satisfied Customers:

    3888
    Retired HVAC/ Electrical & Boiler contractor. Industrial
  • http://ww2.justanswer.com/uploads/skibum0101/2008-12-16_015819_just_answer.jpg Rick Mather's Avatar

    Rick Mather

    HVAC Technician

    Satisfied Customers:

    3132
    35 years experience, HVAC
  • http://ww2.justanswer.com/uploads/RY/Rygis20/2011-5-7_3143_DSC5324.64x64.JPG Matthew's Avatar

    Matthew

    HVAC Technician

    Satisfied Customers:

    1994
    14 years experience in the HVAC field of service, installation, Manual J & D calculations
  • http://ww2.justanswer.com/uploads/KE/kentguidry/2011-9-26_214316_0059.64x64.jpg Kenton Guidry's Avatar

    Kenton Guidry

    HVAC Technician

    Satisfied Customers:

    962
    12 years install/service experience.
  • http://ww2.justanswer.com/uploads/solarman1947/2009-12-13_223915_phpkKBcXq_c2PM.jpg Rick Ridley's Avatar

    Rick Ridley

    UK Heating Engineer

    Satisfied Customers:

    871
    Retired But have had 30 years on the tools, Ex CORGI
  • http://ww2.justanswer.com/uploads/Ironheadfan/2009-12-18_222416_pump_005.jpg Tom's Avatar

    Tom

    HVAC Technician

    Satisfied Customers:

    770
    16+yrs HVAC/R service. Residential Commerical Industrial
 
 
 
Chat Now With A HVAC Technician
Mark Henley
Mark Henley
HVAC Controls DDC
3214 Satisfied Customers
UA Journeyman Pipefitter , HVAC, Refrigeration, DDC controls. 26 years.Commercial & residential