Furnace problem

[heyttown]

Its a Goodman GMH950904cx purchased new in fall of 07.its either a 90 or 95% efficient furnace. Just recently it will heat up normally and I want to say it has a 2 stage blower, and you can here after the room gets up to temp, you can hear the blower step down in speed, but usually would shut off after 5 or 10 seconds of blowing..Well it will go that 5 or 10 seconds then the furnace will reignite and run for another full heating cycle. then you will hear the blower step down again..This time it will shut off until the next time the tstat calls for heat.

What would make the furnace essentially run 2 cycles before it shuts down.?


Not sure if this is allowed as I am in no way trying to sell anything,i did a google search and found my furnace.... but here is a link to my furnace which gives a complete rundown of what the furnace has...Again this is just to help inform, and not trying to sell anything.
http://www.alpinehomeair.com/viewproduct.cfm?productID=453057485

 

[marlboro180]

Re: Furnace problem

Not trying to be a wise-guy, but did you check the on-board diagnostics? The link you posted states it will store the last 5 faults....

 

[heyttown]

Re: Furnace problem

I have yet to open the panels up, but a quick look thru the site glass and I see no lights at all.

 

[marlboro180]

Re: Furnace problem

Pop the front panel off and have a look for a control board. Site glass is for visually verifying flame in the firebox.

 

[heyttown]

Re: Furnace problem

Both my upper and lower panels have site glass...I opened it up and found the circuit board with led light...

Its constant on, no blinking which in the manual reads normal operation.

I changed the filter while I was tooling around with this thing, so maybe that helps..We will see, T stat hasnt called for heat yet since I replaced filter. I will keep this thread updated.

 

[Jeep Man]

Re: Furnace problem

First rule with nearly everything electronic. Remove all power-wait 30 seconds-reapply power-restart and recheck.

 

[Tim Frank]

Re: Furnace problem

Check the anticipator setting on your thermostat. Might need to be be tweaked.
My guess is that you need to set the anticipator for a "longer" run. Check your t/stat manual.

Are you sure that the furnace is ignited right to the end of cycle 1? It should be flame-off in "anticipation" of reaching the t/stat set point and the fan should run until the residual heat is dissipated down to a lower limit switch setting when it will drop out as well. 10-15 seconds after flame-off is way too short.

We usually use the manual override and run our fan 24/7 during heat season. The motors are built to take it, you get a more uniform temperature throughout your house, and the extra energy cost is minimal, but may be offset by the furnace not running as much.

And when was it last cleaned/serviced?