Go Back  DoItYourself.com Community Forums > Heating, Cooling, Air Conditioning, Ventilation and T-Stat Controls > Air Conditioning and Cooling Systems
Reload this Page >

heil unit system fan ( Inside blower ) and heater exhaust fan runs continuously

heil unit system fan ( Inside blower ) and heater exhaust fan runs continuously

Reply

  #1  
Old 10-31-17, 07:17 AM
A
Member
Thread Starter
Join Date: Oct 2017
Location: United States
Posts: 9
Received 0 Votes on 0 Posts
heil unit system fan ( Inside blower ) and heater exhaust fan runs continuously

2000 Heil unit 2.5 ton gas heat . noticed the other day the house fan on and exhaust fan on gas pac , tried to turn off by t.stat no go.
only way to stop it was to use master disconnect
ac and heat INOP. nothing changes just fans run
removed the stat still running.
went into unit disconnected all the tstat wires .still running.
removed red wire from 24v trans , all stopped
assumed a bad board , replaced with known good one , still same !
checked transformer output 26v O.K. is this a default if failed ?
there is no LED fault light .
I can do detailed electrical check throw it at me !!
winter is just around the corner and i need the heat, please help !!
thanks
 
Sponsored Links
  #2  
Old 10-31-17, 07:27 AM
R
Member
Join Date: Oct 2016
Posts: 1,722
Received 92 Votes on 86 Posts
Remove the thermostat wires from the terminal block in the furnace. If that fixes the issue, ring out the thermostat wire between the furnace and thermostat to check for shorts.
 
  #3  
Old 10-31-17, 09:10 AM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,423
Received 17 Votes on 14 Posts
It sounds like you have a tripped limit.
Are you saying that this board is not equipped with a diagnostic light or that it has one but isn't giving a code?

What is the model number of this furnace?
If it has a Honeywell "smart" valve I would also check this for an LED light or loose harness connection.
 
  #4  
Old 10-31-17, 11:29 AM
A
Member
Thread Starter
Join Date: Oct 2017
Location: United States
Posts: 9
Received 0 Votes on 0 Posts
I isolated the wires at the term. block first thing to eliminate shorted wireing , as stated in complaint
its not in the wiring to the stat.
thanks arnie
 
  #5  
Old 10-31-17, 11:40 AM
A
Member
Thread Starter
Join Date: Oct 2017
Location: United States
Posts: 9
Received 0 Votes on 0 Posts
thanks houston204
do not know model number but board has NO lights Part# HQ1084197HW ST9120C 5005 Honeywell
Please elaborate on the tripped limit ?
thanks Alpine
 
  #6  
Old 10-31-17, 12:11 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,423
Received 17 Votes on 14 Posts
https://customer.honeywell.com/resou...0s/69-0781.pdf

I would measure for an open circuit to the limit control and rollout switch.

It looks like they land on the 1st and 6th terminals in this manual...
 
  #7  
Old 10-31-17, 12:53 PM
A
Member
Thread Starter
Join Date: Oct 2017
Location: United States
Posts: 9
Received 0 Votes on 0 Posts
I guess if the limit switch stayed open ,the unit thinks over heat ! . thus leaves the fan on to cool down system ?
some sort of default . i will check the chamber limit switch diaphragm , and rollout see if tripped tonight.
this unit was supposed to be converted to propane , do you know the orifice size of natural gas and propane ?
may be it is really overheating ? it has NOT been used in 4 years, bought used ,my old one compressor went .
so i have extra parts to work with. Hopefully between to 2 should be up and running soon .
thanks Alpine
 
  #8  
Old 10-31-17, 01:07 PM
A
Member
Thread Starter
Join Date: Oct 2017
Location: United States
Posts: 9
Received 0 Votes on 0 Posts
ran a copy of the manual you sent on my way home with meter to check
thanks
 
  #9  
Old 10-31-17, 01:21 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,423
Received 17 Votes on 14 Posts
A roll out switch with usually have a reset button.

 
  #10  
Old 11-01-17, 06:58 AM
A
Member
Thread Starter
Join Date: Oct 2017
Location: United States
Posts: 9
Received 0 Votes on 0 Posts
roll out switch was the problem ! Thanks for all the help !!
reset it Understand its from a roll out flame .
but what are some of the problems that can cause it to trip ?
what to look for , to solve the problem.
thanks alpine
 
  #11  
Old 11-01-17, 07:18 AM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,423
Received 17 Votes on 14 Posts
I would watch it burn until after the blower starts. A hole in the heat exchanger could cause flame roll out when the blower starts.

I would also make sure that a carbon monoxide detector is in the house.
 
  #12  
Old 11-01-17, 07:32 AM
A
Member
Thread Starter
Join Date: Oct 2017
Location: United States
Posts: 9
Received 0 Votes on 0 Posts
I guess the only way to know is to pull the exchanger check for holes ?
I watched the flame on start ,anticipating a possible rollout seemed fine .
would it be possible to smell propane in the home ?
is the exchanger easy to remove ?
thanks Alpine
 
  #13  
Old 11-01-17, 09:21 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 56,451
Received 761 Votes on 715 Posts
If the heat exchanger had a hole in it..... it would be very possibly to smell propane in the house. It all depends on how well the burner is burning the fuel. What you will get is CO which has no smell. Some heat exchangers are easy to remove but most are not. Many times they are inspected in place with a camera and probe.
 
  #14  
Old 11-01-17, 11:29 AM
A
Member
Thread Starter
Join Date: Oct 2017
Location: United States
Posts: 9
Received 0 Votes on 0 Posts
well the wife just called , No heat and fan stays on,
she did say she smelled propane last night . ( that was said in AM before I left for work )
leaving early today to possibly swap out the blower case.
hope it slide out from front .
thanks Alpine
 
  #15  
Old 11-02-17, 06:28 AM
A
Member
Thread Starter
Join Date: Oct 2017
Location: United States
Posts: 9
Received 0 Votes on 0 Posts
heat exchanger had rust holes, did the fan on gas off pressure test with paper flame prior to removal, sure enough lots of flame flicker ,
had the old one out new in 2 hours not bad , Do IT yourself !!!

Thanks so much for the expert help I received on this sight Houston204 and pgmax
Alpine
 
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
 
Ask a Question
Question Title:
Description:
Your question will be posted in: