Furnance overshooting set temperature

[Swimmer22]

I have a question related to a manufactured home (16x80) I purcased this spring. It is a new 2005 unit with a Miller (Nordine) hot air oil gun furnace with A/C. The problem is when the unit kicks on to heat the home, it runs too long and overshoots the desired temperature significantly. If set at 72 degrees, the furnace runs and the blower doesn't stop until the inside temperatue is around 79 degrees.
Also, once the unit stops, approximately 4 miuntes or so later, the blower kicks on again and runs for a short time (probably a minute) then shuts off. When it does this, the oil furnace is not running, just the blower.

Can anyone tell me what may be wrong with this unit. Is there some place to set or adjust the furnace so it is not overshooting the set temperature so significantly? Also, should the blower be kicking in and running a second time like it does? I hope something can be done as it goes from chilly to sauna everytime the furnace runs....... Thanks.

[Eugene]

Ok, I know what the problem is.
Under the therostat cover, there is a sliding pointer that is called the "accuator " (I probably spelled it wrong.
This setting adjusts the blower timing, exactly what you are talking about.
Check in the installation instructions for the furnace to find the right setting.
If I remember correctly, it should be set at .3, however, make sure you check in the furnace instructions.
That should take care of your problems.

[Roger]

I had a problem like this. The wiring to the back of the thermostat was incorrect. If you are not sure of how it should be wired, contact a HVAC guy.

[jgn]

The problem depends on your thermastat. If it an older one it uses a mercury switch that causes contact. If the thermastat is not level it will not work properly. You can install an electronic one and that should solve the problem (they are $30-50 and not difficuly to install. The unit kicking on normally means the heat exchanger has not cooled down and needs to vent so the fan comes on without the burner.

[peter]

for a Miller hot air furnance(?15/20old) or web so i do a print out. the family had no knowledge when it was put in. I'm electrcian by trade, i was ask a ? can i fix the problem. I had no answer for family. If you can help me,
thank you.
peter

[rmurray]

You will need a little more info..such as..fuel type......model number...

Looks like lots of info and parts here if oil furnace.....

http://beckwithheating.beckwith.net/millerparts1.html

This place is a distreibutor....

http://www.millerac.com/

Miller equipemnt is made by Nordyne.....

They are here with specs and info on many models...Including the "Classic CMF series" gas and oil furnace....

http://www.millerac.com/

This should get you started...Good Luck..

[Jim Johnson]

I have a nordine furnace model#g6rc-100r-16b and it will not ignote. The gas is on and the pre-ignition blower comes on but it fails to ignite. The red light on the circuit board will come on aand then flash steadily but the yellow light does not come on. This furnace is one tear old and worked fine last winter and nothing was done to it.









1 Jim