propane furnace fan

[RTP82]

My propane furnace runs of a programmable thermostat. I have the FAN on the thermostat set to Auto. I thought this means the fan only runs when the stat calls for heat and is off other times. In my case the fan runs when heat is called for but it also runs at other times when no heat is needed or called for. Is this normal? Is there something other than the call for heat that triggers the fan?

 

[skeetska]

some programmable thermostats have a programmable fan function you can set to circulate air, say run the fan only every 20 minutes.yours may have that, check your menus to see if its setup.

 

[Redox]

I think Honeywell calls it the "Smartfan" option. It basically operates during the occupied periods. I think it might be a DIP switch on the back of older stats. It won't work at all if you don't have A/C...

Chris

 

[RTP82]

I was out of town so just getting back. Thanks for the replies. I have a new thermstat and A/C. I will check out the settings on the thermostat.

 

[blaze]

Check this first.When your thermostat shuts propane valve off the fan will keep going to cool of plenum,it could come back on if heat builds back up in plenum.This is normal even with thermostat satisfied.

 

[RTP82]

Right now my propane has not run for a least 24 hours as it was 75 here yesterday and warm again today, and my fan is running as I send this. The only way I can shut it off is the switch at the furnace

 

[blaze]

The fan control on your furnace has a switch or push in button so the fan will run continual for summer cooling sounds like it got turned on accidentally.If it is push button pull it out.

 

[RTP82]

The switch I mentioned to turn it off is like a light switch. It is on the outside of the furnace> Are you talking about another switch that is on the inside?

 

[blaze]

Yes on the inside.Did this problem start since you installed thermostat.Try turning auto back to manual something is telling the fan relay to turn on.If you have never been inside were controls are the switch would be in the automatic position.

 

[RTP82]

The t-stat has been installed for about 1 year now. I recently switched the T-stat to Auto thinking this would keep the fan from running all the time. I have a pellet furnace now and want the propane furnace to kick and the fan running only when heat is called for as secondary heat. I found the manual for the furnace and I do not see a switch for Auto, on, off for the fan. I see switches for continuous fan air flow. The book stats the Continuous fan setup switches are used to select the desired airflow when the t-stat is in continuous fan mode. I found the T-stat manual and there is a setting for fan control. 0 for equipment control (it says for gas and oil furnaces) and 1 for T-stat control (for Electric furnaces) It is set to 0 since I have a gas furnace. Can I safely set this to 1.

I hope this is not to confusing.

Thanks for the help

 

[blaze]

Leave thermostat at 0.Has the fan been running continuous since the new thermostat has been installed and before that did it turn on and off properly.Be patient because i think the thermostat is wired wrong.It is telling fan relay to turn on but you have no control of it.YOU said you see switch for continues fan in manual the switch can not be on continues or the fan will keep running the thermostat will take care of switching from manual or automatic.

 

[RTP82]

When I got my pellet furnace I noticed the t-stat had the fan set to on. I changed it to auto and at that point I thought it was working. I noticed a few days later that it was running continuously. The switches for continuous fan are set to the default which means CFM is set to low-heat mode. I still cannot find an auto or on switch on the furnace. I appreciate the help thanks

 

[Redox]

How old is the gas furnace? It is possible that you have a bad high limit switch. Many of the later models are programmed to run the fan if the high limit trips possibly caused by the pellet furnace. Does the gas burner work normally?

Chris

 

[blaze]

Start back to when you set the thermostat to auto did the fan run normal before you touched it.I am assuming the pellet stove is a separate unit not attached to propane furnace and the propane furnace is just for back up.When you take thermostat off auto what happens.

 

[RTP82]

The gas furnace is 10 years old and works well. I have had no heat running all week gas or pellet and the fan still runs.


The fan had always been set to ON and has always seemed to run normally. The pellet furnace is separate with its own t-stat. however, It is attached to the same duct work as the gas furnace. There are 3 options on the T-stat for the fan AUTO ON CIRCL I have switched between all of them and the fan continues to run on any of the 3 settings

 

[blaze]

If this fan switch you are talking about is not the main disconnect switch shut it off because you are over ridding the limit control.Run the propane furnace and let plenum get hot.The fan will run of limit control.When fan starts shut off thermostat and when plenum cools down fan will stop.If it comes back on a second time this is normal because the heat chamber could still be giving off heat.Before you try this look for the fan control on your pellet furnace .There is a fan control that turns the fan on to the propane furnace when plenum gets up to temperature.Most controls have a push button to let fan run continuous if the button is pushed in pull it out to let fan control work automatically.