Unfortunately (and meaning no disrespect) if you have to ask, you're probably not going to be able to recognize a good installation from a bad one. Not all installation problems are visible/obvious. And you can't necessarily assume an expensive install is going to be better than an inexpensive install. Such is the HVAC business, sadly.

You could have the prettiest looking install (regardless of brand chosen) and it doesn't cool right.

Cool right? what does that mean... in the heat of the day the unit doesn't keep up. Erratic behavior in some cases due to changing OAT / how the unit is being operated.

The reason it doesn't cool right? typically this kind of problem can't be diagnosed or guessed from a forum board. This is how roles reverse many times. An installer simply doesn't have the repair experience. The repair market is much bigger than the "let's buy a new HVAC unit"... how many of the "Let's buy a new HVAC unit" people become a "I need a HVAC repair expert"?... by my watch (clock) it's typically any time after about 2 years. I'm sure some markets are different than mine, probably not that much different.

Service: How old is the machine in question? Meaning was it a installation related problem. (you don't decide and in many cases there at least 50 shades of grey matter.) So trust plays a role here as well.

The business that installed it is in the business of selling something. Anything of a technical nature requires knowledgeable people that work for said business, other wise they are probably just going to sell you again. With the newly discovered R410a phase out coming in a few more years... it will be interesting going forward from here. For me and my HVAC company anyway.

I can see it even before it gets here.

There is much more to the HVAC business than what meets the eye. Sure what you can see is important, but not as much what you can't see. What you can't see determines whether it works or not.... the rest is mostly gimmicks. (tricks)

I service the Katy, Texas area.

Where I live, north eastern NJ, I have no faith in vendors in any industry at this point. Too much work, not enough vendors. No need to worry about doing a good job or keeping up with changing standards. There will still be plenty of people looking to hire someone. Usually too much work so the incentive is too work fast because people are waiting and more money to be made.

I haven't chosen the equipment or an installer yet for my HVAC redesign. So a full replacement will be in the works. I'll be doing the ductwork myself. I am selecting the equipment myself based on the heat load calc and other research I can find on best equipment that meets Schedule S criteria. This way no one is "selling" me on what is convenient for them. I'll find the right equipment and use the manufacturers website to try to identify factory trained, or in the least approved installers and research them from there. I've seen factory trained vendors do stuff wrong so everyone is suspect in my book. Living here has made me jaded.

So back to my original question. Even if I can't always see what is in a bad install, I'd still like to have an idea of what constitutes an install that is bad or not optimally efficient. I see this mentioned in every article but not a single one says what they mean by it.

The big “gotchas” is a not certified, unlicensed company/individual/handyman performing the job.

sktn77a, no offense taken. I understand your point. I am pretty resourceful though. Even if I can't see or determine everything, I'd still like to know what the issues usually are. The more I know, the better the questions I can ask. The better I can spot an issue before, during, or after installation. "All knowledge is power", even if I can't act on it.

Plus, might not be a bad exercise so those installers that read this post who do the mistakes and shortcuts can maybe learn something themselves.

Jim Mat, I live in a condo so they will have to be certified and insured to 1,000,000. I will get the permits for it although the town is often crap when it comes to inspections. For me the permit is really just to scare off shady vendors and force them to do a good job. Assuming I get lucky and the inspector does his job.

Often, installation manuals are available on the internet.

Jim Mat, yes, but I assume an HVAC pro will know more than what is in the installation manual. The manual might say to connect refrigerant pipe, but a pro would know the proper way to do so and if there is an issue if they are connecting 2 different types of metals, if precharged pipe is a good or bad idea, how to replace the old r22 pipe with R410A pipe (or other refrigerant) and best way to snake it through the walls. etc.

"I assume an HVAC pro will know more than what is in the installation manual"

Sadly, not a good assumption.

Thanx mike_home, those are the kinds of things I am looking for. I can easily show at the time of a quote that list and let them know those are the kinds of things I am looking for. How they respond will be a big part of who I choose.

"PVC intake and exhaust too close to each other". I have seen a pipe for a condensing furnace that contains both the exhaust and intake in a single pipe. Do you think it is a bad idea. Something like this where I guess the exhaust goes out the top while intake is below under the covered part.

https://www.supplyhouse.com/Rheem-SP20245-Concentric-Vent-Kit?gclid=CjwKCAiAr6-ABhAfEiwADO4sfXm2bWAjk5STVqbkP_OtqPb37h-fbtTys5LeKwrB0F3ct3cBm6tKQhoCozYQAvD_BwE

I am also considering going with a 20X20 air filter next to the furnace regardless if the spec is for a smaller one just to promote more airflow and a filter that doesn't get dirty as easily.

Some more factors you want to not have present-

Not pulling a building permit. (Don't want the inspector checking that all tasks done to code)

Not having a 3rd party duct leak test done.

Not balancing supply grills for even air flow through the structure.

To add to Mike's "duct work is too small" comment, original installations, besides being leaky after time passes, are also most typically inadequate and often inadequately insulated. A good HVAC contractor will assess the ducts and, more often than not, recommend remediation tasks to improve system performance. One very common problem is inadequately sized and number of return grills and ducts.

Something I think is a warning sign - if the HVAC contractor has available time and can start on your project soon if the bid is accepted, that says they're not very busy. The best ones are very busy and other than for no heat/no cool calls, aren't able to do projects right away. One that has time available, has time available for a good reason. Find someone else if your work can wait.

The concentric vent can be used if the installation manual allows it. The problem is if you the furnace is in the basement it is difficult to have an exit point from the side of the house to allow adequate height about the anticipated snow line.

I agree good contractors are usually busy. The best time for an HVAC installation in the NY - NJ area are spring and fall when HVAC contractors are not as busy.

Some more info on my part.

I live in a condo so the exhaust would have to go through the roof which will be a little over 30 feet of pipe to go through my second floor and attic space and clearance above the roof. Can't really go out the side, the association won't likely allow the change to the facade and it would end up being near windows. I might be limited to a dual function pipe since the association is very particular on those things. I do know of someone who did install with this kind of pipe in a separately managed section of my condos so there is some precedent

.

I am doing a wrightsoft full redesign myself. Manual J,S,D and have research some concepts of manual T which is not fully covered by the software. Yes, I know it is better to have a pro do it, but I tried that with 2 companies with good credentials and reviews who failed miserably at it. Long story... So I bought the software and am doing it myself.And expect it to be more accurate since I have been able to get into more detail than a pro would.

I will be doing a complete replacement of ductwork myself. So I know it will be well sealed and well insulated. The only duct work the installers should do is the supply and return connections directly with the furnace. I'd do that too but it might need to be done right away if heating or cooling is needed at the time of installation.

I want to do the install in the spring but there is a ton of work I am not sure I will be able to get done before that.

I will have permits done for the install to keep the company more honest. Don't trust inspectors to do much from past experience which is why I made this post so I have more knowledge and control of the project.

my supply and retrn lines are below grade. For 2 years I tried everything to remove

water from the crawlspace, I never wold of thought ground water was coming in through

there. Problem is, how to fix....pore concrete??? stacking up dirt isnt working.