HVAC experts please help!

[Wayne 962]

I’m under the house right now. Check out this terrible design!

[Wayne 962]

Another

[dad911]

It keeps reading a fault saying "motor out of range" in the high range which means rpm is in excess of 1,300.

Do you have a way to measure rpm and see if it's throwing the code in error?
https://www.pelicanparts.com/cgi-bin/ksearch/pel_search_2016.cgi?command=DWsearch&description=tachometer

[908/930]

Was thinking what dad911 is thinking, feedback from motor control module not working correctly?

Can you just lock it on low heat for now? Noticed there is a switch for emergency heat (SW-4), not sure what sensors that bypasses, looks like it skips the blower calibration and just runs blower full speed.

Are those pics part of the return? Looks like they were trying to get noise levels down and the flow at the same time.

[Wayne 962]

That was my next move - lock it down on low heat if this doesn’t work. Good thinking!

So I just rehooked it up - what a pain getting it around that beam in this tiny crawl space. I kept knocking my respirator off. I’m now standing in front of it watching it run for eight minutes. That is the amount of time they say you should see error codes.

When I ran it in test mode it showed me a 41 error code with the shortened pipe - different than the 44 but certainly not a 11 code. I also knocked loose a bunch of dust and dirt thru this whole process and now that stuff is getting the filter dirty really quickly. So I’ll have to see if the hardware store up here is open tomorrow (not likely).

Eight minutes now running full blast without any errors!

Wayne

[Wayne 962]

Ten+ minutes now with green light on.

Wayne

[Wayne 962]

Darn it. Code 44 again. And now the heater motor is making a different noise. Sounds a little louder or so. Maybe this a motor / controller issue after all.

Wayne

[Wayne 962]

Originally Posted by Wayne 962

Darn it. Code 44 again. And now the heater motor is making a different noise. Sounds a little louder or so. Maybe this a motor / controller issue after all.

Wayne

If it runs fine for 10 minutes and then encounters a problem, then chances are it has nothing to do with the intake, or dust or magic FAU gremlins inside of the ducts. It's probably something to do with the motor or controller I think...

-Wayne

[black73]

Have you tried turning it off and turning back on?

Seriously, cut power at the breaker, give it a few minutes, turn back on. Might need a reset. Worth a try.

[cabmandone]

Originally Posted by Wayne 962

cabmando - I'll get you that info soon, heater is apart and it's getting cold so I need to work semi-quickly.

So, I disconnected the return line - what a convoluted POS setup this is. BUT - disconnecting the line did not make a difference! I ran the heater with the return line disconnected, *and* with the filter removed (just for 20 seconds during the test mode), and it still came back with the 44 code. By the way, it shut down last night for it's "3 hour reset cycle" on its own.

So, with the return disconnected and the filter out - it still gives me the 44 error! Running the motor with the cover open (so it gets air from the room instead of from the return circuit) resulted in no errors. So, is there an obstruction in the return duct all of a sudden? Is the line just so long it can't get air? I thought for sure removing it from the screwed up intake vent (semi-crushed by the beam ) would help, but it did not! Right now, I'm headed back down there, and I think I'm going to chop about 20' off of the return line and see what happens. I have to be careful not to screw up the entire setup. We do have another FAU in the house, and we do have a wood burning stove, but I wouldn't hear the end of it if the unit was down and inoperable for several days...

-Wayne

Seems to me if it'll run with the blower door open bypassing the return duct, your issue is the return duct and most likely since it faulted with the flex unhooked from the drop duct coming out of the crawl space, your issue is the drop duct itself. Need to know the size of that duct.

Originally Posted by Wayne 962

If it runs fine for 10 minutes and then encounters a problem, then chances are it has nothing to do with the intake, or dust or magic FAU gremlins inside of the ducts. It's probably something to do with the motor or controller I think...

-Wayne

I'm not saying it's not an ECM issue but again, if it will cycle properly with the blower door off, it seems to me the issue is in the duct. If this was a new issue I'd say Yep! It's the ECM. But seeing how this code dates back several years based on the writing on the cover, I'd say this thing has had an issue since day 1 and the tech changing the filter was just to say they were doing something to fix the problem. His next move was probably to whack something with a screwdriver.

BTW, there is another member here who is really well versed in this furnace. I don't recall his name but I remember him chiming in on another thread. I'll see if I can find his username. You might be able to PM him for advice.

Update: I found him and sent a PM asking if he could chime in.

[dad911]

Are you sure the squirrel cage is clean? Usually just a few screws and the whole motor/blower assembly slides out.

[cabmandone]

For the 44 code I noticed this in the troubleshooting guide
"You have excessive restriction in air delivery system. Check filter(s) and ductwork. If problem still persists, replace furnace control board. Make sure replacement board has a date code of 9506 or later. This new furnace control board will allow unit to run in high fire when necessary. See description of operation at start of Fault Code 44. If problem still persists, use Appendix E to evaluate."

From Appendix E: "If furnace is on a call for heat or cooling and duct static is too high, ICM tries to overcome external static pressure. If duct static is excessive,
ICM RPM will be out of range and a Fault Code 44 will flash on circuit board"

[Fischer_76_911S]

Phew, what a long thread. My two cents from far away.

1. Lots of good advice on here.
2. Static is a function of both return and supply. Door off reduces static, but that doesn’t mean problem was with return.
3. Advice given earlier to check evaporator coil and clean if needed. Also check if internal insulation around coil or furnace is loose. I had one Job where the insulation blew onto the coil from the side of the cabinet when running, threw a code, and then returned to its normal position at rest.
4. Check insulation around blower motor for same problem. Door on could equal insulation sucking in and blocking 50% airflow.
5. Good advice for locking down in low speed, but see above.
6. Replace motor if all else fails, especially if it is original. I’ve seen over speed situations on ECM motors, though very rare.

My $0.02.

Bob

[fintstone]

Originally Posted by fintstone

You simply do not have enough return capacity to run on high heat. You need another return to increase capacity. Look at Appendix E.

http://www.graycoolingman.com/uploads/1/0/6/6/10667336/58mvp-_2_stage_variable_speed_troubleshoot_guide.pdf

It sure looks to me like the previous owner increased the size of the house and added supply ducts (and probably upsized the furnace) and did not increase supply air to match. If that one return is all you have, it is likely just not enough. You would need to cut a hole in the return plenum and add another return...preferably from a different floor/part of the house (if possible).

I could not really see your return air plenum in the photos (assume you have one). If not, you probably need to add one. If you can access it easily, depending on design (and the area it is located), you might be able to open it fairly easily and allow more air in to test if the additional air would solve your problem.

Also, I would suggest that you update the grill on your existing return to one with larger spaces between the fins. Those with such narrow slots also restrict air flow.

Of course, I assume that by not you have confirmed the ductwork you were examining is not collapsed or blocked.

Good luck.

[908/930]

Probably worth making up an incline manometer and check what is really going on in the ducts.

[Wayne 962]

So, I shortened the duct - I still have the problem, although it seems "less" now. I think that there may be two problems - a poorly designed intake system, *and* a motor that may be getting old. When I shortened the intake, I rant the unit for a while with it disconnected - still gave the error code. Also did it when I removed the filter. Maybe there's a blockage on the pressure side, although it shouldn't work then when I open the blower compartment and bypass the intake.

I wish these machines had better error diagnosis codes...

-Wayne

[cabmandone]

Your duct system is a mess. My guess is that supply and return are sized wrong. This is why the code existed several years ago and why it likely never went away. I'd bet the system never worked properly but on low fire it was simply out of sight out of mind.

[908/930]

Prior to shooting darts at what needs to be replaced, should confirm what static pressure the fan is seeing, page 36 of the manual that fintstone provided. there is a possibility the furnace is working properly and the ducts are undersize. Pick up a 0-3" wc, water incline manometer.

Cabmando did ask this but what size unit is this?

[Wayne 962]

We've left the house. I've got an HVAC guy coming to look at it on Thursday. It's a house in the mountains, so my tools and equipment are not the same that I have here in Los Angeles. I basically have a large carry-around toolbox with some hardware-store Stanley tools. I do have a manometer here at home (used for diagnosing my pool heater problem - that's another story - six visits from the "techs" couldn't fix it - I had to do it myself), but I didn't have that there.

The fact that the heater still gave an error code with the intake disconnected from the convoluted intake duct, leads me to believe that either the motor is getting a bit old, or indeed, perhaps the system wasn't setup property from day one.

[Wayne 962]

Originally Posted by 908/930

Cabmando did ask this but what size unit is this?

Here are the full specs on the heater. It has the propane conversion kit on it, and the house is located at about 8,500 feet above sea level. I wonder if that would make a difference in the calibration of the thing. You'd think it wouldn't, in that it would automatically calibrate for air density?

-Wayne