Just venting...Idiot heating guys

18 years ago

I've had a Bryant gas furnace for about 12 years (when they installed gas in my neighborhood). The installing/servicing company was a real piece of work, I finally terminated them a couple of years ago after a run-in regarding the air conditioner.

The Bryant has never bee tremendously reliable, tending to drop off line with some goofy blinky light error code. There have been recalls on both the gas valve and the processor board over the years.

This brings me to this mornings problem. Woke up to a cold house. Go down stairs, furnace dead. No signs of electrical power, thermostat's battery backup is saying NO PWR. Great check breakers. Fine. Check the voltage at the furnace, good.

Open the blasted thing up. Power inside is present.

Now I open up the blower housing. This is where Bryant relocated the control board during the recall. The work was done by the bozo contractor. I had already griped about this installation for several obvious reasons. They ran the wiring hardness through a raw sheet metal hole with no sort of bushing or other protection. Also they only could get one screw into the thing to secure it. And now that the board is a foot further away than where the AC and thermostat is, rather than replacing the 2' wire inside the cabinet with a 3' one, they wirenutted extensions to both the AC and the thermostat just dangling inside the cabinet without any protection (at least this gave me a convenient place to check for voltage after the disconnect).

Well now I start tracing the AC and get down to where the transformer picks of the low voltage...hey what's this thing. There's a piece of electrical tape covering something. I peel it off and it's a contact switch that is supposed to kill the power when the cover to the fan housing is removed, except that the fact that they've misinstalled the thing means it doesn't make contact with the cover with the one screw in place, so they just defeated it with a piece of tape which has after several years worked loose enough to allow the switch to open

ARRRRGGGGGHHHGHGHAHGHHGHG!

These clowns are still haunting me.

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Comments (8)

bob_brown
18 years ago
PCB's do not belong in furnaces. They fail for many reasons including Carrier's. They can easily reside within the blower section of the furnace if designed properly. I have extensive experience with PCB's, and only see troubles for future systems. A PCB is a mini computer that should be treated as a computer. No one seems to see the need to do so. Manufacturers seem to believe that the consumer knows better, but as in many things, they do not care. If I appear to be down on manufactors, I see both sides of the story. The PCB needs more isolation in most systems.
zl700
18 years ago
???????????

Bring back vacuum tubes for TV's also!

What was that all about?
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Ron Natalie
Original Author
18 years ago
This thing is in the blower housing, actually in the return plenum ahead of the fan, inside a box that is *SUPPOSED* to be sealed off from the airflow by the installation of the plenum cover (which seals off the open side of the box holding the circuit board at the same time as it seals the plenum AND ... if installed properly and not defeated with electrical tape... push the safety switch in).
mr_havac
18 years ago
"What was that all about?"
Oh you ain't seen nothing yet zl700! Stay tuned, you're in for a treat! LOL
baymee
18 years ago
lol
bob_brown
18 years ago
I fix many systems that have mechanical switches that seem to keep on working. They do not use a pcb. I have replaced just about every common board and sometimes multiple times within a year.(Carrier)When a homeowner has to repair a PCB multiple times a year,It just aint right.
PCB's are miniture computers without the normal protection provided to computers.
mr_havac
18 years ago
"When a homeowner has to repair a PCB multiple times a year,It just aint right."
You're absolutely correct. After the second one did you think of looking beyond the board? Voltage spikes, voltage dips, transformer problem? Plus or minus 10% of a vooltage swing doesn't give you much to work with when you're dealing with 24 volts. And it hard to check accurately with that $5.98 Radio Shack multi meter too! Mechanical switches can fail closed just as well as open. I wouldn't be surprised if there are hundreds of limit switches out there that are failed closed as we speak. They just haven't had to be used yet, but when a blower fails and the furnace burns the house down the average local yocal fire investigator probably doesn't even think about that as the cause. Thats why mechanical switches are very undependable. I'll take a fusible link anyday. Then we have to keep people from non heating dominant areas from putting jumpers on a melted link instead of figuring out the problem and replacing the link!
mike13
18 years ago
Bob,

I do really enjoy your statements as they are usually just downright funny. And, occasionally I'll respond as I'm about to do here.

PCBs are NOT mini-computers. They are simply "printed circuit boards" that are used to mechanically support & electrically connect electronic components. Usually made of materials like FR-4 (woven glass & epoxy) along with copper foil these PCBs by themself have very, very low failure rates. They easily meet Six Sigma standards if you are familiar with that.

It is the components placed on the PCBs which typically fail. But I imagine the Bryant engineers know the temperature, voltage, etc ratings of each individual component that goes onto the control board (temp ratings are typically 0 to 70 degrees C for consumer use, -40 to +85 degrees C for industrial use) and don't spec that for installations where temperatures get outside the range.

Given it is a control board it probably comes from Honeywell or someone like that & it comes with its own specs which the Bryant engineers then approve for use within their equipment within a given environment.

Mini-computers is mostly an obselete term that described a class of computers in the middle range, somewhere between mainframes & PCs. Originated by DEC & others like Data General, Wang, Prime, etc joined in that market those companies pretty much disappeared in the late 80's & 90's.

You don't need a highly-controlled environment like computer rooms/labs for the typical control boards to operate as they should as you suggest above. Most microprocessors/microcomputers (like Intel, Motorola, etc) operate fine in the HVAC space.

As mentioned above, the primary problem appears to be the "bozo" installation contractor. Maybe that is why you stated "I have replaced just about every common board and sometimes multiple times within a year.".