Manual Control of Central HVAC Furnace Blower

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J

JPinnell

Member
Jan 16, 2009
12
Meramec Caverns
We have an ALL electric home. Since we're rural I wanted some backup heat option. Electric Furnace no heat pump (just strips) and the worst bill we ever had in the 5 yrs we've been here was $300 ($.07-ish/Kw) which I didn't consider to be too terrible. Since the wife is cold natured and used to radiant heat I opted to install an Englander NC13 last year. Love that little stove!! 25% off @ Lowes in Jan '09. Around $2500 total for the flue, hearth, etc but 3 yrs ROI only burning part time.

The house is a ranch and not really a very open floor plan. I thought I'd be able to move the heat around with the furnace blower since the air return is about 15 ft from the stove at ceiling level. It works somewhat. The problem is I can't switch off the blower after I've switched it on manually at the thermostat, it just continues to run. Seems that if the thermostat temp (72º) is set lower than the ambient (80º) in the house the blower continues to run until I throw the breaker to force it off.

Is this some safety circuit meant to protect the heating coils from burning out? Should I just leave the blower running all the time if I'm running the stove and forget about this? Is there a different programable thermostat I could use?

Thanks

- JP
 
The manual switch on the thermostat is a fan override switch. It turns on the fan, regardless of the temperature setting on the thermostat. To turn it off, just switch the fan back to Auto on the thermostat.
 
Sounds like a defective thermostat, sticking relay in furnace or incorrect wiring from thermostat to furnace.
 
That sounds really logical in theory, but unfortunately I already tried that. Moving back to Auto results in the furnace blower continuing to run when the stove is going. I do now that the manual override function works just fine in the non-burning season.

I have a LUX9000 programable thermostat. It's a 4 wire thermostat. I have options for Cool-Off-Heat for the system and Auto-On for the Blower. If the ambient temp in the house is 79º and the Thermostat is set for Heat and 73º the blower on "Auto" it won't autorun since it's warmer in the house than 73º. If it turn the blower to "On" it will start up and run but if I switch it back to "Auto" it doesn't turn off and continues to run (hours) until I throw the breaker to reset it. Even if I disconnect the thermo after initiating a manual start on the blower it will continue to run. That's what makes me think it's something in the furnace control making it continue to run?

Ideally I'd like to have the Furnace set to "Heat" to 70º or so and the blower on "Auto" so if the stove dies down the furnace kicks in as backup. When I'm around the house I'd like to kick on the blower to attempt to even out the temp throughout the house, but I don't want the blower running 24/7.

- JP
 
find your lux paperwork and call their tech line. they should be able to walk you thru it. if you don't have the paperwork call where you bought it for number. i have to call tech lines for problems on thermostats and boilers every now and then and they are pretty good. not like the phone company or computer tech lines.
 
I think you are on the right path looking at the furnace controls. If you turn the tstat back to auto the fan should kick out. Sounds like the control circuit that tells the relay to drop out is not working correctly in the furnace. Once you turn the breaker off to the furnace, the relay drops out. If you just replace the furnace, tstat, & wiring that should get it going. :)

Sometimes they send a little book type thing with these devices, from what my wife tells me, they contain information about the unit. I choose not believe it and proceed with the above replacement regime. Sure it costs a little (lot) more, but I can say that I fixed it. Don't need no stink'en manual! :coolgrin:
 
Possibly just the setting/jumper configuration on that thermostat. Give the tech line a jingle. could also be the blower relay sticking.
 
Cross the "R" terminal to the "G" terminal on the T-stat. That should start the blower in the furnace, and the blower should run only as long as those two terminals are jumped out. If the blower stops running when you remove the jumper, your problem is with the T-stat. If the blower keeps running after you remove the jumper, it's something in the furnace.

Some units have a temp sensor in them that will make the blower run, it's like a built-in over ride, to move the air if the temps inside get too high. Could be that, but I would be suprised if it was.

Maybe a sticking blower relay in the furnace.
 
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