Choosing between HVAC quotes
April 1, 2016 5:38 PM   Subscribe

We're looking to have our home HVAC system replaced, and have received many quotes. However, we're having a hard time selecting the winner. Details below.

We started out with three quotes, all from companies with sterling reputations on Angie's List (which has served us very well in the past). All the representatives seemed thorough and reasonable. None of the resulting quotes agreed on all of the critical points, though. So I thought I'd get a few more to see if I could come to some consensus on the right approach. That just made it worse. We're now up to 6 quotes, including a couple neighbor recommendations on top of the Angie's List companies and one recommended on a local Facebook group.

The quotes are so variable in price that the top quote is more than double the bottom quote. The various quotes disagree on points such as:
  1. Sizing of the air conditioning unit
  2. Sizing and placement of the return air ducts
  3. Necessity (or not) of upsizing the electrical circuit
  4. Necessity (or not) of upsizing the refrigerant line set
  5. Adequacy of existing ducting
  6. Which brand "we never have trouble with" vs. "needs service all the time"
When I have questioned them on these points, each claims that the others don't know what they're talking about. Given that I'm not an expert on any of this stuff, and all of these companies have come highly recommended, I have no idea how to figure out who is right. After 6 quotes, I can't imagine that getting more is going to add any clarity.

Have any of you been through this, or are you in the business, and able to give me some advice here?
posted by primethyme to Home & Garden (9 answers total) 2 users marked this as a favorite
Is your current A/C sufficient? If it is cooling your home effectively (or was in the past before whatever prompted the upgrade), then you can assume that a replacement should be the same size or smaller (depending on the age of your current unit, it may be much less efficient than the new model, so you would not need one as large). Same goes for the line set and circuit. If they worked before, there is no reason to increase capacity.

Ducting is a little tougher, can you provide some more details?

Brands are probably not going to be helpful - there are many, some made by the same manufacturers, and everyone has the one they tend to use.

I would look at the proposed units pretty carefully for their efficiency because that can make a big difference to your operating costs.
posted by ssg at 5:56 PM on April 1, 2016 [1 favorite]

I got a new HVAC system a couple years ago. My neighbor got one last year. His is better and I'm jealous.

Things to look for that are probably worth extra money:

* Variable speed blower (air handler). This is the unit that pushes air around your house. Variable ones can run slowly when they need to, which is quiet.

* Variable speed compressor. This is the unit outside your house that does the actual cooling/heating work. The variable speed ones are quieter AND have a serious advantage for cooling: they can run more slowly to match the load, which is very important for humidity removal. (Many installers like to over-size the system for various reasons, but over-sized systems are actually worse at humidity control).

We also got a WiFi enabled thermostat and although I'm not a fan of Internet of Things, this IOT device is handy.
posted by soylent00FF00 at 6:10 PM on April 1, 2016 [1 favorite]

Response by poster: Sorry, I should have provided this detail.

The existing system is definitely not cooling adequately. The one thing everyone can agree on is that it's drastically undersized for the space it's cooling. They don't agree on how much it needs to be increased.

Regarding the ducting, all agree that the ducts in the attic need to be replaced. Some also say that the return ducts need to be upsized. Some say that the return ducts need to be MOVED and upsized. Some say that they are fine.
posted by primethyme at 6:11 PM on April 1, 2016

We'd need to know a lot more to give you an adequate answer. How large is your house, one story or two? When was it built? Are you just replacing a condenser or the whole system. New systems use a different refrigerant than your old system so the line may or may not need to be replaced. What size do you have now? What are the quotes recommending? There are so many variables that it's really hard to give a concise answer.

In general, you don't want to oversize because if the air conditioner doesn't run enough it won't control humidity like it should and that can lead to other problems. Too small and it runs all the time. Here's a good primer.
posted by Grumpy old geek at 6:38 PM on April 1, 2016

Was any of the quotes based on a actual cooling load calculation? There are methods to calculate the size of the unit needed and I'd be more inclined to go with a contractor who did the math than one who just estimated.

Where are the return ducts now? Where do they propose to move them to?
posted by ssg at 6:46 PM on April 1, 2016

Best answer: We're not really equipped to give you a technical answer to your question here. Few of us are HVAC technicians and none of us have inspected your compressor or crawled around in your attic. There's no way any of us are going to be able to give you a better opinion on what needs to be done than the reps who visited your house, and obviously even they don't agree.

Here's my advice: start by narrowing the field. You don't have enough information to decide based on the merits of their proposals, so use your intuition and pick the two companies that seemed the most reasonable and well-informed to you. Discard anybody who gave you even a tiny qualm or weird vibe. Discard the lowest bid and the highest bid. Pick two people from the middle of the pack who seemed confident, relaxed, and who gave detailed answers to your questions. Be frivolous in your criteria if you must, but just pick two.

Then call them each back and ask them to prepare new estimates. Ask them to outline what they think the absolute minimum amount of work is that would need to be done for the new system to condition your house adequately, and to give you a price for that. Ask them also to offer you whatever upgrades they think would be good value for your house, again with prices. Explain that you need to be careful about managing your budget for this project (they will get that, they have their own budget for your project that they're going to have to be careful about as well) and that while you're not averse to doing more than the minimum, you want to understand what you're paying for. That's perfectly fair, and if they're a good company they won't have a problem doing this for you. If one of them gives you any crap about this, dump that one.

Quiz them on both the baseline estimate and the upgrades. Why do they see this as the minimum amount of necessary work? How did they arrive at those specs for your compressor and air handler? Why do/don't they think the ducting/lines need to be redone? What would be the point of having a new cold air return put in here, or an extra zone there, or a fancier compressor/blower than they specced in their baseline proposal? What about options X, Y, and Z which you had been considering but which they didn't suggest—why don't they think those would be worth it?

You may find that the two companies are more in agreement now about the general level of work that must/should be done on your system, but that one was offering you a more deluxe version at the very beginning whereas the other was trying to give you the cheapest solution that they thought was reasonable. That dichotomy represents two types of sales tactics: one where they try to get you to commit to a more expensive (but not crazy) project up front, and another where they try to get in the lowest bid they reasonably can and then see if they can interest you in some higher-margin upgrades as the project goes along. Which strategy they used depends on their read of you (how much can you afford, are you going to be tightfisted or free-spending about change orders) and also on their personal and corporate preferences for sales, design, and project management. Both strategies are legitimate (their goal is to make you a happy customer while also turning a healthy profit with a minimum of fuss) but they can result in fairly different initial quotes.

Once you have two comparable plans, with well-explained options, and you've discussed those plans with both companies and feel you understand how they arrived at them, you will be in a much better position to make a final decision. You will probably have dealt with more than one person at each company by this point and have had more dealings with them in general, so you'll have a better sense of how you feel about working with them. You'll also finally be able to compare their quotes from a technical perspective! You'll know enough to be able to decide what work you want done (no matter who you go with) and you'll know how much it would cost to have it done by each of the two companies. (There will probably still be differences, but they'll be substantially similar overall.) Then, assuming you still don't feel strongly about one company versus the other in terms of politeness, professionalism, or expertise, just pick the one that has the lower bid.

It's impossible to ever know for sure whether you're making the best choice, but that's just life. At some point you'll have to pick, and if you proceed as outlined above you'll be in a very strong position to select a good company who will do a good job at a good price.
posted by Anticipation Of A New Lover's Arrival, The at 7:24 PM on April 1, 2016 [6 favorites]

Best answer: Our AC went out a few years ago and had a similar experience. One company said our compressor was shot but the handler was fine, another said the opposite. A third said both could be fixed, but not really worth the effort on an older system that could break again. Our system then was middle of the road when it was new, but no one could tell the age of it and all agreed that it was no where near the efficiency or the capacity it had when it was new. Like others have said, we would need to know the size and layout of your home, your climate, and what they are recommending to provide any specific pointers.

Some things I learned then and others to consider:

You say your system not cooling adequately, but did it ever work adequately? What did they calculate the cooling capacity you would require and what is the old system capacity?

ACs have two basic functions, changing the temperature and dehumidifying. If you get a system that is too big, it does not run long enough to "dry the air" so you end up with cool humid air. We had problems with humidity with our old system, so we got one of the two stage systems mentioned above. It has a 5-ton and a 2-ton compressor outside. The 2-ton kicks in when the weather is milder, such as now. Our house is much more comfortable now at 76 degrees than it used to be before at 72 and we don't have issues with the walls swelling up anymore.

The system we bought was one of the most efficient on the market at the time, but it was pretty expensive. The dealer we ended up going with did not recommend this system as he reasoned it would take 5-7 years of energy savings to make up the cost difference at current electric rates, and we would only then be seeing slight savings for 3-5 years. That was one of the reasons we went with him as he seemed pretty honest and practical about it. However, we went with that system as it seemed like it would solve the humidity problem, and it should save us money in the long run.

My neighbor and I both have similar houses in size and layout. I have one 5 ton unit in the middle, and he has a 3 and a 2 on opposite ends. The 2 system setup is probably a more practical and if I had had to replace the ducts that may have made more sense.

Apparently, one of the companies in my regional actually owns the distributorship rights to most of the major brands for several states around and basically sets the price for the systems. That means you may have to pay 2-3 times more for x-brand than you would for the same system if you bought from another region. The smaller companies have to buy those brands from them, so they may not make a lot of money on them even though they are charging higher prices that the national cost. However, there are other brands that may not have the cache of the bigger brands and may be slightly less reliable, but cost more in line with what an AC should cost. If this is the case in your area, this may influence the different companies opinions on reliability as they might be comparing best bang for the buck rather than overall reliability. A few of the companies we got quotes from would specify brands they would not install. Others would have preferred brands, but would install one of the cheaper systems. One told us that no matter what brand we chose, the hardware would basically be cost plus, but their installation would vary based on history of difficulty with not only the brand, but the distributor as well.

The dealer we ended up going with recommended we would be better off spending money on a heat pump than a higher efficiency unit. Even in the deep south with only a few months of cooler weather, he said it would have a better payback than the more efficient cooling. We had different reasoning for the more efficient unit, but had it been a planned purchase, we probably would have tried to get a heat pump, too.

For the electric, there is really no telling without knowing the specifics, but it would make sense that if they were increasing the size of the system it may need more current than the original wiring and breakers were designed for. That may even have been the reason they had an undersized unit there to begin with, as they didn't want to upgrade the wiring to put a bigger unit in.
posted by Yorrick at 9:05 PM on April 1, 2016

I'll throw in my usual thought on this.

Have you looked into all of the rebates you might be entitled to through the Federal, State, Local governments, as well as your electric company?

Have any of your proposed contractors discussed these options with you? Which ones are offering equipment and solutions that give you the best value given your opportunities to take advantage of these rebates?
posted by Ruthless Bunny at 3:58 AM on April 2, 2016

I'm in the process of replacing my HVAC now. My experience is you have to be an informed buyer and not rely on the vendor. Also, I find Angie's List is a useless these days as they've been gamed by the vendors.

1. Sizing of the air conditioning unit
No vendors wanted to do a Manual J load calculation. Do your own.

2. Sizing and placement of the return air ducts
I've read 150 square inches of return per ton. The more returns the better. Do your own Manual D calculation.

3. Necessity (or not) of upsizing the electrical circuit
You don't say if your all electric or gas. My all eletric split heat pump system is on a 100 amp circuit. 60 amps to the air handler with electric heat strips and 30 amps to the outside compressor.

4. Necessity (or not) of upsizing the refrigerant line set
Always get a new line set. The specs for the line set are defined by the system being installed.

5. Adequacy of existing ducting
Again, you can calculate if existing duct work is adequate in volume. Whether it is in poor shape or not is another question. All my duct work is in conditioned space so wasn't a critical issue.

6. Which brand "we never have trouble with" vs. "needs service all the time"
Carrier, Lennox, American Standard, Trane, Amana, etc are some of the major brands. The warranties are all similiar.

I've found this forums very useful. They have some HVAC pros that will answer questions.
posted by LoveHam at 12:31 PM on April 2, 2016 [1 favorite]

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