It's quite common to just simply quote equipment in the quote and pay no attention to other details of the job.

The system(s) they quoted you are 5 ton, you have 4 ton now. You better make sure "you need" a 5 ton. AC needs to be sized properly, larger than you need is not better can cause serious problems.

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All equipment quoted is high efficiency (regardless of brand name): costs more.

What's included: you mention zoning. --- costs more.

Converting 80% gas to high efficiency gas... costs more, all flue pipe must be converted to PVC pipe. (this can be challenging for some homes) costs more.

What else is included in the job? proprietary controls? duct work? refrigeration line set?

I service the Katy, Texas area.

How large is your house? Is it two stories? What is the size of each zone? Where in the Bay area are you located? What are the hottest summer highs and the winter lows?

I find it hard to believe that a house in the Bay area needs 5 tons of cooling and 120K BTU of heating. Did anyone of these contractors do a load calculation? Most houses don't have duct work large enough to provide the air flow for 5 tons of cooling. Installing over sized equipment is a waste of money and lead to problems.

I realize prices in your area are higher than average and HVAC contractor labor is in short supply. The only way to verify if the prices are fair is to get multiple quotes.

I think the Carrier price is high because he has quoted 24VNA60 5 ton inverter system. I think this is over kill. The 59MN7B 120K furnace is also overkill. When I see things like this I get the feeling equipment in your area is in short on supply so the contractor is going to install whatever the distributor currently has in stock. It works out well for the installer. Higher priced equipment means more profit and no waiting for back orders to arrive.

The Lennox quote is also a 5 ton AC with a 90K BTU furnace. The furnace is reasonable, I still question the 5 tons. The Amana is 5 tons and 100K BTU furnace.

Do the quotes include a thermostat? Is the zone control and line set being replaced? What filter is included? What is the parts and labor warranty?

My advice is to first concentrate getting the proper equipment for your house and then compare the prices. I was under the impression all HVAC replacements in CA required a load calculation. If so I hope none of these contractors fudged the numbers so they can justify this over sized equipment.

@Dave Johnson,

The investment you're planning to make is substantial enough to follow mike_home's advice and ensure the system--to include the ductwork--and the equipment are properly sized. If the contractors you are considering are "replacement-only" service contractors, you will be well served to find one that also does new construction, has the necessary design competency and is aware of current code requirements in your area.

"I was under the impression all HVAC replacements in CA required a load calculation."

Yes, but only if a permit is pulled for the work. For bids I received, when I asked if the bid included the permit fee and costs of compliance (like a duct leak test and prescribed but limited remediation, which is also required to a certain leakage factor but only with accessible ducts and unions), about half would respond with something to the effect of "We don't normally do that but we can if you want. We'll have to increase the price quote, let us know if you want to go that way". And with too many of them, the calcs done and submitted are fudged and useless anyway.

House construction does vary and affect sizing, as does location. To say "Bay Area" encompasses many different microclimate zones with different temperature extremes. I'd like to hear from the OP but with his stated equipment sizes, I'm going to guess the house is in the 2500-3000 sq ft size. I do agree, the equipment may be too large, especially the 120K furnace.

Reflecting on the two system replacements (two different locations) I did about 4 years ago, just one in the Bay Area but the other in another high cost part of the state, the most important factors that I believe led to very successful installations were:

1) Finding HVAC contractors who were ethical, knowledgeable- no-BS people who did their work using today's accepted best practices. Including, carefully done honest load calcs. When getting quotes, it wasn't hard to tell the slimy type from the real ones.

2) Accepting the recommendation of both chosen to do the work to do duct sealing before the testing was done, because joint leaks (one a hard metal system) were everywhere visible and doing so at one house would take nearly a week.

3) Trusting their judgement to significantly downsize equipment to comply with findings of load tests. Doing so significantly increased comfort and temp stability.

4) Keeping 80% furnaces. Both said (independently) that in our mild winter conditions, the gas savings from having higher efficiency furnaces would take a long time to amount to enough money to pay for installation of the different exhaust lines for higher efficiency units.

Thank you all for the detailed responses. Here is some more info.

The house is 3100sqft. Two levels (corresponding to the two zones). Both levels have nearly the same footprint, probably 55/45 split lower/upper if I had to guess. First level has 10ft ceilings. Second level has 9ft ceilings. Roof is cement tiles which I think are good insulators. LOTS of windows (double paned I think, but old).

We are in the East Bay hills near Castro Valley. Average summer highs are in (F) 70s but can be as high as 90s (and that happened quite a few days this year). Average winter lows in 40s.

We have not lived a whole winter in this house yet, but this summer on the hottest days, the current system was not able to keep the entire house at 72, it would start warming up a few degrees above target late in the afternoon. Maybe that is a result of the system being old, or maybe it suggests 4-ton is not enough. We also blew a 15A fuse a couple times FWIW. Of the 3 companies I've had out, the first two after quick glance at the house and system recommended upgrade to 5-ton. The 3rd one at first said he would want 4-ton, but he did do detailed load calcs which took him nearly an hour, and he eventually settled on 5-ton also. The intake filter is 20x36, if that informs the decision at all.

In terms of what else is included in the work, the quotes all describe removal/disposal of all old stuff (obviously), new flue if needed, some new electrical and plumbing components, etc. The contractor I am leaning toward (the Lennox Elite system) specifically mentions permits and HERS testing in the quote. That one (for an extra $3k) also will redo the zoning system and thermostats with Lennox iHarmony/iComfort. Which may also be able to turn our house into 3 zones rather than just 2. I will probably do that, but I didn't include it in my pricing comparison since none of the others suggested redoing the zoning.

My major question here was just in a very rough "ballpark" sense... are these prices in the right area? Or are they crazy? Should I try to negotiate? FWIW, the contractor I am leaning toward (even without considering price) is charging less for a Lennox Elite system than one of the others is asking for a Lennox Merit system. So that seems like a good sign. The contractor I'm leaning toward also does 10yr labor warranty which seems stellar. They're kind of a big brand name around here. Might as well just come out and say it, they are called "Jazz" and seem to have a great reputation everywhere I can check.

Those prices are about twice what I would pay here in central NC. Having said that, houses in SF are four times what you would pay here in central NC! The only way to find out what the going rate is in your area is to get multiple bids.

Be aware that "10 year labor warranty" (and, often, parts warranty) usually requires annual "maintenance" agreements which can add up to more than replacing a system over the 10 year warranty period!

Yeah I imagine labor rates here are at least 2-3x what they are in NC. Not sure how much of the quote accounts for labor vs materials. I imagine even the materials cost more here too (but by a smaller margin than the labor), since the entire supply chain is presumably full of associated local labor costs.

I think 5 tons is too much in your area. If it's 85 degrees outside and 76 degrees inside, expect it to take 3 hours or a bit more to cool the house down. Anything faster than that and you're oversized. Call an insulation contractor and have them look at your attic insulation. Money spent on insulation is better spent, especially for summertime comfort, than money spent for too large AC equipment.

An alternative if it's possible to shift the ductwork would be to have one system for upstairs and a second one for downstairs. THAT would make a big performance difference.

I paid $25K for two new furnaces and HVAC systems and 9 man days of duct sealing but that was 4 years ago. Unless you plan to live in the house 20 years, I think you can get top brand models in their lesser lines (Like Pontiac instead of Cadillac, Bryant in stead of Carrier) and have a very nice system.

I had to wait over 2 months for a very busy Bryant contractor. Supply and demand, business is booming and prices are higher. But I would go downmarket a bit with the equipment to find savings, but stick with the better brands.

Good luck.

Duct sealing is critically important for system performance. If your duct work is leaking conditioned air into your attic or vented crawl space it's not going where it supposed to and you're only getting the benefit of what actually does.

Duct sealing and performance is addressed in current codes, but if my memory serves me correctly, it wasn't until about 10 +/- years ago. And if the installation work was not subject to inspection or performance testing (i.e., done without a permit) you get what you get. If the duct work is leaky, the solution isn't to upside to a 5 ton system, but rather to seal the duct work.

The installed cost is typically twice the equipment cost. Extra labor cost could be added if the installation is more difficult.

The choices you were offered is not what I would call an apple to apple comparison. The Carrier & Lennox choices are the closest of the 3. These two choices are variable or inverter technology. The Amana choice is merely 2 stage unit.

The Carrier choice looks to be top of the Carrier line from what I can find. Lennox top the line in the realm of this particular Carrier unit would be Lennox DLSC series 19.5 SEER Model XC25-060-230 (as the SEER rating of both of these machines would be separate by 0.5 SEER margin difference.... every little bit adds up, especially if you're paying over 20 cents per KWH.)

There isn't much difference, just slight - the Lennox XC25 boasts 1% modulation --- so it has the ability to "load match" the structure better given whatever the load is on the structure in 1% increments up or down. You'll gain 1.5 SEER in efficiency with this change. In that regard it would be impossible to "over size" the air conditioner as it will only deliver what is needed in the inverter or variable compressor realm. If it is over sized, it would just never use that capacity, these machines start low and ramp up as needed. They don't over ramp, they are designed to run all the time at the lowest speeds needed to cool or heat the structure.

To complicate this decision further you could look for a Bosch dealer in your area as Bosch inverter works *like* these two options without the need of a proprietary controller. Retail costs of those can easily be $800 - $1000 or more. Complicating things more later as this system ages is then finding a control that will operate it if the manufacturer decides they no long wish to make or provide the control. The problem right now for Bosch is that equipment is not available anywhere that I know of.

The Carrier Green speed has an emergency mode of operation to go back to legacy control options, but that then turns this maching into a two speed unit. I would think Lennox option might be the same in that regard, but Lennox is quite tight lipped on that so I don't know for sure. (either model mentioned in this thread)

"In that regard it would be impossible to "over size" the air conditioner as it will only deliver what is needed in the inverter or variable compressor realm."

Time out. HVAC systems--including variable refrigerant flow systems--still have turndown limitations. Systems where the compressor motor speed is regulated by an inverter typically control between 40% and 120% of capacity. So while they are more forgiving with respect to improper equipment sizing, they can still be undersized or oversized.

HVAC manufacturers sell their products under multiple brands. Often you'll find the identical product under different brand sold by different dealers at different prices.

• Note that the Carrier 24VNA9 is identical (except for packaging) to the International Comfort Products Ion sold under the various ICP brands with slightly different model numbers (e.g., CVA9, TVA9, HVA9).*
• The Amana SS-ASXC18** differs only slightly from the Goodman GSXC18.

*ICP is a Carrier subsidiary as is Bryant

**Amana is a Goodman brand

There isn't much difference, just slight - the Lennox XC25 boasts 1% modulation --- so it has the ability to "load match" the structure better given whatever the load is on the structure in 1% increments up or down. You'll gain 1.5 SEER in efficiency with this change. In that regard it would be impossible to "over size"

What sort of increment does the lesser model (EL18XCV-060) have? I thought that variable speed was in general a solution to that problem. Though I understand that not all "variable speed" components are created equal. I can find on the XC25 spec page the 1% metric. I can't find an equivalent for the EL18.

Regarding the oversize dilemma, the 20x36 intake seems to be perfectly sized for 5-ton. Also I realize these are very rough estimates, but every calculator I can find online says for my region, anything in the 2600-3100sqft house size is 5-ton candidate. So I am not only in the 5-ton range, I am at the upper end of that range. So even if my exact area is a bit cooler than some neighboring areas, it still seems hard to believe 5-ton would be a significant oversize, again considering the current 4-ton cannot keep up on the hottest days.

What sort of increment does the lesser model (EL18XCV-060) have? I thought that variable speed was in general a solution to that problem. Though I understand that not all "variable speed" components are created equal. I can find on the XC25 spec page the 1% metric. I can't find an equivalent for the EL18.

Unfortunately this model EL18XCV-060 doesn't provide that kind of information. It just says "it's the first of it's kind" --- essentially means it's an older model, the very first is how I read it. In the Inverter realm of AC's start up is rated by Hertz starting at 0. There are many ways in which manufacturer's allow how fast or slow the compressor runs via the Hertz rating.

In the US, power systems run at 60 hertz. -- This is power from the pole, 240v at 60 hertz.

For the Bosch inverter --- the one I am most familiar with -- 240v power comes in converted to DC voltage, then thru a rectifier is converted back to AC voltage with the ability to ramp up or down the hertz rating that will either slow the compressor or ramp it up. This hertz rating is continually ramping up and down --- to come to any conclusion of what 1 hertz difference is in terms of "capacity" --- this would depend on a wide variety of technical information. Just explaining this because it's no where near the 40% realm of what the home builder says.

Typically slowest mode for the Bosch for my configuration starting from 0 ramps up to 17 / 18 / 19 hertz in a 4 ton configuration. It will then stay put for awhile depending on load conditions all decisions are made by the Bosch unit as long as the call signal is active (call for cooling) . In my configuration the compressor speed tops out around 61 hertz if I am not mistaken. So what does 1 hertz increase / decrease mean when it comes to capacity? A marvel of modern ingenuity if you ask me LOL.

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Differences from Bosch to Lennox.

Lennox has proprietary communication controls that communicate with outdoor and indoor units. So they are in that way able to include blower modulation in the algorithm they use, ramping the blower up and down as well as the compressor speed.

Bosch is fine with constant blower speed of at least 350 CFM per ton. I love my Bosch, it's great. However, it was the first version or 1.0 model. There's some differences in Bosch 2.0 model changes to algorithm and a slight bump to efficiency, still ramped via hertz rating so nothing changed in that regard on the Bosch. I chose the Bosch 1.0 because? It was the only model available at the time. Time moves on....

So I believe the Lennox XC25 model was the second model with changes to the algorithm used to control the compressor, fan speed etc to squeeze more efficiency from it. 1% modulation is crazy good if true. I don't have any real reason to believe it's not true. Given how Bosch ramps I don't think it's out of the question.

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Some models from Carrier limited their inverters to merely 5 speeds. This was several years ago and from what I can see the model you list here is not of that variety.

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Square footage is only one consideration when it comes to HVAC sizing and unless you are privy to a heat load calculation done on your home it may have come in at slightly over 4 tons and they just upsize it one more size and there is no such thing as a 4.5 ton residential AC unit.

At 3100 sq. foot and choosing an inverter AC I'd say you're ok with the 5 ton. It's only going to deliver the capacity needed, this is how these machines were designed to operate. Start low and ramp as necessary, making it impossible to worry about sizing problems. Obvioulsy if you're paying for a larger system than what you need --- then you're paying for capacity you don't need / won't use.

When it comes to the Bosch Inverter in particular if you need 4 tons, you pay for the 5 ton because they don't make a 4 ton. The 4 ton is a configuration set at installation.

The primary problem(s) with AC over sizing:

Short cycling. An inverter runs at very slow speeds, runs nearly all the time --- impossible for short cycling unless there is a problem with equipment (low on freon, condensate drain tripping, etc)

Not running long enough to remove humidity. -- an inverter will cover this in spades. It was "designed" for it.

So while you get better dehumidification with an Inverter you shouldn't view it as "control". Lennox may offer dehumidification settings via their proprietary control, just realize these kinds of things have limitations and often times limited to a 3-5 degree band from Temperature set point.

To actually control humidity, you would need a separate dehumidifier with preferably a humidistat to control it. This adds additional cost that you probably won't need. It is part of the reason I chose an Inverter for my house. I don't use any dehumidification type controls becase the nature of the inverter does this on it's own. If I feel a bit muggy, just drop the temp a few degrees --- because temp and humidity run independant of one another there are times of the year I have found where I have to go below my normal temperature set point for AC.

"Square footage is only one consideration when it comes to HVAC sizing and unless you are privy to a heat load calculation done on your home it may have come in at slightly over 4 tons and they just upsize it one more size and there is no such thing as a 4.5 ton residential AC unit."

As I understand it, an HVAC industry best practice is that a load calc is required to determine proper equipment sizing. Not doing one is akin to trying to sell someone shoes without measuring their feet.

There's nothing magical about "being privy" to a load calculation. My experiences, twice over, is that two different highly rated contractors at two different locations did one before finalizing their project bids. Both came up with outcomes that produced very differently sized equipment recommendations compared to what was being replaced.

Load calcs are required in California for building permits. They can be fudged, of course. Like many people, I try not to hire contractors who cut corners. If cutting a corner on a load calc is a contractor's standard practice, then sorry, I don't want to use you.

"As I understand it, an HVAC industry best practice is that a load calc is required to determine proper equipment sizing. Not doing one is akin to trying to sell someone shoes without measuring their feet."

Amen.

The problem with replacing HVAC equipment is:

1. HVAC replacement work is typically awarded to the low bidder. The better contractors--who would normally do calculations and do the job properly--won't typically invest much time on the front end of a prospective replacement job knowing they are not likely to get it.

2. The HVAC replacement contractor may not be well versed in performing load calculations.

3. The equipment replaced is typically replaced with equipment of the same capacity (see 1 and 2 above.)

4. The replacement may not be subject to permitting, and as such, even if load calculations and equipment sizing are performed, they may not be subject to review.

5. The condition of ductwork, air infiltration rate, etc. which are inputs to a manual J calculation may not be accurately assessed. This can lead to significant equipment sizing errors or missed opportunities for replacing oversized equipment with correctly sized equipment.

With respect to no. 5 above, the OP has an opportunity to have a blower door test and a duct blaster test performed and real-world values for the home's performance used as inputs for the manual J calculations. They also can use the results to inform air sealing and/or ductwork sealing work--two improvements which can reduce both the initial and operating costs of the HVAC system.

I don't remember what the measurement units were but the 3rd party HERS duct test, done after the install work was completed, required a reading lower than 25 somethings. Whether it was less than 25% leakage, or less than 25 cfm leakage, or what, I can't say. I believe what happens if the standard isn't met is that remediation work must be done to try to seal all readily accessible air path connections and openings - plenum connections, duct segment connections (typical of hard pipe or at flex connections to metal), duct connections at supply boots, etc. It's not required that walls be opened. Then the system is retested. If the standard still isn't met, then I believe the contractor files a signed statement that work was done on accessible connections ant the result is the best that can be so achieved.

Conscientious HVAC contractors not only seal their own work well but suggest sealing as an added service with installation as something irrespective of the testing that is an important thing to do for efficiency and comfort reasons. Ducts and their connections shift, detach, degrade, etc., over time and a thorough inspection with a pail of mastic duct sealant and good tape in hand is important to do.

@Elmer J Fudd,

I believe the duct leakage standard post construction is less than or equal to 4 cfm/100 sq. ft. of floor area when tested at 25 Pa (apologies for mixing English and metric units. I think we should go metric every inch of the way.)

With proper duct sealing, I think you should be able to get leakage to around 5% of total measured air flow rate of the system. There are products available for sealing on a retrofit basis without the need for access to the ductwork. Here's one such product:

https://aeroseal.com/residential/

It was done the old fashioned way with both of my jobs and both passed the test threshold the first time.

@Charles Ross Homes, so, you have first hand experience with this aeroseal product? Never heard of it before. Sounds interesting.

Forgot to comment on that - this product or one like it was shown some years ago on either This Old House or Ask This Old House. I asked each contractor about it and got eyerolls from both and something to the effective of "We don't do it that way".

@jrb451,

I have not personally used the product, but know others in my area who have. It works as advertised. Reducing duct leakage can reduce both the size of the heat pump or A/C unit and its operating cost.

@Elmer J Fudd,

I believe the Aeroseal product was featured on This Old House. For new construction, mastic or the appropriate UL-approved tape would be preferable, but those aren't always options on a retrofit basis where larges amounts of duct work may be inaccessible or where removal of insulation would add significantly to the cost.

There's nothing magical about "being privy" to a load calculation.

Companies don't do this for free, hand it to you so you can then go out hire someone cheaper. At least I wouldn't. I'll charge you up front for it, whether you do the job or not... I could care less. (you get what you pay for)

Maybe they provide it to you "after" the sale is complete. See you have to understand context here, not to mention some common sense.

You know like how you've mentioned to me before by saying include the cost of doing a heat load in your quote?

You get what you pay for? how about that, ever hear of that Mr. Fudd?

But what do we get for free? Read this board... I'm on here nearly every day, that's your freebie. On the house as it were. (some won't like that info, I'm ok with it... you know who you are. LOL)

I service the Katy, Texas area.

"The 3rd one at first said he would want 4-ton, but he did do detailed load calcs which took him nearly an hour, and he eventually settled on 5-ton also."

Presumably the contractor who performed the cooling load calculation showed it to the homeowner (which is different from giving it to the homeowner.) It's a marketable point of difference since the others didn't do the same type of diagnosis before prescribing a 5 ton unit. It makes that contractor more credible in my view.

"The 3rd one at first said he would want 4-ton, but he did do detailed load calcs which took him nearly an hour, and he eventually settled on 5-ton also."

Context: The 3rd contractor offered a 2 *speed* AC, not an inverter. Of which a load calculation would be *more so* required to perform properly.

I believe I explained the differences in the quotes further up, but of course you have to read...

The three quotes provided are not apples to apples quotes.

Heating and cooling load calculations should always precede HVAC equipment specification. Indeed the two are separate, but related, tasks and the ACCA treats them as such. The load calculation is a "manual J calculation." Equipment sizing/specification is "manual S."

The contractor undertook the load calculations as a marketing investment. Since he spent the time, it's a sunk cost. However, it sets him apart from the others and he should use it as a sales tool.

this summer on the hottest days, the current system was not able to keep the entire house at 72, it would start warming up a few degrees above target late in the afternoon.

The usual practice is to do the load calculations with the summer indoor temperature at 75, and the winter indoor temperature at 72. If I read between the lines, it appears your current 4 ton system could maintain 75 degrees on the hottest summer day. However if you want 72 degrees and plan to have several guests and cook at the same time, then moving up to 5 tons with a multiple stage system would not be unreasonable. You should ask the installer what indoor and outdoor temperatures were used in the calculation.

Regarding the oversize dilemma, the 20x36 intake seems to be perfectly sized for 5-ton.

Actually it is sized for a 4 ton system where the maximum air flow will be 1600 CFM. If the new 5 ton systems goes up to 2000 CFM then you may have a high static pressure. I filter size of 25X36 would be more appropriate in my opinion. I also recommend getting a 4 inch filter to minimize the air resistance.

"The usual practice is to do the load calculations with the summer indoor temperature at 75, and the winter indoor temperature at 72."

Residential HVAC work in California is subject to the requirements of the state's Title 24 Part 6. I believe the maximum heating indoor design temp is 68F and the minimum indoor design temperature for cooling is 75F.

I believe that permits are required for replacement of existing HVAC equipment in California when the value is over $500 and performance testing for duct leakage is required as well as remediation if leakage exceeds a certain value. If the replacement contractors do it by the numbers, there's a possibility that someone will review the calcs and limit the potential to oversize the equipment. Perhaps Californian @Elmer J Fudd will have more information.

Sorry but I have no further info to add beyond what I've already said. The best decisions I made were to hire what turned out to be very busy contractors based on reputations and a few references I checked. I asked a few questions about their bids before making the selections and I was out of the way but present as the work was being done on both jobs. I felt I was in good hands. When both contractors I chose (one in the Bay Area, one in SoCal) determined prior equipment was oversized and recommended sizing as prescribed by the load calcs, I knew I was in good hands. The passage of time and the (limited) changes of season have confirmed that the equipment installed is properly sized and they, together with the duct sealing, provide more comfort and economical operations than what it replaced.

At one home I had a cool experience with the building inspector who came for the final inspection. He had a copy of the HERS test with him, it had been transmitted to his office electronically. He said "please show me the compressor", I did. "Please show me the electrical panel". I did. He said something like "Everything looks good, thank you". I asked "Don't you want to go into the attic to see the new furnace, coil and connections?", he responded by saying " No, that won't be necessary. I did need to look at a few things but I know XYZ Company's work very well. It's one of the best in the area. We never have had an issue with any of their jobs".

I don't think Austin's SOPs would be successful over the long haul in my very competitive area.

The contractor undertook the load calculations as a marketing investment. Since he spent the time, it's a sunk cost. However, it sets him apart from the others and he should use it as a sales tool. (contractor bid #3)

True, but it proves my point why when you do it for free and assign no real value to it--- can you imagine running 40 of these in a week? It's only an hour, but a 40 hour man week after doing running 40 such calls. Imagine paying someone to do this for 40 hours, not making a single cent to cover that cost? Unbillable hours does what to a company Charles? If a contractor drained your bank account, produced nothing you wouldn't fire him? LOL.

Contractor 3 bid is $600 higher for a tier lower equipment than the Lennox that was quoted.

Sure California has alot of rules and regs for HVAC, some areas are similar. At the end of the day in this case all 3 contractors arrived at the same guess. But equipment selection is all different realms of performance.

It's not rocket science... I've been doing this job for 27 years. I know what being used in not so fun ways feels like, Charles Ross. I also know what unbillable hours does to my bottom line. Regardless what anyone thinks, I am in business to show a profit.

In 27 years can you imagine how many Heat loads I've done? -- not for sissies? -- more like not for people who think everything is free. (I'm not afraid to charge for my craft.)

Bids are offers to perform a scope of work--typically defined by plans and specifications-- which are provided to the bidders. What the OP has are proposals from different contractors for an undefined scope of work. The OP is left to decide which scope of work--however poorly defined--and which contractor to choose because it wasn't defined up front. At least one contractor helped to tie down the size of the equipment.

I think my analogy of selling a customer shoes without first measuring their feet is apt. There are different markets, different types of operators.

And the title of the thread "Sanity check..." should have disqualified at least one of the "usual suspects."

Ah, where's Capitaine Renault when he's really needed?