Running my Evcon furnace fan in the summer?


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Old 05-14-22, 02:51 PM
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Question Running my Evcon furnace fan in the summer?

Hello I have an Evcon furnace, model number RGF1L080BP12MP11A. I'd like to run the fan on this in the summer, as I've read that doing this to circulate the air in your house can help keep the temperature down. We live in a pretty old house without central air, and anything we can do would be a big help.

I have an Emerson thermostat, model 1F78-144 a cheapo thing our electric company gave us when a power surge killed our old one. I can set the fan to "auto" or "on," and the system to "heat," "off," or "cool." From what I've read, I need to set the fan to on and the system to cool, then set the temperature below whatever it's currently reading as. Unfortunately, this isn't turning the fan on.

I've removed the panels from the furnace and don't see any kind of switch I could hit to turn on the fan. I've seen that sometimes you need to install a "summer switch" to accomplish this. Is that what I need to do? Or do I have what I need already and just not know what I'm doing? Probably incidental, but I read that you should shut off your gas at the valve, and have done so.

Thanks in advance for any advice you can give. If it's helpful, I can get shots of the furnace with the panels off, or anything else that might be of use.
 
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Old 05-14-22, 03:12 PM
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Follow-up: We also have — pretty unusually, I think — a second furnace in the attic that services our second floor. My understanding of this air circulation idea is that, if I had that furnace's fan going, I'd just be pushing all that hot attic air down into the house, which would be extremely counterproductive. Is that about right? Or would it be helpful to run that one as well?
 
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Old 05-14-22, 04:08 PM
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Welcome to the forums.

In most hot, humid areas.... air circulation is of little use. If using A/C..... keeping the blower on after the compressor shuts off will evaporate the moisture off the coil and back into the air. You could experimentally try it but most people haven't found an advantage.

There shouldn't be hot attic air getting into the air flow. If there is.... the ducts are not insulated properly. There should be enough attic insulation to keep the heat from getting into the second floor.

Please pull the thermostat off the wall and take a picture of the wiring.
Remove the blower service door and post a picture of the control board thermostat wiring.
How to insert pictures.
 
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Old 05-14-22, 05:08 PM
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Smile

Thank you, for the welcome and for the help! I can tell you for certain that a) the ducts in the attic are indeed not insulated properly and b) there is not enough attic insulation to keep the heat from getting into the second floor. This is a very old house, not particularly well-maintained throughout its life, and we bought it from a house flipper who turned out to have absolutely no idea what he was doing. We're working on things as time and money allow, and at least 80% of it so far has been fixing the stupid, cheap, and/or downright dangerous stuff he and his contractors did.







 

Last edited by PJmax; 05-14-22 at 05:47 PM. Reason: resized/labeled pics - added 4th pic
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Old 05-14-22, 06:00 PM
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a house flipper who turned out to have absolutely no idea what he was doing.
He knew exactly what he was doing.... cutting corners to make a profit. I see it every day.

Ok... I misunderstood you. You have only a furnace there....no A/C in that furnace.
You'll see I modified your pictures. You're lucky..... you need three wires and you have them.

At the furnace end.... turn power off and put the three wires where shown on the board.
Red on R, Green on G, and White on W.

At the thermostat.... same thing...... make sure there is a jumper from Rh to Rc.
When done changing wiring... turn furnace back on.


Emerson 1F78 thermostat manual - pdf
 
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Old 05-14-22, 07:08 PM
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Talking

This is exactly what I needed; thank you so much!
 
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Old 05-15-22, 03:14 AM
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Originally Posted by Detroiter
I'd like to run the fan on this in the summer, as I've read that doing this to circulate the air in your house can help keep the temperature down. We live in a pretty old house without central air, and anything we can do would be a big help.
I'm in similar situation- 1700s 2.5-story stone farmhouse, 1800s 3-story addition, 1990s 1-story addition:

Oil furnace, forced air circulation- no central A/C. In spring and fall, I set the thermostat to 'cool' so it kicks the fan on at around 75 degrees. That really helps even out the temperatures, and having some airflow helps keep it comfortable.

In summer, since I've got an old, unfinished masonry basement; I pull the access panel off the furnace in the basement, slide an air-filter into the opening, and then when my thermostat calls for A/C, it pulls the cool air from the basement and circulates it through the house. Last few years, simply running that fan has worked as A/C until around July-August. Once the house heats up, then and only then do I have to switch to window A/C units.

Should ALSO mention that older homes with high ceilings and central staircases were generally designed to make use of passive air-conditioning: by letting the hot air rise to the ceiling, flow up the stairs, and then up to the attic and out a vent. Since I've got 2 staircases from main-house + addition, I take full advantage of that, and it does make a difference when you vent the house hot air up to the attic. Also helps to leave a ground level shaded window facing North-East open to let in relatively cool air to assist the passive cooling from the "chimney effect"...
 
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Old 05-15-22, 09:35 AM
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Now you can set the unit to cool.
When the temperature rises over the set point the blower will come on.
 
 

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