Bryant propane heater can't possibly be wired reversed (red LED blinks constantly)

With that clogged air filter, I'd be thinking bad thermal limit switch. I replaced one this year in my own furnace, and one about a week later for a customer.

- . Christopher A. Young Learn about Jesus

trader_4 wrote, on Mon, 22 Dec 2014 08:21:13 -0800:

OK. Fair enough. I haven't looked hard enough mainly because I really don't think the problem is a reversed polarity on the AC circuit.

First off, the thing is AC, so, "most" AC items don't care whether the hot or neutral are reversed anyway; but more importantly, nothing was done to reverse the hot and neutral.

Looking at my pictures, clearly the line voltage comes in right at the middle, from the overhanging flexible metal BX cable:

So, I'll pop off the cover of the box on the inside of that connection - but - really - that will just tell me what I already know must be the case - which is that the AC "line voltage" isn't reversed.

But, I'll check it - and report back - with pictures.

CY: Hello! BX cable on top, to small box. Earth to Danny!

CY: I've seen reversed polarity, and also open grounds.

CY: Well, in that case, the job is completed, and you can post about it.

- . Christopher A. Young Learn about Jesus

trader_4 wrote, on Mon, 22 Dec 2014 08:21:13 -0800:

I agree that hot and neutral *can* be reversed, but, from a practical standpoint, other than the safety of two-wire grounded items, it makes no difference.

So, when they're talking polarity reversal in the continuous-blink scenario, I wonder if they're talking about the DC voltage, where polarity can make a huge difference.

I doubt either one was reversed, simply because nothing was touched, but, methinks they may be talking DC and not AC anyway.

Nonetheless, I'll pop that box off in the middle of the furnace and measure the voltages (yes, I know what all the colors mean, including white, black, red, if it's there, and green or bare).

I didn't check if it's 220V, but that just means there will be two hots and a neutral, instead of a hot and a neutral.

No, they are talking about polarity reversed at the incoming AC, ie hot and neutral. How would you ever get DC reversed on the circuit board?

It's nothing to do with airflow. He says he gets the flashing from the LEDs indicating a fault as soon as power is applied, before there is even a call for heat.

We'd expect nothing less from the professional you are.

- . Christopher A. Young Learn about Jesus

On my own furnace, I did get a fault code when it powered up, and turned out to be a bad limit.

So my personal experience is.....

- . Christopher A. Young Learn about Jesus

Stormin Mormon wrote, on Mon, 22 Dec 2014 12:49:48 -0500:

I gathered the testing equipment:

I removed the cover of the inlex box from the BX cable:

I separated the hot (black), neutral (white) & ground (green):

Turning power on, I tested neutral to ground at 0 volts AC:

Turning power on, I tested hot to ground at nominally 120VAC.

Turning power on, I tested hot to neutral at nominally 120VAC.

I turned the power off, and reconnected the wires as before.

If the power is reversed, it's not at the inlet BX cable connection to the unit.

What I mostly want to find is the big red button that says "reset", but I don't see it. I see a bunch of smaller limit resets, all of which I've pressed already.

Stormin Mormon wrote, on Mon, 22 Dec 2014 11:31:41 -0500:

The grounds seem good, tested from green to the metal case.

I suggest you read my previous post that explains how the flame sensor circuit works.

You can lead a horse to water......

Mark

trader_4 wrote, on Mon, 22 Dec 2014 08:37:51 -0800:

The incoming power, at least at the BX cable coming into the furnace, is not reversed, but, clearly "something" is wrong, so I do appreciate the advice as to what to look for.

A few things I did in the meantime, which "may" have changed the situation is that I opened up all the vents in the house, most of which had been closed for some reason (almost certainly since last winter), which means the vent airflow was certainly stifled.

I opened all the suckers:

And, I ascertained that there is no V-shaped filter in the top (left) side of the furnace itself:

This lack of v-shaped filters is apparently normal, as it is described on the furnace cover sticker, which says: "Horizontal furnace: Filters are located external of furnace. Consult installer for location."

Interestingly, since most of the vents were closed, I might assume the furnace had shut off due to lack of air, but I can't find what the sticker also says is the "RESET" button: "Auxiliary limit control may be located on blower housing or top of furnace. To RESET, push button on control firmly. Refer to USERS MANUAL for more information. Call qualified serviceman if failure continues."

Also, the sticker talks about a "fusible link", which I also haven't found yet:

Just in case, I hit all the reset buttons I could find, starting with the two manual limit switches:

When I press the brown button on the manual limit switch, nothing happens (I had expected a spring-loaded type of interaction):

I pressed the brown button on the blocked vent tube switch:

There were no buttons on the flame sensor and hot surface igniter, so, I merely wiggled the wires to ensure they were on snugly:

I suspect this is the backside of the fusible link, which likewise, I wiggled the wires to ensure they were on tightly:

I also flipped the on-off switch, on the gas valve itself, a few times:

I also wiggled all the wires and connections on the control board:

I'll run another series of tests, and see if any of that made a difference.

makolber wrote, on Mon, 22 Dec 2014 10:24:18 -0800:

Hi Mark, I had read your suggestion and followed it as much as possible.

There is a flame sensor, and a hot igniter, which are located here:

I don't know yet how to physically 'test' them, but they do not appear to be damaged. There is absolutely no water, and the ground appears good but I need to run more tests on ground to be doubly sure.

The good news is that, after wiggling everything and opening all the vents, and replacing the batteries, I called for heat just now:

First the first time all winter, the igniter lit after the blower motor ran for a minute or so!

Then, for the first time, the flame and igniter went on:

Then, just the flame went on, for about 10 seconds or so:

This happened three times, in quick succession, and then the furnace went back to the blinking.

I will post the blinking video separately, as it seems to be blinking a different code now.

Now that all that went on, it might be time to check the air flow switch. It will be something after the blower mounted on the air chamber. It is a switch that will probably show open and when you have air flow it will close. If it does show open, and never closes when the blower starts up, you have low air flow. Either the blower is not turning or the switch could be bad. If it shows open, hook the two wires together and see if the furnace stays running. Or place your meter across the wires and see if they stay closed. You can probably go to ground from one of the contacts and one side will always have voltage and the other one will not. Get on the one without the voltage and see if it ever gets the voltage.

Stormin Mormon wrote, on Mon, 22 Dec 2014 11:26:40 -0500:

Partial success!

After all the fiddling, I'm finally getting the thermal igniter to ignite, and the flames go on three times, and then shut off, so, that's a partial success, I guess.

First, the LED was solid red for a minute or so:

But then, it quickly switched to what appeared to be a code #12:

Then, the flames went on three times and then off within seconds with a resulting LED blinking code of what appears to be #34:

Given all those inconsistencies within the span of 15 minutes, I'm not sure if things are changing or if there are more than one problem or if the thing just needs to settle down, because those blink codes are changing depending on what is happening with the blower.

The gas valve is definitely turned on, and there is plenty of gas on the stove and in the 500 gallon propane tank.

I will doublecheck that the metal case is grounded, and, I will sand or steel wool the flame sensor and check the amperage if my Fluke 75 can get down that low.

14: Ignition Lockout: Control will auto-reset after three hours. Refer to #34.

It's not an air handler blower issue. He gets the flashing trouble indication as soon as power is applied, without any call for heat, without the furnace firing, without the blower ever starting.

He was getting that flashing , but he just said the heater tried to start after he did all the resetting and checking later on.

The heater could have came on at the very start and failed. This could have tripped a safety device and he finally reset it, only to have it fault again on the restart attempt.

Again, "tried to start", is not an air handler blower problem. If the blower failed, there were clogged filters, etc, the furnace would fire up. run for several minutes, then shut off with a failure code.

Two problems with that:

2 - If it fired at the very start and failed, it's also not a blower problem. The blower typically comes on about 2 mins into the whole startup. For it to reach an over temp and shut down, would require a lot longer.

Hi, First, I'd just clean the flame sensor to get one thing out of the way. I never ran into failed sensor but dirty one which did not work well. Rubbing it with emery cloth always made it work again.