Help. Can't find 24v fuse in bryant oil furnace


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Old 07-17-09, 04:29 PM
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Help. Can't find 24v fuse in bryant oil furnace

I know nothing about furnaces or wiring. However, I just had a thermostat installed and when I go to turn it on, nothing happens. I called the thermostat company and they said the fuse was blown.

And they told me to locate it on the oil furnace and I could go to an automotive place or anywhere to buy the same one and replace.

The problem is, I can not find the fuse. Any idea where it typically is on a Bryant oil furnace, or any furnace for that matter?

I found a circuit board but dont see any fuses! HELP PLEASE!
 
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Old 07-17-09, 05:44 PM
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Well, look carefully at every diode thingy and everything. And see if you see the lettering like 3A. It's concievable you do not even have a fuse.

Who put that stat in without trying the furnace? ?????

Make sure circuit breaker(or fuse) is not tripped or burned out. Make sure that the blower door on the furnace is on, because there will be an electrical safety switch the blower door must push in.

If all this checks out, then you can put a jumper wire between the R and W terminals on your 24 volt terminal strip in the furnace, to temporarily bypass the thermostat, to see if then the furnace starts up. If it does, the stat wires are messed up somehwere, not hooked up right, or stat not programmed right or in a run mode, or maybe it needs batteries, or dip switches inside it are not set to the right settings.
 
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Old 07-17-09, 10:05 PM
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Did the furnace work ok before the themostat was changed? if yes, they are on the hook to make your furnace work again. The fuses look like the ones that you see in cars. A little plug in thing.
 
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Old 07-18-09, 06:25 AM
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thanks for the posts. It is a weird situation, I just bought the house. the thermostat was put in after the inspection as part of the deal. Since there was so many things to check when I came back for the re inspection I remember the guy showing me how to work the thermo but am not sure if I heard the thing kick on.

The house was going into foreclosure, I tried to call teh seller but his line is disconnected. He was in HVAC but did not seem a financially stable person, I have little hope of seeing him again.

It had worked before the thermostat was put in place, and its a brand new AC.

I looked for something plastic and only found three things but I looked up their part numbers online and they are just contacts.

I read somewhere on here to try and replace the transformer?

The person who told me to replace the fuse was the thermostat company that I called. They had me touch two wires together and nothing happened. He said blown fuse.

I checked all the breakers and the AC plugs. I do not know much about wiring/HVAC.

Is it time to call someone?
 
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Old 07-18-09, 10:29 AM
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Probably, unless you want to post some pics and we'll see if we can find a solution. Question- is this a heat/cool system or heat only?
 
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Old 07-18-09, 02:10 PM
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Originally Posted by daddyjohn View Post
Probably, unless you want to post some pics and we'll see if we can find a solution. Question- is this a heat/cool system or heat only?
heat and cool.

I will try and figure out how to post pics.

And ill start by calling bryant heating and cooling on monday
 
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Old 07-18-09, 02:25 PM
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Can I safely assume that niether the heating nor the cooling work? See if you can take the thermostat apart and to see if it has an Rc terminal and an Rh terminal where the wires are connected. Also, look to see if the jumper between Rc and Rh was removed. When you have cooling iwth oil heat, there are 2 control transformers that have to be kept separated from each other. If they are not, they will be toast.
 
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Old 07-18-09, 06:11 PM
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Originally Posted by myfurnacesucks View Post
The person who told me to replace the fuse was the thermostat company that I called. They had me touch two wires together and nothing happened. He said blown fuse.

I checked all the breakers and the AC plugs. I do not know much about wiring/HVAC.

Is it time to call someone?
Yes, call someone.

Often, 24-V xfmrs are inherently protected against shorts and overloads by their internal impedance. In which case, there may be no fuse.

If there is a fuse, and it blew, it is likely because there is another problem. Fuses usually blow because of another problem.
Doug
 
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Old 07-18-09, 07:38 PM
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I read fast so may have missed that this has been mentioned, forgive me before you shoot me.

If no power to the furnace, make sure you have located all service switches, on side of furnace, at top of stairs, and sometimes next to outside basement entrance. There may also be a fuse mounted right on the service switch cover next to the switch. Usually this would be on the service switch next to the furnace.

As mentioned before, fuses go for a reason. But a hidden service switch is an easy one to miss.

sorry to interrupt
Bud
 
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Old 07-19-09, 04:47 PM
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so I found there was no power from the transformer so I bought a new one.

Hooked it up and turned the power back on. The air started blowing for about a minute!!!

Then it stopped.

I go to the furnace and see wisps of smoke and a smell coming from the new transformer. OOPS! guess it is now time to call someone...
 
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Old 07-19-09, 06:34 PM
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Transformers have a one shot thermistor built in. When it overheats and blows, there goes the transformer. My money is on a short circuit, either in the wiring or at the new thermostat.
 
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Old 07-20-09, 08:10 AM
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Originally Posted by myfurnacesucks View Post
And they told me to locate it on the oil furnace ....
There we go! Read below!!!

From daddyjohn:
Can I safely assume that niether the heating nor the cooling work? See if you can take the thermostat apart and to see if it has an Rc terminal and an Rh terminal where the wires are connected. Also, look to see if the jumper between Rc and Rh was removed. When you have cooling iwth oil heat, there are 2 control transformers that have to be kept separated from each other. If they are not, they will be toast.
 
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Old 07-20-09, 10:16 AM
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I hope the transformer in the oil burner primary control isn't toast. The entire control would have to be replaced $$$$$
 
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Old 07-20-09, 05:01 PM
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Originally Posted by ecman51` View Post
There we go! Read below!!!

From daddyjohn:
A lot of that is over my head! lol


Originally Posted by daddyjohn View Post
I hope the transformer in the oil burner primary control isn't toast. The entire control would have to be replaced $$$$$
How much money?

I am having someone come look at it tomorrow. thanks all for the help! greatly appreciated
 
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Old 07-20-09, 07:22 PM
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I haven't priced primary controls in several years but $300 for the part alone would not surprise me.
 
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Old 07-21-09, 05:38 PM
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Originally Posted by myfurnacesucks View Post
A lot of that is over my head! lol
It's actually very simple. The connections in the thermostat are labeled with maybe 6 or 7? letters, at terminal connections inside.

Two of those letters might be Rh and Rc (for heat and cool). He was saying in his reply post to you that if you have an oil furnace - and you do - that these cannot be jumpered together in the stat, because oil furnaces set up with a/c use 2 transformers. (To not confuse you, the transformers are not in the thermostat -so don't bother looking for those.).

Just open the thermostat and look to see if there is a factory bonding wire that joins Rh to Rc - that's all. That should be easy enough. If there is one, according to DJ, you would remove that. {If you monkey with connections, always shut off the power to the furnace.}

And if you cannot do that, at least bring this up to the service man if he comes out.
 
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Old 07-22-09, 05:03 AM
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Problem is someone else installed the stat. If he touches it, bye bye warranty or gettign an installation screwup covered.
 
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Old 07-22-09, 07:19 AM
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Originally Posted by ecman51` View Post
It's actually very simple. The connections in the thermostat are labeled with maybe 6 or 7? letters, at terminal connections inside.

Two of those letters might be Rh and Rc (for heat and cool). He was saying in his reply post to you that if you have an oil furnace - and you do - that these cannot be jumpered together in the stat, because oil furnaces set up with a/c use 2 transformers. (To not confuse you, the transformers are not in the thermostat -so don't bother looking for those.).

Just open the thermostat and look to see if there is a factory bonding wire that joins Rh to Rc - that's all. That should be easy enough. If there is one, according to DJ, you would remove that. {If you monkey with connections, always shut off the power to the furnace.}

And if you cannot do that, at least bring this up to the service man if he comes out.
There is no factory bonding between Rh and Rc. there is no wire even going into RC.

I am thinking the board may be bad or is wired wrong??

Either way, the fix is over my head, I am going to have someone come look at it. thanks all
 
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Old 07-22-09, 08:40 AM
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You have heating and cooling but there is no wire on Rc at the stat? It's wired wrong.
 
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Old 07-22-09, 08:55 AM
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Originally Posted by myfurnacesucks View Post
Either way, the fix is over my head, I am going to have someone come look at it. thanks all
If you ever want to learn how to DIY, think positive, that with some advice and tips from others, that you might be able to conquer what ever dilemma confronts you.

I maybe was born with that attitude. And because of that, have been able to fix many things where I had no previous experience in it. And it feeds on itself. Once you learn basics for one piece of mechanical equipment, you start to understand certain logic in mechanical and electrical functions. And this can help you with even other unrelated pieces of equipment.

My brother in-law is one of those who never gets his hands dirty, and is lucky he knows what a wrench does. But I instructed him over the phone how to test the compressor, and he did, with the $3 stocking stuffer Harbor Freight multi-meter I gave him at Christmas. And he went out and bought an overload-realy assembly and replaced it himself!

And not only did he save money - he was proud of himself that he was actually able to do something like that!
 
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Old 07-25-09, 06:13 AM
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the guy came and looked at it. after 3 hours he still could not figure it out.

He got the blower running now, but the outside part still wont kick on. And he is saying its a bad board (brand new).

So he is coming back today with a new board. I am crossing my fingers but stil doubtfull.
 
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Old 07-28-09, 06:30 AM
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He can't just bypass the board to see if the outdoor unit will run? What about the RC connection in the stat I asked about? if Rc is not powered the outdor unit won't run.
 
 

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