Original message
| psay51
 |  "Bryant blower speed reduction"
, posted Thu 10 Jan 16:28  
Bryant 383KAV042091 AGJA, series G 88BTU/HR
The blower speed is WAY too much for my ducting, and I have been told I can lower the RPMs by switching some wires on the circuit board. Could anyone tell me which wires to switch to which terminals?
As before, thanks a lot!
peace
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Replies:
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| static
| "Re(1):Bryant blower speed reduction" , posted Thu 10 Jan 21:36
You might be about to create problemos. So watch out.
Shut the power off to your furnace before you do this, of course.
Your control board will look a lot like one of these. In fact, it might be one of these. Especially if you're one of my customers :p
Note that on each one there are four terminals: 1 "Heat", 1 "Cool" and 2 "Park". Heat is the heat speed, Cool is the cooling speed and Park is where you park the unused speed wires. It's important to park them because they will also be hot when the motor is running due to back EMF.
On your furnace, Red wire = Low, Blue = Med. Low, Yellow = Med. High and Black = High. To set the speed you just plug the appropriate speed wire on to the terminal "Heat". BUT... if your blower is cranked up so high it may very well be for good reason, to keep your furnace from overheating! If you slow it down you may be endangering your heat exchanger. After you change speeds the least you NEED to do is to take a "temperature rise" (air temp. coming OUT of the furnace, about 3' away MINUS air temp going IN to the furnace) and make sure it is within the specs listed on the rating plate inside the furnace, otheriwse you are asking for trouble!
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| | psay51
| "Re(2):Bryant blower speed reduction" , posted Fri 11 Jan 08:40
Thank you, Static!
This furnace is rated at 88K BTU/HR and so a lot more than my house - 1100sq.ft - needs. But I got it used/cheap from a friend and figured I can customize it somehow. As you say, I sort of figured that with slower blower speed there will be less heat moved out of the unit and therefore the exchanger will get hotter. Than a friend suggested that I could "plug" one of the four jets ( flames or whatever one calls them) to bring down the BTU/HR input to match the blower speed.
Well - I just don't know about that...... IS THERE a good way to reduce the amount of gas burning? Lower the flames or something?
I will follow your advice and switch the wires and watch and check the rise. Thank you very much,
Peter S., Rochester, NY
peace
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| | static
| "Re(3):Bryant blower speed reduction" , posted Fri 11 Jan 11:45
The gas pressure at the burner manifold needs to be within the range 3.2" to 3.8" of water column, with 3.5" being standard.
Not a fan of plugging burners personally, it just doesn't seem appropriate to me.
If you're at the bottom of the given range for gas pressure and still exceeding the temperature rise, you can swap the brass burner orifices ("spuds") for smaller ones, the orifice size is stamped on each spud. IIRC, larger number = smaller spud. Then with the smaller spuds you can get the gas pressure back up into the given range and be okay on temperature rise as it will be a leaner mix.
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| | psay51
| "Re(4):Bryant blower speed reduction" , posted Sat 12 Jan 08:42
Again - thank you, Static, for your trouble. I won't get to any of this until after this weekend, but I can't wait to see what happens. I hope I can turn to you again if I get stuck.
Thanks,
Peter
peace
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