Humming Noise In A Brand New Furnace

 
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Old 01-27-2012, 08:13 PM   #1
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Humming Noise In A Brand New Furnace


Had a new furnace installed , when the unit shuts off there's a humming noise coming from the transformer , my havoc guy says its the electric current from the plug and I should have electrician change the breaker ?

Asked my electrician today and he said he never heard of that solution , any of you hvac guys come across this ? Is there a fix ?

Thanks in advance
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Old 01-27-2012, 08:38 PM   #2
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Re: Humming Noise In A Brand New Furnace


My aquastat hums every now and then. I just smack it once and it stops.

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Old 01-27-2012, 08:39 PM   #3
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Re: Humming Noise In A Brand New Furnace


Transformers can buzz. It is because of the 60Hz current going through them is making the laminationa in the core strike each other because of the magnetic flux. You might be able to isolate the transformer or the box the transformer is in and this might isolate the humming. Rubber padding between the transformer and the furnace might dampen the humming.
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Old 01-28-2012, 04:57 AM   #4
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Re: Humming Noise In A Brand New Furnace


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Transformers can buzz. It is because of the 60Hz current going through them is making the laminationa in the core strike each other because of the magnetic flux. You might be able to isolate the transformer or the box the transformer is in and this might isolate the humming. Rubber padding between the transformer and the furnace might dampen the humming.
Yep, 60 hertz hum is a common problem. And a thin piece of rubber often takes care of it.
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Old 01-28-2012, 08:41 AM   #5
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Re: Humming Noise In A Brand New Furnace


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Originally Posted by Five Star View Post
Had a new furnace installed , when the unit shuts off there's a humming noise coming from the transformer , my havoc guy says its the electric current from the plug and I should have electrician change the breaker ?

Asked my electrician today and he said he never heard of that solution , any of you hvac guys come across this ? Is there a fix ?

Thanks in advance
Actually, 60HZ transformers should not hum. They are designed and must meet the standards issued for 60HZ operation. PUTTING VIBRATION ISOLATORS ON THE TRANSFORMER MOUNT ONLY REMOVES THE SYMPTOM...IT DOES NOT ADDRESS THE CAUSE.

Humming is actually a sign of possible problems with either the supply voltage, cycle rate, or even the transformer itself. The voltage being supplied should be checked (+or- 10% of rated primary (supply side) voltage should be present). Make sure the taps are correctly wired for the voltage being utilized on the primary side of the transformer. If the supply side voltage is not correct, this is your problem and your electrician should be able to isolate whether the cause is local or from the utility.

If the primary or supply voltage to the transformer is correct...check the secondary or load side of the transformer. Voltage should be 24 volts...give or take a few percentages. If it is not and the supply or primary voltage checks out replace the transformer.

ALSO....TRANSFORMERS INSTALLED AT THE FACTORY HAVE A VA RATING. MAKE SURE THERE IS NOT MORE LINEAR FEET OF TSTAT WIRE THAN ALLOWED!!! MANY INSTALLERS OVERLOOK THIS. FOR EXAMPLE MANY MANUFACTURERS LIMIT THE AMOUNT OF TSTAT WIRE TO 100FEET. IF YOUR INSTALLER GOES OVER THIS YOU WILL MOST DEFINITELY GET A HUMMM AND POSSIBLE OPERATIONAL PROBLEMS. IF THIS IS THE CASE HAVE YOUR INSTALLERS REPLACE THE FACTORY TRANSFORMER WITH A REPLACEMENT WITH ADEQUATE VA.
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Old 01-28-2012, 09:48 AM   #6
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Re: Humming Noise In A Brand New Furnace


Nothing is perfect. And transformers can hum if the laminations aren't fully glued to each other or the windings aren't tight enough to hold them together. Usually it happens with age, but sometimes right out of the box. I doubt the supply current is wrong if it is hooked in to the same breaker box as everything else.
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Old 01-28-2012, 09:54 AM   #7
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Re: Humming Noise In A Brand New Furnace


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Originally Posted by CAS View Post
Actually, 60HZ transformers should not hum. They are designed and must meet the standards issued for 60HZ operation. PUTTING VIBRATION ISOLATORS ON THE TRANSFORMER MOUNT ONLY REMOVES THE SYMPTOM...IT DOES NOT ADDRESS THE CAUSE.

Humming is actually a sign of possible problems with either the supply voltage, cycle rate, or even the transformer itself. The voltage being supplied should be checked (+or- 10% of rated primary (supply side) voltage should be present). Make sure the taps are correctly wired for the voltage being utilized on the primary side of the transformer. If the supply side voltage is not correct, this is your problem and your electrician should be able to isolate whether the cause is local or from the utility.

If the primary or supply voltage to the transformer is correct...check the secondary or load side of the transformer. Voltage should be 24 volts...give or take a few percentages. If it is not and the supply or primary voltage checks out replace the transformer.

ALSO....TRANSFORMERS INSTALLED AT THE FACTORY HAVE A VA RATING. MAKE SURE THERE IS NOT MORE LINEAR FEET OF TSTAT WIRE THAN ALLOWED!!! MANY INSTALLERS OVERLOOK THIS. FOR EXAMPLE MANY MANUFACTURERS LIMIT THE AMOUNT OF TSTAT WIRE TO 100FEET. IF YOUR INSTALLER GOES OVER THIS YOU WILL MOST DEFINITELY GET A HUMMM AND POSSIBLE OPERATIONAL PROBLEMS. IF THIS IS THE CASE HAVE YOUR INSTALLERS REPLACE THE FACTORY TRANSFORMER WITH A REPLACEMENT WITH ADEQUATE VA.
This post has be re-posted b/c one of the above is your problem. Control transformers in HVAC equipment(60HZ) will not hum UNLESS THERE IS A PROBLEM. To those in this forum pay close attention to the trade the posters are part of. In the HVAC forum it makes logical sense to give more consideration to those involved in the trade such as Doc, Flash, Beenthere, and so on. Folks in visiting the HVAC forum are looking for answers not assumptions or guesses.
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Old 01-28-2012, 10:31 AM   #8
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Re: Humming Noise In A Brand New Furnace


So you are saying HVAC transformers are perfect and cannot hum and cannot be defective? That it always has to be a problem somewhere else? That it is totally out of the realm possibility that it is the transformer and not something else?

I have a gas fired modine heater that the transformer hums on. The T stat wire is about 30' long. As long as it has power to it it hums. Is this a problem?

Cause I have 3 more that do the exact same thing and are set up the same way. So this cannot possibly be the transformer and has to be the way the pro set them up?
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Old 01-28-2012, 10:50 AM   #9
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Re: Humming Noise In A Brand New Furnace


Quote:
Originally Posted by CAS View Post
Actually, 60HZ transformers should not hum. They are designed and must meet the standards issued for 60HZ operation. PUTTING VIBRATION ISOLATORS ON THE TRANSFORMER MOUNT ONLY REMOVES THE SYMPTOM...IT DOES NOT ADDRESS THE CAUSE.

Humming is actually a sign of possible problems with either the supply voltage, cycle rate, or even the transformer itself. The voltage being supplied should be checked (+or- 10% of rated primary (supply side) voltage should be present). Make sure the taps are correctly wired for the voltage being utilized on the primary side of the transformer. If the supply side voltage is not correct, this is your problem and your electrician should be able to isolate whether the cause is local or from the utility.

If the primary or supply voltage to the transformer is correct...check the secondary or load side of the transformer. Voltage should be 24 volts...give or take a few percentages. If it is not and the supply or primary voltage checks out replace the transformer.

ALSO....TRANSFORMERS INSTALLED AT THE FACTORY HAVE A VA RATING. MAKE SURE THERE IS NOT MORE LINEAR FEET OF TSTAT WIRE THAN ALLOWED!!! MANY INSTALLERS OVERLOOK THIS. FOR EXAMPLE MANY MANUFACTURERS LIMIT THE AMOUNT OF TSTAT WIRE TO 100FEET. IF YOUR INSTALLER GOES OVER THIS YOU WILL MOST DEFINITELY GET A HUMMM AND POSSIBLE OPERATIONAL PROBLEMS. IF THIS IS THE CASE HAVE YOUR INSTALLERS REPLACE THE FACTORY TRANSFORMER WITH A REPLACEMENT WITH ADEQUATE VA.
Quote:
This post has be re-posted b/c one of the above is your problem. Control transformers in HVAC equipment(60HZ) will not hum UNLESS THERE IS A PROBLEM. To those in this forum pay close attention to the trade the posters are part of. In the HVAC forum it makes logical sense to give more consideration to those involved in the trade such as Doc, Flash, Beenthere, and so on. Folks in visiting the HVAC forum are looking for answers not assumptions or guesses.
The above has again been reposted. I hope Five Star has success in eliminating the problem. We have run across this many times, mostly on older equipment, and when we leave the problem is fixed. This is what I and others here do for a living and therefore we speak and give advice from a point of experience. Let us know how it works out Five Star!!
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Old 01-28-2012, 12:01 PM   #10
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Re: Humming Noise In A Brand New Furnace


ouch!

Leo's description of delaminating core is also one that I've come across. I'm not sure if it's 'truly' a problem, I would guess that the efficiency of the step down transformer would be in question, but w/ such small currents needed, may not be an issue. That hum sure is irritating though!
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Old 01-28-2012, 06:00 PM   #11
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Re: Humming Noise In A Brand New Furnace


5-star shouldn't change anything. He just bought the product, and should he touch anything, it can give the hvac installers an excuse to wash their hands of the situation.

We don't know exactly how things were said betwen 5-star and the installer, but, "it's a supply voltage thing, get the electrician to fix it" is not an acceptable answer. It wouldn't have taken much to simply change the transformer, and see what happens.

Sometimes it baffles me to see how people tend to shift the blame, instead of addressing the issue.
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Old 01-28-2012, 07:02 PM   #12
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Re: Humming Noise In A Brand New Furnace


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5-star shouldn't change anything. He just bought the product, and should he touch anything, it can give the hvac installers an excuse to wash their hands of the situation.

We don't know exactly how things were said betwen 5-star and the installer, but, "it's a supply voltage thing, get the electrician to fix it" is not an acceptable answer. It wouldn't have taken much to simply change the transformer, and see what happens.

Sometimes it baffles me to see how people tend to shift the blame, instead of addressing the issue.
Your absolutely right , thank you , it's really not the electricians problem , I forwarded some of your guys replys , and I appreciate all of your guys responses !

Thanks again
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Old 01-28-2012, 09:28 PM   #13
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Re: Humming Noise In A Brand New Furnace


I've only come across a humming transformer when there was a problem such as it was going out/weak or where there was a miswiring issue.

No, a transformer should never hum.
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Old 01-29-2012, 07:07 AM   #14
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Re: Humming Noise In A Brand New Furnace


Quote:
Originally Posted by CAS View Post
. To those in this forum pay close attention to the trade the posters are part of. In the HVAC forum it makes logical sense to give more consideration to those involved in the trade such as Doc, Flash, Beenthere, and so on. Folks in visiting the HVAC forum are looking for answers not assumptions or guesses.
I am sorry but I completely disagree with YOUR logic here. A good many of us have done some HVAC work in our lives, even though we are not really listed as in the trade.

Just because you are in the trade, you don't have all the answers & neither do we. One could do alot of installation work etc, and not be that good at troubleshooting.
I myself have given some good advice in this section from my experience with it through out my life. And I am sure there are many others, like Leo, for example. Anyone can get in the trade,it doesn't mean you are a GURU....

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Old 01-29-2012, 09:23 AM   #15
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Re: Humming Noise In A Brand New Furnace


I took jr high and high school courses in electronics. While I was in High school I had to go to college because they ran out of stuff to teach me. Then I went to college for my electrical engineering degree. So I might know a few things about electronics and transformers.

Plus I use to build electronic things for fun. It's not like it is out of my field.
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Old 01-29-2012, 09:29 AM   #16
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Re: Humming Noise In A Brand New Furnace


All transformers hum, I buy 12DC and 16/24AC in bulk and I can tell ya every once in a while you will get a real hum-dinger and I just toss it in the bin.

If the hum is loud have the HVAC guy replace the transformer, easy-peasy.
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Old 01-29-2012, 11:00 AM   #17
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Re: Humming Noise In A Brand New Furnace


Not all transfromers hum. Again, I've only come across it in hvac control transformers when there was a problem. Bigger transformers, yes. More often than not without any problem.

You are talking about magnorestriction, the metal core made up of sheets of metal which extend, expand and contract, and thus chatter against one another when voltage is applied to the metal.
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Old 01-29-2012, 11:00 AM   #18
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Re: Humming Noise In A Brand New Furnace


In the op's case the transfomer should have been changed, imo.
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Old 01-29-2012, 11:15 AM   #19
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Re: Humming Noise In A Brand New Furnace


Nice post, as I now know a little bit more about transformers. I dd not know the reason for the humming.
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Old 01-29-2012, 11:15 AM   #20
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Re: Humming Noise In A Brand New Furnace


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I am sorry but I completely disagree with YOUR logic here. A good many of us have done some HVAC work in our lives, even though we are not really listed as in the trade.

Just because you are in the trade, you don't have all the answers & neither do we. One could do alot of installation work etc, and not be that good at troubleshooting.
I myself have given some good advice in this section from my experience with it through out my life. And I am sure there are many others, like Leo, for example. Anyone can get in the trade,it doesn't mean you are a GURU....

CAS is strange, no doubt about that, but he is right. I do not see how simply doing "some" hvac work means you are a studied professional.

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