It needs to be ON, Auto will not let the fan only run, the way it is wired.Quote:
Originally Posted by PistolPete76
If you want the T-Stat to control the blower only when calling for cooling then it will need to be rewired, from the norm.
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It needs to be ON, Auto will not let the fan only run, the way it is wired.Quote:
Originally Posted by PistolPete76
If you want the T-Stat to control the blower only when calling for cooling then it will need to be rewired, from the norm.
What would have to be changed for that to work?
Do you have the jumpers between the RC and RH as shown in the 3-wire heating diagram?
When the fan switch is in auto, the furnace or a/c generally control the fan, an only indirectly from the thermostat. On heating, it turns on when the air by the heat exchanger gets warm (on many, but not all). On a/c, it often turns the fan on immediately when it calls for cooling. So, if you tried to fool the furnace into thinking it has an a/c unit attached, and you wanted the thermostat to control the fan being on/off, instead of the G terminal, move it to the Y terminal on both ends, and make sure that the thermostat is in the cooling mode. But, if it is wired per the 3-wire heating diagram (with the jumper), putting the fan switch to ON should turn the fan on ANY time the furnace is powered up. The G wire is an override from the furnace's normal control of the blower. When in AUTO mode, the lead is not used, the blower control is all within the furnace based on the thermostat calling for heat/cold, and other internal conditions.
Just tried to run the fan only on heat but no go. The fan will not turn. So far only way i got it to work is on auto with heat (like it's always been, but that's only good for winter) I'll try to move the wire to y terminal later on when i have a minute and see what happens.
BTW yes i do have the jumper
Thanks a bunch for all your help. will let you know how the Y terminal made out
After switching the wire to Y terminal..... i got nothing :-( hmmmmm
Your furnace may not support a manual fan on function...not all do. What does the manual say about it? Most modern one do, though.
don't have a manual. it's a 10 year old furnace. It was at my place when i bought it 4 years agon.hmmmm.
Thanks for all your help.
Remember, if it is in cool mode, the house has to be hotter than the setting to turn on. It is the opposite for heat.
It looks to me that it is going to require the 4 wire hookup.Quote:
Originally Posted by PistolPete76
It will not know that the air is not installed and will run the fan trying to coll, then shut off after it reaches the therm cool setting.
Do you have 4 wires available from the Thermostat to the furnace ? What is red doing ?
You will need 4 wires if you want it to work the way I understand that you want it.
I do believe that unit is able.
Did you switch to the Y terminal on both ends and put it on cool as Jim recommended ?
I only have 3 wires right now. if i manually switch the gass off, the fan will turn on when thermostat is adjusted to heat higher than rm temp. Once on though fan will continue to work even after the temp is adjusted manually to lower heat than rm temp. (strange) Have to shut the breaker off to stop it) This work for aout option. If i set it to "on" possition to run constantly the fan will not turn on when the heat is set to lesser temp thatn air temp in the house.Quote:
Originally Posted by DonL
There is no red wire. black is hooked up to RH white to W and green to G
I'm gonna see if i can add another wire to trick it into ac mode without ac. thanks for all your help. Might take me a while to run that wire. It's been busy summer.
Running the fan will somewhat equalize the temps if the basement is fully conditioned with ducts, but it's a pretty inefficient way to achieve any cooling, and in the end could prove counterproductive:Quote:
Originally Posted by PistolPete76
A 600-1000W air handler is adding 2000-3400BTU/hr to the sensible cooling load- think of it as running a 600-1000W space heater in the house. It's unlikely that even through an uninsulated basement slab that the heat transfer through the slab would keep up with even the air-handler portion of the cooling load. A cheap 500W window-shaker air conditioner would be able to move ~2x that amount of heat OUT of the house rather than injecting heat into the house, and it would use less power.
If you're looking for the cooling wind chill of breeze on sweaty skin, use a 100W portable fan/ceiling fan, and turn it off when unoccupied. You'll be adding a lot less heat to the house that way.
If it is a squirrel cage blower then how would it be adding 600-1000W to the cooling load ?
A 1 horse motor in the air flow may.
Seems like the most you would have to loose is the Electrical power used by the blower.
The duct work may add more heat than the gain of moving the cooler air tho.
I didn't look up the power rating of the air handler on the furnace in question, but typical old school single-speed furnace blowers are in the 600-1000W range. If it's ECM drive it might only be 350W, but the principle is the same:
All power going into the blower motor eventually shows up as heat inside the building, if the air handler and ducts are all inside of conditioned space. Only a small fraction of that is the direct heating of the motor windings- the bulk of it is in the air resistance at the impellers and ducts, register etc. It's a widely disbursed space heater, but a space heater nonetheless. Energy is neither created or destroyed- 100% of the energy going into the motor ends up somewhere eventually as heat, and all of those "somewheres" are inside the thermal boundary of the house.
Quote:
Originally Posted by PistolPete76
I thought you said you had a red wire that you found behind the thermostat in your earlier post.
If you only have 3 wires , and it is working the way you say now, Then you should be able to move 1 wire at the thermostat.
The wire now connected to "W" should be moved to "Y" on the thermostat, and then it should work to cut the fan on and off in cool mode. (Need to leave the gas turned off).
Then when it gets cold and you need heat you can move the wire back, and turn the gas back on.
The long way around but should work. Running 4 wires may cure the swapping of wires, and the need to turn off the Gas.
Dana is correct that it will add some heat also, But you have to decide if it is worth it. If you have better comfort level, It must be doing some good.
Yes i have a red wire behind, but it was not used. I had to extend too for it to reach the furnace. Now it's (green) just to make it more color complicated lol.
I will try the wire switch. It's not that much work.
with the heat i see what you guys are saying. When I had it running the other day it actually got warmer than cooler. So at the end i may not even use it, but it was cool to learn something new.
Once again thanks a bunch for all your help
I know here where I live it will heat the house because all of our venting is in the attic.Quote:
Originally Posted by PistolPete76
I will use it to heat in the winter and when the sun has the attic temp cooking.
Not much use for cooling tho, if the sun is getting the attic hot.
If you swap the wires, then when it starts running all the time, that means you are starting to heat instead of cool, and you should turn it off.
The wire swap should help some.
Let us know if you have any luck.