Furnace and Fan

[padave65]

Driveway camped this weekend just to make sure everything works and is ready to go for the 15th. Noticed something different from my Roo. When I ran my furnace, the overhead fan of the AC unit ran. I guess that is to help with condensation/moisture. It was quite noisy. Had to crank up the TV to hear it. Is there any way to slow down the fan speed to decrease the noise? It sounds like the fan is on high.

[cfsoistman]

What t-stat do you have? Does it control both Furnace & AC? If you set the switch to Furnace that's all that should run. The blower on the furnace runs off the controls within the furnace. If you have the Fan Switch set to On at the t-stat that's why the AC Unit fan is running. Unless you want that fan to run the switch should be set to Auto. I've never heard of the two units being wired together. You may have a crossed or shorted wire at the t-Stat.

[padave65]

It has a digital display to set the temp. You can select ac, fan, furnace or off. A light eluminates by the selection. I had furnace selected. The furnace ran but so did the fan.

[cfsoistman]

Is this the T-Stat you have? If so check page 3 "D" about Furnace operations. Hope this helps.

http://www.dometic.com/FileOrganizer...eration_EN.pdf

Is this the original t-stat or has it been switched out to upgrade to Digital? If so there are a few posts showing the correct wiring diagram but you need to provide the Manufacturer and Model # for the correct diagram. Do a search in FR for T-stat Digital Upgrade.

[grhodes50]

Do you have the same one I have, Dometic?
When you select fan use the +/- to select AUTO - HI - LOW. Make sure it's set to AUTO. If you have it set on HI or LOW the fan will run while the furnance is on.

Hope this helps.

[grhodes50]

Just found a pic of my thermostat.

Dometic
Single Zone LCD Thermostat
Model #3313192.XXX Cool/Furnance


Instructions for the fan speed settings are on page 7 of the instruction manual. It does state the fan will operate continuously while set on HIGH or LOW and the fan will be off when set on AUTO.
On page 11 there is a section on Special Features. It states that when the fan is set on AUTO and the difference between the tempature set point and actual room tempature is >5° the fan will run on HIGH and when <4° the fan will run on LOW.

[M109Rrider]

Yep, same one I have......and I did the same thing until I figured out how to put it in Auto......

[padave65]

This is mine....selected fan then set it to auto and then moved to furnace...no fan. Thanks for the info. Did the trick. Can't find my manual. I do not remember getting one. thanks for your help!

[grhodes50]

No problem. Glad I coud help.

[Theburgerman1]

What about the opposite issue. I run the ac but the furnace also comes on?

[Theburgerman1]

What about the opposite issue. I run the ac but the furnace also comes on?