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-   -   Furnace Fan (http://www.diychatroom.com/f17/furnace-fan-84576/)

elayr 10-21-2010 06:07 PM

Furnace Fan
 
elayr:
I primarily heat my bi-level home with wood, a stove downstairs and an insert upstairs. I also have an electric forced air furnace that I use when it is extremely cold to ensure the rooms farthest from the stove/insert are adequately heated. I was thinking that I probably could run just the blower (fan) on my furnace to recirculate/distribute warm air to these rooms via the ductwork/registers there in. The furnace is controlled by an Emerson thermostat, model EHO -130. Can one of you HVAC guys tell me how to do it? http://www.diychatroom.com/images/icons/icon5.gif

kenmac 10-21-2010 10:15 PM

could be easy for DIYER to do or hard DIYER to do. Depends on the heater

beenthere 10-22-2010 04:46 AM

Does your thermostat have a G terminal.
Does your electric furnace also have a G terminal. Is a wire already connected to these terminals if they have them. If not, is there a spare unused wire at the thermostat that you can use on the G terminal.

elayr 10-22-2010 10:24 AM

Furnace Fan
 
Hi Beenthere - pardon my ignorance, however, what is a "G" terminal and how do I identify it? A few years back a serviceman showed me that he could start the fan by using a pair of needlenose pliers. He simply used the pliers (kinda like a jumper cable) and touched two terminals inside the furnace near the low voltage transformer. I presume these wires went to the thermostat, however, I don't remember which ones he connected!Does this info help? v/r elayr

kenmac 10-22-2010 11:17 AM

On the t.stat you will have a terminal labeled G. also at the furnace / air handler . G is a fan relay. When you turn the t.stat to fan on . you energize the fan relay

elayr 10-22-2010 03:27 PM

Furnace Fan
 
Thanks you guys for working my problem! To answer your questions:
1. Does your thermostat have a G terminal?
Yes, the thermostat has a G terminal
2. Does your electric furnace also have a G terminal?
Yes
3. Is a wire already connected to these terminals if they have them?
Yes, there is a wire connecting these terminals.

Comment: kenmac stated: When you turn the t.stat to fan on, you energize the fan relay.
elayr comment: This cheapo thermosat is basically an on/off switch. There is a mercury switch under the cover that completes a circuit when the "spring" indicator moves. There is no "fan on" (is this a switch or switch position on more expensive models?).
Observation: The fan will only start if the circuit breakers to the heating element(s) are closed.
Your thoughts please, v/r elayr

beenthere 10-22-2010 04:00 PM

Need a newer thermostat if your doesn't have a fan on setting.

elayr 10-23-2010 12:54 PM

Hey Beenthere - I'll get a new thermostat with a "fan on" feature. My next question is: The installed thermostat I have has only two wires to it from a cable in the wall that has 4 unused wires (total 6, that sound right?). When I install the new thermostat how many more wire cinnections will I need and to what terminals. I found a schematic on the inside of furnace that shows the G terminal and others. Do you think I nees to have a "pro"
do this, or can you talk me through it? v/r elayr

kenmac 10-23-2010 02:59 PM

If all you need is for fan on. Connect green wire to G at t.stat. At the furnace connect green wire at G. Be sure to turn power off so, you don't short out & fry the transformer

elayr 10-23-2010 03:32 PM

Furnace Fan
 
Kenmac - all I want is "fan on". The intent of this project was to maximize the heat from my wood stoves by recirulating the air to those rooms farthest from the stove that need a little more heat. I'll follow your directions and ensure the the ends of the green wires are in place. Once I restore power to my "green wire" connection, what's next? Do I slide the lever on the bottom of the thermostst to close the mercury switch/green wire connection circuit and expect the fan should to come on? If not, then what do I do? rsvp v/r elayr

beenthere 10-23-2010 03:33 PM

if the new thermostat you get is battery operated.
Then you will only have to connect one of those other wires(preferably the green wire) besides the 2 already being used.

kenmac 10-23-2010 10:01 PM

Quote:

Originally Posted by elayr (Post 521890)
Kenmac - all I want is "fan on". The intent of this project was to maximize the heat from my wood stoves by recirulating the air to those rooms farthest from the stove that need a little more heat. I'll follow your directions and ensure the the ends of the green wires are in place. Once I restore power to my "green wire" connection, what's next? Do I slide the lever on the bottom of the thermostst to close the mercury switch/green wire connection circuit and expect the fan should to come on? If not, then what do I do? rsvp v/r elayr


You will just flip the switch on the t.stat. (Depending on what type t.stat you use) to FAN ON

elayr 10-24-2010 02:18 PM

Furnace Fan
 
kenmac - first - I have a green wire connection. second - This 30 year old furnace has two heating element circuits with breakers on the front of the furnace panel. I'm pretty sure one is "low heat" (5Kw) and the other is "high heat (10Kw)". The fan will run (fan on) if the "lowheat" (5Kw) heating element circuit is "on". The fan runs, however, the "low heat element" is energized as well. Does this explanation do anything for you? v/r elayr

beenthere 10-24-2010 02:23 PM

You need a different thermostat then you have.

You need one with a fan AUTO ON switch.

elayr 10-24-2010 11:38 PM

Furnace Fan
 
Beenthere - the thermostat I have now is a "two wire system", hey?
A thermostat with the Fan Auto On switch uses how many wires?
I previously mentioned that there are other colored wires bundled in the cable from the furnace to the thermostat that aren't being used on this "two wire" thermostat. I'll undoubtedly need some of them when I change to the Fan Auto On switched thermostat. I'll try to procure a Fan Auto On switched thermostat tomorrow. Stand By please. v/r elayr


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