โFeb-29-2016 04:01 AM
โMar-09-2016 03:16 AM
trailrider wrote:
REPLACE THE MOTOR!!!
Most likely all of your furnace problems will disappear
โMar-08-2016 08:45 PM
โMar-08-2016 05:39 PM
โMar-08-2016 05:22 PM
OregonTravelers wrote:Don't know what to tell you. You have 2 rv techs here telling you motor but your not listening.
Still having a problem with the furnace. The circuit board was replaced previously and I yesterday, I replaced the thermostat, but the furnace still cycles on and off and then trips the circuit breaker.
Now what?
โMar-08-2016 05:04 PM
โMar-08-2016 05:01 PM
โMar-02-2016 04:06 PM
โMar-02-2016 10:17 AM
bid_time wrote:Chris Bryant wrote:You know Chris, I respect your opinion a lot. But there is no call to be snarky with the unabridged dictionary thing.
Y'all can talk about the thermostat as much as you want, but I could replace it with a Morse code key and key the unabridged Oxford English Dictionary and not trip that breaker. This furnace is not an air conditioner. Short cycling cannot and will not cause excessive current draw- certainly not (at 15 amps) nearly double the rated draw (8 amps).
When you have a system that does not work, and you know there is a fault, you fix that fault before anything else. Now I wouldn't do anything before actually measuring the current draw of the motor, but there really is not that much more that it could be.
We have a difference of opinion, but I don't think an overdraw by the motor is causing the furnace to cycle. But I can envision the motor overheating by continuous cycling, especially in a furnace with the burner on. After that all types of things could happen. Peace!
โMar-02-2016 09:48 AM
Chris Bryant wrote:You know Chris, I respect your opinion a lot. But there is no call to be snarky with the unabridged dictionary thing.
Y'all can talk about the thermostat as much as you want, but I could replace it with a Morse code key and key the unabridged Oxford English Dictionary and not trip that breaker. This furnace is not an air conditioner. Short cycling cannot and will not cause excessive current draw- certainly not (at 15 amps) nearly double the rated draw (8 amps).
When you have a system that does not work, and you know there is a fault, you fix that fault before anything else. Now I wouldn't do anything before actually measuring the current draw of the motor, but there really is not that much more that it could be.
โMar-02-2016 08:54 AM
DFord wrote:
So far, I've seen no indication that anyone has any idea of why the furnace is short cycling when it should be off. I've given a suggested procedure to begin troubleshooting but everyone just wants to swap parts. All the parts changed out so far has just been a waste of money and nothing has been accomplished.
I've studied the wiring diagram and see the thermostat only has two wires going to it. When the thermostat calls for heat, those two wires are connected. When it's not, those wire are disconnected. Until you know why the furnace is short cycling, the reason for the breaker tripping is a secondary symptom of the actual problem. A bad blower motor could not possibly cause the furnace to short cycle.
I would disconnect the thermostat and use a jumper to run the furnace for a couple of minutes. Then remove the jumper and see what happens. The furnace should not reignite again. What we need to know is if the thermostat is causing the furnace to short cycle. The OP stated the furnace reignited when it was short cycling. If that's the case, the thermostat is the cause of the problem. If only the blower is short cycling, the problem is probably the "relay.""RELAY" description from the furnace manual wrote:
Simple. IF the motor is defective(IT IS in this case), the motor when it starts to draw too many amps will overheat and slow down. That causes 2 things. 1. The sail switch will probably open and shut the burner down. 2. The slower speed causes the burner case to also overheat and may cause the Limit switch to then trip. You can argue all you want about the parts replaced. In this case ALL the pertinent parts have been replaced and the only part left is the motor which is the ONLY part that will cause the CB to trip without a direct short. As with what Chris stated---Thermostats NEVER and rarely cause operational problems. ALL they do is open and close 2 wires to the furnace, nothing else. Doug
โMar-02-2016 06:58 AM
DFord wrote:
So far, I've seen no indication that anyone has any idea of why the furnace is short cycling when it should be off. I've given a suggested procedure to begin troubleshooting but everyone just wants to swap parts. All the parts changed out so far has just been a waste of money and nothing has been accomplished.
I've studied the wiring diagram and see the thermostat only has two wires going to it. When the thermostat calls for heat, those two wires are connected. When it's not, those wire are disconnected. Until you know why the furnace is short cycling, the reason for the breaker tripping is a secondary symptom of the actual problem. A bad blower motor could not possibly cause the furnace to short cycle.
I would disconnect the thermostat and use a jumper to run the furnace for a couple of minutes. Then remove the jumper and see what happens. The furnace should not reignite again. What we need to know is if the thermostat is causing the furnace to short cycle. The OP stated the furnace reignited when it was short cycling. If that's the case, the thermostat is the cause of the problem. If only the blower is short cycling, the problem is probably the "relay.""RELAY" description from the furnace manual wrote:
Don. I have been pondering the same thing. I can understand that excessive current draw of blower motor would trip the circuit breaker. But I don't understand why that would cause the furnace to cycle on and off like it does before the breaker is tripped.
I like your suggestion of trying to by-pass the thermostat and see if the problem continues.
Thanks for the insight.
Carl
โMar-02-2016 06:29 AM
"RELAY" description from the furnace manual wrote:
โMar-02-2016 06:14 AM
Chris Bryant wrote:
Y'all can talk about the thermostat as much as you want, but I could replace it with a Morse code key and key the unabridged Oxford English Dictionary and not trip that breaker. This furnace is not an air conditioner. Short cycling cannot and will not cause excessive current draw- certainly not (at 15 amps) nearly double the rated draw (8 amps).
When you have a system that does not work, and you know there is a fault, you fix that fault before anything else. Now I wouldn't do anything before actually measuring the current draw of the motor, but there really is not that much more that it could be.
โMar-02-2016 06:10 AM
bid_time wrote:Sluggo54 wrote:That's a very good suggestion. If the "range" is set to low it could cause the cycling. That furnace should not be instantaneously cycling on and off. That could possibly make something get to hot and make the circuit breaker blow.
Some thermostats have adjustable "range" - i.e., it can be set to raise the temp 1 degree, two degrees, or three. It may be sensitive enough that a slight change in temp could cause problems. It is no cost to open it or take the cover off and find out.
โMar-02-2016 04:44 AM