This post is for mom.. She had a brand new carrier forced air gas furnace installed in October in Central NY area. It shut down 2 days ago in the bitter cold weather. A call to the installer brought out someone who didnt really know much. Diagnoses was condensation shut it down. I dont want this thing to shut down on her again and I dont think it should shut down being 3 month old system. Installer did something quick and simple and said "Call us if you have any more issues". I think this is wrong on many levels. Who wants to wake up half frozen at 2AM and wait for a repairman to (maybe) come, when you have brand new system??

I dont know anything about the system but I am fairly handy. Specific questions are 1) Can condensation in fact cause the unit to shutdown? 2) Is it likely to happen again? 3) What is the fix? I need to gather as much info as I can to discuss the situation with the installer so this is no longer possible. Thanks thanks thanks...

Details:
Carrier model 59MN7A120Z241222
Serial - 3013A47078
1 Zone
TStat - Honeywell Pro TH3000 series

If other info is needed let me know and I will do my best to get it.

 

Maybe I am misreading your post but it sounds like you are asking for absolute guarantees of perfection. Nothing made by humans is perfect, we just do the best we can and then fix the mistakes.

How do you know what the service tech may or may not have known?

Very possible.
Would you have preferred he/she spend several hours and then tell you NOT to call if you have any further trouble?
Yes, condensation accumulating in the wrong place most definitely can either shut down the furnace or keep it from operating. Will it happen again? I don't know because I wasn't there and I don't know what was done to alleviate the problem. The fix might have been as simple as re-routing a condensate drain line that had been kinked during assembly or installation, a drain that was too long creating a trap or any of probably a dozen different causes. It may happen again and it may not. I suspect that IF there is another failure it will be from a different cause.

 

How do you know what the service tech may or may not have known?

He was on his cell phone calling boss or coworker telling them he had no idea what was wrong and can he get some advice..... Its not clear if he actually did anything or the system started working on its own again. It actually went down once and came back up byitself for a while, then went down again. This was short time before the final shutdown.

Would you have preferred he/she spend several hours and then tell you NOT to call if you have any further trouble?

I would have preferred someone coming in, saying Ah yes I found the issue and corrected it. You are all set. Instead, my 70 year old mother, who is primary care giver to my father who is wheelchair bound, needs to worry that the brand new heating system may crap out on them again. Do I expect perfection? No.. however a fix with a gurantee that the issue was resolved would be appropriate. Spending time to make sure there were no additional issues would be appropriate in this situation as well. Somewhat of a human factor involved here that I think was/is missing.

One more item I recalled now is the tech said he heard water gurgling around. Does that help to narrow from many possibilities to a few?

 

The gurgling is certainly condensate. Causes are many. Some are the installers fault, some the manufacturer's, some Mother Nature's. What caused your mom's, we don't know because we weren't there but to have a servicer say "you're all fixed up" is really sticking his neck out. I'd much rather hear something to the effect of "I found ..., took care of it & don't think you'll have any more trouble, but if you do, don't hesitate to call".

Those few days when it was very cold had every heater service person running like a mad man. In order to get as many customers back up & running as possible service companies had to use all of their people, even the greenhorns who would usually be with a seasoned tech were thrown to the wolves. "Go & see what you can do. If you get in a jam, call me" I've heard it. I've said it.

 

My moms furnace went down again sadly. A bit of information follows below. I am hoping someone can give me a clue as to things I should or can ask the repairman, or look for. I realize there are limitations on what someone can do or say over internet but any scrap of knowledge I can pick up should help at least some. Also to installers credit, someone came out and looked at it.

FYI - The weather was normal for this time of year, and not overly cold like several weeks ago.

..."Pressure switch shut off and furnace went into "hard lockout" meaning it shut down altogether for three hours. It got too hot." Also there were some error codes, which I am not privy to. I can work on trying to get these but it may be a challenge. Not sure.

Is it possible to make any type of educated guess as to what may cause this? Or anything I can try and provide to someone to help narrow possibilities?

Thanks for any info and helping. I just really dont like the image of my parents waking up the middle of the night freezing trying to get a repairman in there. Luckily this was not very early morning, this time.

thanks thanks thanks..

 

If the pressure switch is a continuing problem, the most common cause for such is improper vent installation. Here are a few things to check:

1: Make sure any horizontal vent runs are sloped up, away from the furnace & there are no dips or bellies in it. Prefered slope is 1/4" rise/foot of run with an absolute minimum of 1/8"/foot.

2: If there are any reducing couplings in the horizontal, they should be of the eccentric (offset) type & the bottoms of the 2 pipe sizes are parallel. Pipe size changes really should be done in the vertical.

3: Judging from the model number, it seems that furnace is 120,000 btu. If that is the case, the vent probably should be 3".

If the vent is too small, that could also lead to overheating problems.

 

Did they actually say "it got too hot" ?

The pressure switch doesn't recognize heat...... just an imbalance in the vent pressure like Grady mentioned.

If the furnace is shutting down on high heat.... that's a different problem.

 

Thanks both of you. Its HIGHLY appreciated. So.. here is a bit more info. The repairman increased the maximum fires blower speed and increased the dropped inducer speed. I really do not know what this means, I am just repeating it. The installer is now somewhat admitting the furnace is too large for the ductwork. I think the information here has helped get this information from them. I am not sure the repairman actually said it got too hot. I will find this out though.

Two questions.

1) If the original issue was condensation, could it be related to the pressure switch or not likely? I am thinking more likely is the pressure switch was the original issue.

2) What to do next.. IF IF in fact the ducting is too small (which sounds like at this point), and the installer installed it like this, it seems to me its an install issue and the installer should fix it?? Is it a fairly easy fix, or it just depends on the installation, amount of space, and other variables not easily described?

Thanks to everyone contributing to this thread. I think its very very helpful and with some luck I think this issue can be resolved.

 

The main air blower speeds are changeable. I'm not aware of a multispeed inducer blower.

If the furnace is oversized then it usually cycles on hi heat as the heat exchanger gets too hot. Increasing the main blower air speed should help that problem. You may feel and hear more air coming from the vents.

If the original problem was condensation then yes.... it can affect the pressure switch.

This is the whole reason for the diagnostic LED(s) on the control board. That code will tell you what the problem is.

 

Would I be able to see the code on the control board? Or better asked, is this something I would be able to get, next time this happens? Or do you need a tool to read the codes? Thanks for your time.

 

Where does the condensate go? To a pump? If so, where does the pump line go? Outside? Is it frozen? I hope he made sure to keep the temperature rise witching range after increasing the blower speed. And inducer fans don't have multiple speeds. One speed and thats it. There may be some condensate trapped inside the inducer.

I'm trying to find literature but I think your model is incorrect. Need to find data on temperature rise and heat exchanger info. By oversizing and not properly setting up that unit, that heat exchanger could deteriorate within years. Anyone know if carrier uses stainless heat exchangers?

 

I beg to differ on the inducer speed point. Some two stage furnaces increase the inducer speed when the burner goes to high fire.

Most of the time the code will be a series of blinks from a light on the control board. Carrier companies are noted for using 2 digit codes for example: blink, blink, blink, short pause, blink, blink, long pause would be a 32 code. You can usually see the code light thru a window in the blower door. Once you get the code, open the blower door & there should be a sticker listing the codes & what causes them.

 

The following link is an excellent manual on the troubleshooting and operation of your furnace. That is a very complicated furnace requiring someone that knows the product well to work on it. The draft inducer blower on this furnace is run at multilpe speeds.


docs hvac partners groups public documents techlit 2F59mn7a-01t.pdf

 

DanNY,
Wrap a chain around it & snatch it out by the roots. Your poor mom probably has the most complex furnace in captivity. That furnace is so unforgiving it will cause the best of techs to pull their hair out.

 

Grady,

That's good to know. I haven't come across any two speed inducer motors yet. I've been getting more into hot air and AC the past couple years and definitely have much more to learn and see. That's actually great they do that, I know most 2 stage furnaces only run a single speed inducer which actually ends up hurting efficiency in low fire due to the tremendous amount of excess air during combustion. Is carrier pretty much the only ones that have this type of inducer?

 

Jeez, all I did was glance at that manual and I was rolling my eyes. Even with that thing by your side, that unit would be a stickler to work on.

 

I'm not sure without going thru the manual again but I think this particular piece of equipment actually has a variable speed inducer. The furnace in question can modulate it's input from 51(?)% to 100%.

 

It's all fine and dandy WHEN it works. I can't stand carrier, they try to put 10 pounds of "stuff" in a 5 pound bag. The more bells and whistles, the more that can potentially go wrong.

 

Not only "can" it go wrong, it WILL go wrong.
The company for which I work installed a couple of these things in a new building & the electrician wired one of them wrong feeding it 240 volts instead of the 120 it should have had. Mr. electrician had a huge bill in repair parts alone. Just the fan motor was close to, if not a little over, $1000. He wiped out everything electronic.

 

..... just what I was thinking. You're right about the variable inducer speed too.

 

Not good at all. Obviously the chain and roots method would be preferred, but not realistic. Its there and I doubt anyone is going to cover cost of removing and replacing with something else. Thanks for the link.. I think. Its been behaving lately but next time Ill try and get the blinky codes and see if I come up with something. Its tricky though as I am not there.

Can anyone recommend another model of Carrier that is somewhat smaller and much less complicated? I seriously doubt anyone will remove this thing but if so I would like to have a ready answer as to what to put in there.