HVAC

Have HVAC Questions? Ask an HVAC Expert for Answers

Ask an Expert,
Get an Answer ASAP!

HVAC

I have a Heil natural gas furnance; model # *****; the

Customer Question
exhaust blower continues to run...
I have a Heil natural gas furnance; model # *****; the exhaust blower continues to run and the furnace will not light, we just replaced the main limit switch and it still does will not light.
Submitted: 4 years ago.Category: HVAC
Show More
Show Less
Ask Your Own HVAC Question
Answered in 4 minutes by:
2/26/2013
HVAC Technician: Tim H., HVAC Professional replied 4 years ago
Tim H.
Tim H., HVAC Professional
Category: HVAC
Satisfied Customers: 3,971
Experience: Experienced in all aspects of HVAC, both residential and commercial.
Verified
Please do not rate me until we have had a chance to work through a solution. This may take a while. Do not use the ratings to rate the site, just the technician you are working with. For site issues, contact customer service.
In most cases, if the main blower continues to run and furnace will not light it indicates an open limit switch. It can be the pri***** *****mit (which is probably the one you replaced), or a flame rollout or even certain other types of limit switches on some furnaces such as a draft safeguard or secondary limit. Usually this will be evident as a LED flash code from the main board indicating an open limit switch.
Ask Your Own HVAC Question
Customer reply replied 4 years ago
The unit seems to be in constant purge, because the exhaust blower continues to run
HVAC Technician: Tim H., HVAC Professional replied 4 years ago
What kind of flash code are you getting at the board? Have you checked intake and exhaust PVC pipes for blockage?
Ask Your Own HVAC Question
Customer reply replied 4 years ago
yes, did not see any blockage in PVC pipes, did not see any flashing flash codes
HVAC Technician: Tim H., HVAC Professional replied 4 years ago
If the inducer continues to run and burners don't light, you have one of the following conditions:
1) a plugged intake or exhaust (this can be as small as a leaf that got sucked inside one of the pipes-may not be visible
2) a disconnected or kinked pressure switch hose
3) a condensate drainage system that is plugged
4) a slow or defective inducer motor
5) a bad pressure switch
Ask Your Own HVAC Question
Customer reply replied 4 years ago
we will try replacing the pressure switch tomorrow, if we do not freeze tonight!! :-)
HVAC Technician: Tim H., HVAC Professional replied 4 years ago
I would try removing the intake pipe from the top of the furnace OR leave the top door open or off and see if this makes a difference. It may be as simple as something that got sucked into the intake pipe.
Ask Your Own HVAC Question
Customer reply replied 4 years ago
ok, we will try that first.
HVAC Technician: Tim H., HVAC Professional replied 4 years ago
If that doesn't work, check some of the other things on that list before ordering parts.
Ask Your Own HVAC Question
HVAC Technician: V12Tech, HVAC Technician replied 4 years ago
V12Tech
V12Tech, HVAC Technician
Category: HVAC
Satisfied Customers: 260
Experience: A.A.S. MET, E.P.A cert, Certificate of Excellence HVAC/R
Verified
http://www.managemylife.com/mmh/lis_pdf/INSTL/L0803197.pdf
http://www.managemylife.com/mmh/owner_manuals/7671/ICP-Furnace-Heater-Gas-L0803197
Heil and Tempstar Furnace Eyelet Failures
Models NUGM, NTGM, NDGM, NCGM with date codes of L9421 through L9723.
These furnaces were subject to premature heat exchanger failure and were thus the subject of a service bulletin due to eyelet failures.
If you own one of these furnaces,they suggest seeking a heating contractor for possible repairs or replacement .
Have the exchanger checked where the exchanger is pinched together with rings. These models had issues.
If the unit was not exhibiting a code that also leads me to suspect the board is bad, this original timer board and replacement both have a diagnostic LED/light.
Ask Your Own HVAC Question
HVAC Technician: Tim H., HVAC Professional replied 4 years ago
The heat exchanger issue has nothing to do with your problem. You are experiencing an issue with the inducer motor continuing to run. This could be for one of the reasons I have previously mentioned or could even be from a stuck relay on the board. We have not determined that as of yet.
Ask Your Own HVAC Question
HVAC Technician: Tim H., HVAC Professional replied 4 years ago
If you are truly not getting a LED flash code (and I'd want to make sure you know where to look for this), then it would tend to be more likely a board issue.
Ask Your Own HVAC Question
HVAC Technician: V12Tech, HVAC Technician replied 4 years ago
The pressure switch not closing or staying closed etc will be a fault which should lock it out if normal was my point, which it is not doing, the inducer motor will not run unless a limits open, ala exchanger issue relevance or bad board as earlier stated, the lack of a lock out and diagnostic precluded the other possibilities in my estimation, after 3-5 attempts the control should have locked out and faulted exhibiting a code
Ask Your Own HVAC Question
HVAC Technician: Tim H., HVAC Professional replied 4 years ago
The board could possibly be bad, but I doubt the heat exchanger is although it's never a bad idea to have your heat exchanger checked out annually. The furnace has a protection device called a flame rollout switch which would trip if the heat exchanger had a hole or defect in it. I want to be si=ure that you are looking in the right place for the LED flash code. This will show up after the furnace has attempted to start. The one way to check for a bad board is to remove the heat signal from the board by turning the heat all the way down or off. With no signal at C-W at the board, the inducer should stop unless the small relay on the board is bad allowing it to run non stop.
Ask Your Own HVAC Question
HVAC Technician: V12Tech, HVAC Technician replied 4 years ago
With a recall whether the exchangers bad or not is immaterial,I would insure this unit is not under recall before putting any money into this troubled design,If it is not from this serial code era, I would recommend Co detectors in addition as the model was troubled.
Ask Your Own HVAC Question
HVAC Technician: Tim H., HVAC Professional replied 4 years ago
The easiest way to determine if you have a board problem is to take away the call for heat. You can do this by either turning down the heat to well below room temperature or turning the thermostat "system" switch to off. Then go down to your furnace and see if the inducer is still running. If it is, replace the board, if not-we can go on with the troubleshooting. Sometimes other experts become involved in our questions whether we want them to or not. To determine who you'd like to continue to work with, compare his number of accepts and rating to mine and make that decision.
As I said previously, it is always good practise to have your furnace inspected annually by a qualified HVAC contractor.
Ask Your Own HVAC Question
Ask Tim H. Your Own Question
Tim H.
Tim H.
Tim H., HVAC Professional
Category: HVAC
Satisfied Customers: 3,971
3,971 Satisfied Customers
Experience: Experienced in all aspects of HVAC, both residential and commercial.

Tim H. is online now

A new question is answered every 9 seconds

How JustAnswer works:

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

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.

JimmyBagley, 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!!!!

AlexLos 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.

GPHesperia, CA

I couldn't be more satisfied! This is the site I will always come to when I need a second opinion.

JustinKernersville, 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.

EstherWoodstock, 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.

RobinElkton, Maryland

< Previous | Next >

Meet the Experts:

Phil

Phil

Mechanical Engineer

6,877 satisfied customers

Retired HVAC/ Electrical & Boiler contractor. Industrial

Rick Mather

Rick Mather

HVAC Technician

3,133 satisfied customers

35 years experience, HVAC

Matthew

Matthew

HVAC Technician

2,014 satisfied customers

14 years experience in the HVAC field of service, installation, Manual J & D calculations

Kenton Guidry

Kenton Guidry

HVAC Technician

963 satisfied customers

12 years install/service experience.

Brian HVAC Guy

Brian HVAC Guy

HVAC Technician

953 satisfied customers

I have been an HVAC/R mechanic/technician for 30+ years.

Rick Ridley

Rick Ridley

UK Heating Engineer

871 satisfied customers

Retired But have had 30 years on the tools, Ex CORGI

Tom

Tom

HVAC Technician

770 satisfied customers

16+yrs HVAC/R service. Residential Commerical Industrial

< Previous | Next >

Related HVAC Questions
I have a 5 year old Tempstar furnace and it's short cycling.
I have a 5 year old Tempstar furnace and it's short cycling. Meaning the furnace fires, runs for a period of time with heat coming out, however shuts off before getting to the desired temperature. as … read more
HVAC Guru
HVAC Guru
Service Technician
Associate Degree
682 satisfied customers
58MVP080 model got the heat exchanger issue. I have tech
Hi Pearl,58MVP080 model got the heat exchanger issue … read more
Billy
Billy
Journeyman Service Technician
State Licensed Mechanical Contractor
9,330 satisfied customers
Need a heat exchanger for model GIN 80bu-1000 14B-3A; ser. #
need a heat exchanger for model GIN 80bu-1000 14B-3A; ser. # 1607K 03798 … read more
Airheatman
Airheatman
Heating & Air Conditioning Contractor
6 years college
1,836 satisfied customers
Have a tempstar furnace that wont close pressure switch.
Have a tempstar furnace that wont close pressure switch … read more
Phil
Phil
Mechanical Engineer
Degree, Mech Engr Technology
6,877 satisfied customers
Is it unsafe to have a cracked heat exchange on your
Is it unsafe to have a cracked heat exchange on your furnace? … read more
Rick the plumber
Rick the plumber
Owner
9,857 satisfied customers
I need a heat exchanger kit for a weil-mclain ultra 105, no
i need a heat exchanger kit for a weil-mclain ultra 105 … read more
Phil
Phil
Mechanical Engineer
Degree, Mech Engr Technology
6,877 satisfied customers
How do I check heat exchanger for blockage. Today. Sounds
how do I check heat exchanger for blockage JA: I'll do all I can to help. How long have you been dealing with this? Customer: today JA: Do you plan on doing the work yourself? Customer: yes JA: Anythi… read more
Rick the plumber
Rick the plumber
Owner
9,857 satisfied customers
When were stainless steel heat exchangers required for
When were stainless steel heat exchangers required for residential usage and/or what HVAC company was the first to provide them. And are they as effective as touted.… read more
D.E. Anderson
D.E. Anderson
Industrial Refrigeration Service Manager
200 satisfied customers
We have a tempstar furnace with a ecm motor that is hooked
we have a tempstar furnace with a ecm motor that is hooked to the air conditioner that when it starts on air the motor pulses fast then slow and then stops for a bit and restarts .Checked bearings on … read more
Charles Bodenheimer
Charles Bodenheimer
Owner
Associate Degree
78 satisfied customers
I have a tempstar furnace a few yrs old and this morning no
I have a tempstar furnace a few yrs old and this morning no heat get an error code of three the pressure switch appears to be working … read more
Rick the plumber
Rick the plumber
Owner
9,857 satisfied customers
Have a tempstar furnace two years old and the light is
Have a tempstar furnace two years old and the green light is blinking 7 times and stopping no heat in the house… read more
Rick the plumber
Rick the plumber
Owner
9,857 satisfied customers
I have a Tempstar Furnace Model number NUGK125DK08. I need
I have a Tempstar Furnace Model number NUGK125DK08. I need and schematic diagram and to know what fan control I need to buy for it.… read more
gotoman for ac
gotoman for ac
HVAC Service manager and owner
Associate Degree
4,135 satisfied customers
Funky smell coming from heat exchanger outside...... repair
funky smell coming from heat exchanger outside...... repair guy said the gas not m ixing with the air properly..true? said probably just clogged … read more
Billy
Billy
Journeyman Service Technician
State Licensed Mechanical Contractor
9,330 satisfied customers
Tempstar furnace won't come up to temperature with filter
tempstar furnace won't come up to temperature with filter in … read more
gotoman for ac
gotoman for ac
HVAC Service manager and owner
Associate Degree
4,135 satisfied customers
My tempstar furnace blows cold air periodically. I've
Yes I've already changed the hot surface igniter/flame sensor … read more
Rick the plumber
Rick the plumber
Owner
9,857 satisfied customers
I have a tempstar furnace, the blower and inducer motors
I have a tempstar furnace, the blower and inducer motors continue to run even if I take the wires off the thermostat. I have checked the low voltage fuse and it is fine. Additionally when it was calli… read more
Rick the plumber
Rick the plumber
Owner
9,857 satisfied customers
Heat exchanger is a month old and heat stopped working.
Heat exchanger is a month old and heat stopped working. Three lights are blinking saying it is a limit or rollout switch … read more
Gaztech
Gaztech
Technician
Vocational, Technical or Trade School
1,142 satisfied customers
The condensation water leaks from heat exchanger near the
The condensation water leaks from heat exchanger near the filter and comes on the ground tray. There is no blockage of any sort. What needs to be done for auxiliary condensation tray if it is cracked.… read more
Gaztech
Gaztech
Technician
Vocational, Technical or Trade School
1,142 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less

Ask Your Question

x