Bryant 80 plus - no heat - out of ideas

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  #1  
Old 01-11-18, 06:46 AM
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Bryant 80 plus - no heat - out of ideas

Hello all,

I have a Bryant 395CAV, it looks like all the "80 plusĒunits Iíve seen on the internet.

My heater trouble this year started with a burned out blower motor. I replaced the motor, and ever since have had ďcode 33Ē issues. At first, the furnace would only run while the metal cabinet was open. When closed, the furnace cuts off, but the blower keeps running with the error code 33. As if it were not getting enough air. I let it run through the weekend this way until I could call the place I bought the motor to confirm the specs and wiring were correct. And because it was 10į outside. Even with the cabinet cover off, it will still turn itself off periodically, and show the error code 33. At present the code 33 usually starts a minute or so after powering on. Occasionally it will start the burners, but they will only stay on a few minutes. Iíve ordered a new flame roll-out limit switch, which should arrive today. The current one is well-corroded and Iíve manhandled it quite a bit as well. After that Iím out of ideas. Iím concerned that a new switch wonít solve it.

Both motors are 1/3hp 115v, 1075rpm.
The old motor was 4speed, 5.8a
The new motor is slightly more efficient, 3 speed, 5.2a

Filters are fine, not clogged.

Could the motor speed be an issue? The motor shop assured me that a .6a difference would not cause any change.
I am wondering if the speeds of the motors are different enough to create a lack of air.

Would really appreciate any ideas, it's cold inside!
Thanks
 
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Old 01-11-18, 09:32 AM
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Motor running backwards? How much air is coming out of the registers? 3 speeds so try other 2. Proper thing to do is to measure the static pressure.
 
  #3  
Old 01-11-18, 10:59 AM
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Thanks for your reply. The fan is definitely blowing the right direction. The blower is already set to medium. That only really leaves high speed which wouldn't be right (I assume?) even if it works. I can't tell any difference at the vents and have no way to quantify the air flow that I know of.

How does one check for static pressure?
 
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Old 01-11-18, 07:58 PM
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A mamometer is used to measure pressure but your issue sounds like it should be obvious. Does a piece of paper push out from a supply register? Also can measure temperatures. There should be info posted in the furnace saying what maximum temp rise (delta-T). Maybe your heat exchanger or a/c coil is clogged with cat hair. Could be lots of things. Someone on site should narrow down the issue fairly quick.

Also pay attention to the sequence. When cold does it start normally?
 
  #5  
Old 01-11-18, 07:59 PM
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Welcome to the forums.

Unfortunately I've had to use the high speed in some of my replacements as the medium was just slightly to slow to maintain a stable heat rise. You can try the blower on high to see what happens. You aren't going to hurt anything to try it.

I use the heat rise method to gauge blower speed. Measure the incoming return air close to the furnace and the outgoing heated air close to the furnace. Subtract the two. The acceptable heat rise is posted on the model number ID tag near the burner.

Check it again after changing the blower to high speed.
 
  #6  
Old 01-12-18, 03:34 PM
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Awesome, thanks for the ideas guys!
The flame rollout limit switch arrived today (a day late), changed it out and... basically the same result--cut off after running for some random amount of time then displayed code 33. While it was working briefly today I got a little too optimistic. I will try to rewire for high speed tonight, to see if that works. I also thought I might try running the A/C to see if it will give the same code. I also put a call in to an hvac service to come by and clean the coils. I'm not sure how to access them on this unit, as everything is taped up and insulated. I figure at that point I can get a diagnosis from a pro, and at least have the coils cleaned before summer arrives. The PO did have cats, and we've been trying to clean up the various dander stains and clawed-up wood since we've been here. Also, the hvac is in a rather dusty basement, so also I'm sure running it without the cover wasn't a brilliant idea, but it was too cold to not!
 
  #7  
Old 01-13-18, 04:14 PM
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Well, I switched the high and low leads and so far, so good. But having the heater on high is a little crazy, and I'm fearful of the accompanying bill! Should I start looking for a different motor?

I'll try to figure out how to measure heat rise, can I just use an oven thermometer? What does that number tell me, exactly?
 
  #8  
Old 01-13-18, 05:43 PM
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Running the blower on high should not raise the electric rates. It may be a little noisier but will not impact the bill. The heat rise tells you how well your system is working. A meat thermometer will suffice. It needs to be probe style thermometer that can reach into the airflow.
 
  #9  
Old 01-18-18, 09:41 AM
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Well the heater has been running for about 5 days now--cabinet closed--without hiccup on the high blower fan speed.

Despite reassurances, I canít help but think that leaving the fan on high is more of a hack than a fix. I canít imagine it is as efficient as a lower speed. If nothing else, itís much louder as mentioned. By running the heater fan on high, am I merely compensating for an unresolved problem?

I donít have a oven thermometer, so I will have to wait until the next grocery store trip to test the heat rise. Itís at or below 20 here daytime right now, so I donít want to mess with something thatís currently workingóIím just glad to have heat. But, when the weather warms-up just a little Iíd like to investigate further.

We skipped the coil cleaning for now to save a little money, and since we're not even sure it's a problem. If I can figure that part out I'd like to do that myself too before the cooling season starts.

I appreciate the feedback and suggestions here, hope it helps someone else in the future!
 
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