funace fan keeps running but only sometimes

Reply

  #1  
Old 11-24-11, 07:35 PM
Member
Thread Starter
Join Date: Sep 2004
Location: usa
Posts: 221
Received 0 Votes on 0 Posts
funace fan keeps running but only sometimes

forced air gas furnace
Fan will keep running after burners shut off. It dont do it all the time. It will keep running until I either shut the furnace off or it I lower temp it will also shut fan off.
ANY ideas what I should look for or check. I have put a new fan switch on it already.
 
Sponsored Links
  #2  
Old 11-24-11, 11:54 PM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 5,503
Received 0 Votes on 0 Posts
Please post the model and make of the furnace which can be obtained from the rating plate in the burner compartment of the furnace.
 
  #3  
Old 11-28-11, 09:15 AM
Member
Join Date: Dec 2007
Location: USA
Posts: 227
Received 0 Votes on 0 Posts
I am not a pro. My furnace typically runs for a few minutes after the flame cuts off. I think it runs until the temp drops to a certain point, but it could be a timer or something I am not aware of. It may be that your furnace is not cooling off fast enough.

It may also be that your thermostat is telling the furnace to run fan only for some reason or malfunctioning. It might be worth while buying one of those cheap round honeywell thermostats that only work off temperature and have no other functions and see if it works with that.

If your furnace is very old take this opportunity to replace it with something that runs cheaper and with no troubles.
 
  #4  
Old 11-30-11, 04:05 PM
Member
Thread Starter
Join Date: Sep 2004
Location: usa
Posts: 221
Received 0 Votes on 0 Posts
model number

furnace is a Duomatic Olsen
Model number is HCA100ND4R
serial number 890518222

Have programmable thermostat, for the most part, frunace runs good when program is running. But if I change heat temp to override the program is when it seems to act up but not always. It has also done it when running program but less times this way
I know its suppose to run to cool down to certain point, but it never stops running until its shut off.
 

Last edited by tecate87; 11-30-11 at 04:21 PM.
  #5  
Old 11-30-11, 05:51 PM
airman.1994's Avatar
Member
Join Date: Dec 2005
Location: VA
Posts: 5,781
Received 5 Votes on 5 Posts
Let me add that you should run your fan 24/7 in heating mode for good IAQ and to help with cold spots
 
  #6  
Old 11-30-11, 06:41 PM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 5,503
Received 0 Votes on 0 Posts
Heh, heh! I guess we know how you came by your nome de plume "Airman"!


If someone wants to run their fan all the times they are free to do so of course. Most people find circulating air that hasn't been heated by the furnace to be drafty and unpleasant. Also the cost of running the fan 24/7 is significant and those who do so are often required by manufacturers to lubricate the fan motor more often --- annually rather than each five years might be common.

In short, there are very good reasons why most people choose not to run a fan 24/7.
 
  #7  
Old 11-30-11, 07:56 PM
airman.1994's Avatar
Member
Join Date: Dec 2005
Location: VA
Posts: 5,781
Received 5 Votes on 5 Posts
First the motor is designed to run so running it will put no more wear on it than starting 30 times a day. Yes older AC motors will cost to run them. But there should be less of a call for heat because the air is always mixed. A major benefit is you will always have filtered air which is good because the air is dryer in the winter which will leed to more dust. If the air fills drafty you have either a bad duct design or poor registers or both. Motors that need oiling are a thing of the past. I will also add that the DC motor use a lot less electricity.
 
  #8  
Old 01-08-13, 11:03 AM
Member
Thread Starter
Join Date: Sep 2004
Location: usa
Posts: 221
Received 0 Votes on 0 Posts
old post of mine but back to having issue again.

furnace will seem to runs fine for days. Then some evening, morning or afternoon the the house will start to get cold, we look at the thermosat setting. It may be set at 68, fan running but actual temp will be 66 and blowing cold air. If we leave it go it never heats up. fan will continue to run and be cold. Only thing that seems to be somewhat consistant is mabe it happens when its colder outside which I dont know wha that would have to do with it.

the other day I was turning off furnace and watching it cycle, when I turned it back on, the furnace tried to light but didnt, then fan came on instantly and continued to run with no heat.
after watching this I dont know now if this is whats happening all the time or now.
any help would be great.
I can use a multi meter with telling me what to test.
 
  #9  
Old 01-08-13, 05:09 PM
hvactechfw's Avatar
Member
Join Date: Jan 2011
Posts: 6,245
Received 0 Votes on 0 Posts
Is there a control board with flashing diagnostic LED in your furnace? What code does it flash when the furnace does not operate properly. Describe in detail the sequence of events that happens with a call for heat.
 
  #10  
Old 01-08-13, 06:16 PM
Member
Thread Starter
Join Date: Sep 2004
Location: usa
Posts: 221
Received 0 Votes on 0 Posts
its an older furnace and I dont think there is a led light for codes.


not positive of exact sequence.
We notice it when the fan constantly runs and gets cold.
but,
thermostat calls for heat, light on thermostat comes on, what I think possibly happens is the furnace never lights but the fan comes on and never shuts off.
if this is not the case. it would cycle thru normal steps, thermostat reaches temp but fan keeps running until we notice the cold. I know it is suppose to run some after heat goes off but it just keeps going and starts to cool down the house. thermostat will be set like 70 and will read 68 with cold air blowing.
 
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
Display Modes
 
Ask a Question
Question Title:
Description:
Your question will be posted in: