Furnace making funny noise

radios1 · Oct 18, 2020

Fuddy1952 said:
We used to have oil furnaces, constant maintenance. Once I remember I had transformer door open, checking for high voltage with screwdriver! Across tabs. Fuel ignited blew me across room. I looked in mirror, wife said I looked like Al Jolson. To this day my eyebrows haven't completely grown back.

the flame sensor, or the stack switch should have stopped the fuel after 30 seconds, if they malfunction, you could have a large amount of fuel in the furnace, that's what happened.. a blowback at 30 seconds seems scary, but not enough to be a danger..

Sigarms · Oct 19, 2020

Industrial Toys said:
Do you want me to go to the premise in question and ask about their furnace? It's actually not that far from here. I have no reason to believe the tech I spoke with was trying to mislead me as to the number of speed controlled blowers on a natural gas furnace. He even aluded to the fact that these were simple cheap motors, modified to be speed controlled, but I didn't know enough to mention that. I have a pretty good memory when it comes to conversations that interest me.

Apologies.

The biggest issue with HVAC is terminology. Even with this thread, the motor in question is a prime example of saying one thing, but meaning another. It's a common mistake, even in the industry itself.

If I guy is having a unique problem with a particular part and he calls me, I've found model and serial being required to go to the parts list, and what helps even more after that is a picture of the issue/part. Picture is worth a thousand words. With todays technology, lots of people are even using live video's to help trouble shoot issues in the field when a TSM can't make it to the jobsite if needed.

A constant torque blower motor will have multiple tap settings for blower speed (affecting CFM's the furnace is being set up for), but it's only one motor.

Being that your in Canada, perhaps there is a manufacturer who makes a furnace that has two blower motors inside the furnace, I just have never came across one for a residential application. Now, if you have a ductless mini split, many manufacturers have 3 curcuit board controllers in the outdoor, unit and that's all they call them on the parts list LOL

Sigarms · Oct 19, 2020

radios1 said:
the flame sensor, or the stack switch should have stopped the fuel after 30 seconds, if they malfunction, you could have a large amount of fuel in the furnace, that's what happened.. a blowback at 30 seconds seems scary, but not enough to be a danger..

One reason why you never believe a homeowner when they tell you they only hit the oil primary reset button once

Industrial Toys · Oct 19, 2020

I also clearly remember the tech telling me how disgusted he was with his boss, pushing this hi tech, hi-end crap, while he himself had the most basic and sensible model.

Sigarms · Oct 19, 2020

Industrial Toys said:
I also clearly remember the tech telling me how disgusted he was with his boss, pushing this hi tech, hi-end crap, while he himself had the most basic and sensible model.

Depnding on fuel (electric / oil / gas / LP) some "higher end" HVAC models/systems you can actually see a ROI over time (generally less than 5 years).

That said, per the topic at hand, the United States has now outlawed all HVAC manufacturers from using a basic PSC motors in all residential gas furnaces. Can't blame anyones boss on that.

For myself, I have no qualms and actually prefer a piston metering device for a cooling system, yet they are getting harder and harder to find, instead having to go to TXV's, and newer higher end models using EEV's (electronic expansion valves). Not saying it's right or wrong, just the way the industry is going.

That said, you know who the good HVAC companies are because they will spend both the time and or money to send their service guys to updated training.

It was only about 10 or 15 years ago I knew of some HVAC companies who wouldn't sell ductless mini splits because they were to complicated to service.

What some manufacturers are doing is programing their ECM blower motors and the contractor can't program it themselves (meaning good luck finding something online to actually work). Again, don't agree with it, just the way it's going.

check · Aug 20, 2021

check said:
Hi, guys, problem solved! (I think.)

I finally got a dealer expert to tell me what the problems is, and here is what he said:

"It痴 a piece of foil tape buzzing, he just needs to run his hands around all the taped seams to track it down."

LOL!

kk - update. When I bang on the side of the plenum - the noise stops! I will be opening up the plenum when we get a new AC unit soon, so I can maybe tell what it is that is buzzing.