I don't believe the furnace is the problem and if the tech did nothing more than Wayne said he did, that's some kind of piss poor diagnosis. One look at that installation by a good tech should tell them it's not a professional installation. Installing a new furnace with the existing duct system might result in the new furnace not operating correctly. He could have a 2 stage heat with a basic variable speed fan installed and it might work okay but I'd want that duct system assessed for proper sizing.

I'd be interesting in knowing if that pipe off the front is the only supply trunk. From the look of it, it's either a 12" or a 14" round. I'm leaning towards a 12" because the plenum on the furnace will only be 16" wide and from the video it looks like there's about 2" on either side of the pipe to each side of the plenum. I'm thinking a 12" is only good for about 500 CFM. Even if it's a 14" it's only good for about 600-650 I think. So if that's the only supply he's not moving enough air on the supply side and the return is choked at that crazy box system.

I’m the same as Wayne often being disappointed in services. One just needs to look at the brighter-side of things.

I was in Home Deport where my general rule is to never ask for help (not possible when I’m with my wife). A very young lady approached to help me on some random problem I had. I was polite and described where I was stuck. She was extremely knowledgeable and quickly offer a couple of good solutions. Obviously, that’s a rare situation. I always encourage those “kids” to work hard and get a great education no matter the challenge.

As noted several times earlier in the thread, it is pretty clear there is not enough return (regardless of your fault light...which also seems to indicate the same). You can test this theory relatively easily by opening the supply plenum to allow more air (either at a seam if accessible or a cut to allow a future additional duct). Opening the door of the furnace should have the same effect (but if that was not enough to convince you). If you had integrated AC, you would have noted this long ago as the system would have frozen/iced up.

I thought I read somewhere in this thread that the return air duct was at least 16". If not then the problem lies exactly where you say it is. For a long return air I would go as big as I could. This might involve some custom sheet metal to get around obstacles.

Also one could install 2) 12" ducts with wyes at either end to run smaller ducting through tight places. I once did a calc on a round shape and an oval with the same circumference. I was surprised at the results. Another fact is how much bigger a square is using the same hole.

If the return is inadequate, a quick temperature rise measurement would tell that. Too little return air = higher temperature rise. There's a temp rise range on the furnace label. As Bob pointed out, static pressure is a result of supply and return.

Again. Small town. And this company is the only ones allowed to work on Carrier units. The other guy (supposedly someone better) won't come to look at it because Carrier won't sell him parts because he's not an authorized technician.

Starting to smell the racket?

-Wayne

Yup, quite different once you are away from a large city, I'm still not use to it.

You can troubleshoot it yourself, at least verify if the ducts are undersize, there are youtube vid on how to check ECM motors, Genteq offers aftermarket replacement if needed, should be others available. Condition of the heat exchangers would also be a concern.

The $6k sounded like what I would expect, converted to Canadian price of about $7800, if that was 100kbtu latest and greatest. Part of the reason I chose not to install Carrier is the problem with getting some parts. Two 60Kbtu ended up about $11k installed up here, I did all the ductwork myself, sized correctly, really didn't trust the local support, the gas fitter who installed ended up leaving swarf in the PVC exhaust of one of them that ended up plugging the condensate drain for the draft inducer blower, the water sounded like a bearing failing, so back to repair two weeks after install.

Ask him to go look at it and tell him you'll get the parts. It's not like you need them immediately. If he'll diagnose and let you get the part, I'll hook you up.

I'll make a call today and see if I can get my hands on a blower motor for the unit. You've got a pic of the model/serial number back a few pages.

Or there's the option of skipping the tech, figuring the blower is jacked and replace it yourself.

I sent you a PM but here's the ECM for a better price than I can offer and it's free shipping
https://www.amazon.com/Bryant-Carrier-HK52ER156-CONTROL-MODULE/dp/B00QW2RCJ2

Even better here's a replacement motor that has the right PN. Never used one but you saw what my price was for the OEM and you saw the price the tech quoted you. Worth a shot.

https://www.amazon.com/ClimaTek-Upgraded-Furnace-Carrier-HD52AE156/dp/B087SMGG5Y/ref=sr_1_1?dchild=1&keywords=Carrier+HD52AE156&qid =1610372828&s=industrial&sr=1-1

Did I mention that $300 post fee for diagnostics and consulting? :D

Here, the racket is that only installers approved by the manufacturer can sell their upper end product line. Any licenced tech should be able to purchase parts for any manufacturer.

I don't know of any local carrier supplier that won't sell to a licensed tech. You won't get the same discount as the Carrier dealer but you can still buy the parts. Carrier's exclusivity is based on location. I was a Carrier dealer but a bigger company came in and had a Carrier dealership so I was odd man out. Didn't bother me since Payne is Carrier without the advertising and most of the systems I was installing were entry level single or two stage variable speed stuff in manufactured homes.