|Posted on Sunday, December 06, 2015 - 08:04 am: ||
no change. I checked the interior unit. I was going to post a photo, but my GDMF iPhone won't let me...
There are a series of LEDs on the control board upstairs.
D7, red, steady on
d9, red, off
d10, green, off
d13, green, off
d12, green, steady on
d11, green, steady on
and...d4, also tagged "CFM". lit dim, then goes out, then flashes 12 times, then goes out. repeats.
There are also three jumpers. the first I can't read the label, choices are norm, (+), (-), and test (it's on norm). Second, heat - choices A, B, C, D, it's on C. Third, cool, it is also on C. Dehumidify is NOT cut (says cut to enable; I do not have a dehumidifier).
And as I typed this, I reset both breakers and the system has fired back up again.
|Posted on Sunday, December 06, 2015 - 08:46 am: ||
OK, it appears the flashing LED labeled CFM is simply an indicator - the system is set for 1200 CFM airflow. Flashes once per 100 CFM.
The jumper I can't read is "Adjust", it is apparently what adjusts the airflow (+10%, -12%, or test at 70%).
|Posted on Sunday, December 06, 2015 - 08:12 pm: ||
The outdoor unit did not reset because you didn't shut down the power to the air handler. The controls are powered by a transformer in the air handler. The board outdoors "latches" on a system fault, and cannot reset unless you shut down the 24 volt power supply that comes from the air handler. More simply put, the air handler breaker has to be shut off to reset the outdoor unit.
But there is progress. We know what tripped. Some things that could contribute are: The airflow setting is on the low side at less than 400 CFM per ton. I would like to see 1,400 CFM, in spite of the fact that the manufacturer says as low as 300 CFM per ton (my 32 years field experience has been to the contrary, and I will avoid the technicalities on this forum).
The air filter: Filtrete does not even offer air flow rate/pressure drop specifications. Your single 20 x 25 x 1 air filter is on the bottom end of acceptable as far as available cross section. The existing filter size is barely large enough using a standard spun fiberglass throw away filter. The engineering standards assume that type of filter when sizing return grills. It sucks in the modern era. Modern air handlers' fan sections are not up to the task if you have any air restriction issues.
The true and proper way to assess the issue is to perform a static pressure test and make what ever changes are needed to get the airflow up to speed.
Now that I have rambled around, I know you can't check he duct static pressure, but you CAN do this: Using an accurate thermometer, check the temperature of the air entering and leaving the air handler with the aux heater disabled. Give it 10-15 minutes to even out. You need the thermometer IN the air flow. If you can't stick it thru the ductwork, put it on a stick and stick it in the grill so you know you are measuring the actual air temp. 18 degrees or so difference between entering and leaving air is normal. 25+ and you are in problem territory.
The other thing, is to remove the air filter and run it without one for testing
purposes. Try it with and without the filter while checking the entering and leaving air temperatures.
My first bet: a lot of little issues in the air side add up to a problem. Second bet is the unit is overcharged. This is one of the worst issues in the field today. Nobody wants to take the time to properly test and adjust the refrigerant charge. If you see someone "testing the charge" on a system using only a set of pressure test gauges, they have no clue what is going on, they are perpetuating the "proper pressure" myth.
Do this, if nothing else: Switch to the cheapest, thinnest, whispiest fiberglass filter you can find. See if that stops the tripping.
Serious advice: You system has a problem that will eventually kill it. You need a professional company to evaluate it. Many studies have been done on system design and implementation. My experience has been that around 80% of all residential HVAC system suffer from insufficient air flow caused by incompetent engineering, design, or installation. Your system has a variable speed blower motor. If the return is choked up, it will kill the motor. Not TOO bad while it is still under parts warranty, by over 1k if the warranty is invalid. Contact the dealer that installed the new system and make sure they registered the warranty. If they did not, the warranty is only 5 years by default.
|Posted on Sunday, December 06, 2015 - 09:02 pm: ||
Excellent advice, thank you!
I will procure some thermometers to test airflow temps. Everything in the attic is accessible - any particular distance from the air handler? Or just "find a spot I can get to"?
I will also have the pros check it out. The TX/V was replaced by a contractor...but they were not Armstrong dealers. There are two in the area; I'll have one of them come check it out.
Any guess why it will work fine for A WEEK when I have it locked on a temp, but the first 24 hours I have variable programming, it trips the fault?? THAT one has me stumped...
Here's a question re: pressure drop. I have a Cummins diesel truck. It has a vacuum gauge on the airbox. Could I stick that in the intake duct for a reading? Maybe? Or does it not work that way?
I also, while I had all the covers off today, mapped every single wire in the control circuit. I can post or email it if you think it would help any...it *looks* right to me, but I'm just a schmuck who's not afraid to take stuff apart
|Posted on Monday, December 07, 2015 - 05:46 am: ||
Good thinking, but the gauge from the truck won't work. You need one that can read from 1" negative water column to 1" positive water column in increments no larger than .10.
Your system's target external pressure is .5 inches water column or less total. It will work ok up to about .7 or .8 as long as the return side is below .2, it will just be noisy from the supply grills. Think of it this way: stick a straw in water and suck on it just hard enough to draw the water up 1/2 inch.
The air flow demon almost always lives in the return. The kind of blower in you unit does pretty good at blowing, but sucks at sucking. Restrictions cause cavitation. cavitation equals poor airflow, Cavitation is also what kills variable speed blower motors. When you set the controls for the motor to run at a particular CFM quantity, the motor is set to run at a specific RPM (the algorithm assumes you are operating within acceptable static pressures). Cavitation causes the motor to over speed, the feedback to the controller then makes it slow down. When it slows down, the cavitation stops, the wheel "bites" and slows down more, the controller then speeds the motor back up. The endless loop overheats the ECM and it dies.
When checking the air temperature split, anywhere in the return side is fine, on the supply side get 2 or three feet down stream so the air is mixed properly.
|Posted on Monday, December 07, 2015 - 08:09 am: ||
Also, my return is literally six feet long, with a single large-radius 90 degree bend. Ceiling, up, turn, horizontal for about 4 feet, into the unit.
I changed to a milder program last night - 67 sleep, 68 wake. Insomnia got me up at 0500 (still in the 67 timeframe) and it was blowing low-speed, warm air, working like it should. Come wake-up time and 68 setting...tripped again, same code (green light).
Does the system try to increase freon flow when there'a a big temp change called for? I thought freon was a constant-rate flow, but I guess I could be wrong, and if it is variable, I suppose that could explain the "fine on locked temp and trips on program temps"...
|Posted on Monday, December 07, 2015 - 10:46 am: ||
The outdoor unit has a single speed compressor, so the refrigerant flow is constant. However, in a heat pump system, the indoor coil has considerably less volume than the outdoor coil. An overcharged system will run in cool mode and trip in heat mode.
The "trip in programmable offset mode" could be explained by the differing indoor and outdoor conditions causing a pressure spike.
Here is a "no tools" check. With the unit running in heat mode, go to the outdoor unit. There are two copper lines that go into the house. DO NOT touch the larger, insulated line, it will be hot enough for an instant 2nd or 3rd degree burn (it is the "hot gas line"...feel the temperature of the small uninsulated line that is the "liquid line"...it should be decidedly warm...if it is too hot to hold on to, that indicates an airflow issue....if it is not warm at all, it is overcharged. Not exactly scientific, but it can point you in a direction.
|Posted on Monday, December 07, 2015 - 03:44 pm: ||
Contractor who replaced the valve is coming tomorrow to check pressures. We shall see.
|Posted on Tuesday, December 08, 2015 - 09:32 am: ||
Well, they sent "the crusty old guy" this time lol. He hooked the gauges up, and the high side was reading over 500 (psi? in-hg? not sure what units). Ran the unit for a while, kept popping the valve to bleed some freon off...did that for about 25 minutes and said "ok, we overcharged it when we did the valve...no charge for today's visit".
Going to go to an aggressive program today, and see how things behave Ambient right now is 35, supposed to be hi 40s today. Going to pull back to 64 for the day, then 71 when I get home. That was a guarantee-trip before, we'll see how it does.
And for the sake of education, I'm also going to buy a pair of digital meat thermometers, and place one in the return duct and one in the supply, just to monitor the temp delta.
Thank you SO MUCH for all the advice!
|Posted on Tuesday, December 08, 2015 - 07:13 pm: ||
Got home from work and......
It could be that I was loading gear in the truck in 37 degree ambient, but could it be that the warm air coming out of the ducts is even WARMER now that the freon charge is correct?
Ahhhhh....so happy to FINALLY have things working properly. I still need to check return and feed temps, but I was so wiped out after work (and starved), I didn't get thermostats on the way home...but I will.