forced air question


  #1  
Old 10-05-04, 06:09 PM
S
Member
Thread Starter
Join Date: Oct 2004
Location: middle of nowhere
Posts: 68
Received 0 Votes on 0 Posts
forced air question

I have a electric forced air heater. It is older and has been painted over many times. therefore I do not have any model # or identification on it.
however, I do have a small problem with It. only occurs when using heater. this never happens when I am using the AC.

The heater cycles on and the fan starts and it does what it should. every now and then (random) the heating elements will turn off but the blower fan will stay on constantly after the desired temp has been reached on house. I know that there is a saftey feature that keeps the fan on for a bit to cool down the heating elements. this is not what I am referring to. the fan will stay on until the heater elements got through another cycle again. then it may or may not actually turn it off after that cycle. sometimes it works fine. other times it just stays on for a few cycles or indefintly.

could it be the heater itself or the thermostat?
any help would be appreciated.

brad
 
  #2  
Old 10-07-04, 12:29 PM
mattison's Avatar
Member
Join Date: Mar 2003
Location: Cinti, OH
Posts: 5,547
Received 0 Votes on 0 Posts
I doubt it's the stat. Probably the fan relay. Next time it does this whack the side of the furnace and see if it shuts off.
 
  #3  
Old 10-10-04, 05:39 PM
S
Member
Thread Starter
Join Date: Oct 2004
Location: middle of nowhere
Posts: 68
Received 0 Votes on 0 Posts
I waited till it did it again and I went up there and tapped (what I believe to be the fan controller) and it popped off like it should. Ill do it again a few more times and if it keeps doing this ill replace it.

thanks for your help.
brad
 
  #4  
Old 10-10-04, 06:45 PM
S
Member
Thread Starter
Join Date: Oct 2004
Location: middle of nowhere
Posts: 68
Received 0 Votes on 0 Posts
ok, I have tested it a few times and it seems to be the culprit. I have also noticed that the 60 Hz hummmm is also originating from this device.
so i think I need to replace it.
from what I gather its a SPST relay.
the part # on it is obsolete, 84-20102-101A
so how do I go about finding a suitable replacement.

other info typed on it is:
AC only 250 V
FL 8A LR 25A
coil 24 V 20-60 Hz

I gather this is a 24 V coil fed 250 V max SPST relay.
what does the FL and LR mean?
 
  #5  
Old 10-11-04, 09:26 AM
Ed Imeduc's Avatar
Member
Join Date: Aug 2002
Location: Mountain Williams Missouri
Posts: 18,386
Received 1 Vote on 1 Post
Wink

The FL is full load amps and the LR is locked rotor Amps.

With what all you have there any hvac shop or see if you can buy at Grainger or Johnstone Supply they will have a relay that will work for you.

ED
 
  #6  
Old 10-11-04, 03:31 PM
S
Member
Thread Starter
Join Date: Oct 2004
Location: middle of nowhere
Posts: 68
Received 0 Votes on 0 Posts
got a new one at grainger, cross ref. it to a white rodgers 90-290Q fan relay.
works nice.

1 more quickie.
I think my sequencer is not working rite as well, im not sure.
When I move the tstat on and off, the fan cuts out immediatly.
I always thought that the fan would run a for a min or so after the heating elements shut off in order to cool them.

am I right or wrong?
 
  #7  
Old 10-11-04, 04:55 PM
Ed Imeduc's Avatar
Member
Join Date: Aug 2002
Location: Mountain Williams Missouri
Posts: 18,386
Received 1 Vote on 1 Post
Wink

If that is what you had?????? Some do have a run time after the furnace shuts off not all of them. If so and they gave you the right relay it should work ok. You could talk to them and see if they had one with a time delay in it.

ED
 
  #8  
Old 10-11-04, 05:21 PM
S
Member
Thread Starter
Join Date: Oct 2004
Location: middle of nowhere
Posts: 68
Received 0 Votes on 0 Posts
this was before i replaced the fan relay. before I did this the fan would cut out immediatly after moving the tstat around.
the original problem, the fan would run indefinitly after heating elements turn off is fixed with the fan relay replacement.

before i replaced the fan relay and now after the new relay, the fan still operates the same apon moving the tstat, it cuts out immediatly after moving tstat.

so, i believe there is an issue with the sequencer.
is there away to test it? the sequencer looks a little rusty inside.
what can I do?
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: