I'm currently in the process of closing on my first house, and I recently had an inspection done. The inspector provided the following statement regarding the HVAC system:

The temperature drop measured across the evaporator coil of the air conditioning system was 14° which is outside the normal operating range of 15 to 22°. Evaluation and repairs are needed.

At this point, we decided to get a HVAC specialist to take a look, these were his results:

Details of the HVAC system:

  • Condenser: 2.5 ton Trane, M2AC303B1000AA, S# 141560411M, 8 years old.
  • Furnace: 3 ton TRANE, TUE080A936L2, S# 2385RPP2G, 21 years old.
  • Coil: 2.5 ton TRANE, TXC031S3HPC0-, S# 5194LGT5G, 18 years old.

HVAC Specialist's Notes:

  • System is undersized for the residence.

  • Furnace and evaporative coil are beyond their typical economic life.

  • Recommends replacement and correction of any other code or installation issues.

  • Condensate drain was clogged and leaking onto the deck under the furnace (corrected during the inspection).

Estimates for various services:

  • Service system post-move: $150.00

  • Sediment trap in gas line: $75.00

  • Trimming wood from vent at the roof: $75.00

  • Total repairs: $300

  • Replace existing system with a new 4 ton 15 SEER system: $12,500

  • Replace existing system with a new 5 ton 15 SEER system: $14,000

The inspector recommended a load calculation without considering additional factors and estimated 400+- SQ FT per ton, which translates to 4.8 tons of cooling.

Given these findings, I'm looking for advice on the following:

  1. Should I go ahead and replace the entire HVAC system based on the inspector's and specialist's opinions?

  2. Would it be wise to bring in another technician for a second opinion?

Please let me know if there is anyway I can become more knowledgeable in this topic, I'm first time home buyer and struggling along this process... It's a lot...

Edit: This is for a 2000 sq/ft home in Texas.

  • 2
    It would be wisest to be asking the seller for a price reduction to cover the costs.
    – Tetsujin
    Sep 8, 2023 at 17:35
  • 4
    Always get more than one quote for major services like this. That's the only way you'll know if the price you just got is reasonable for your area. At 18 & 21 years, your equipment is old enough to vote & drink, and get replaced. You're going to need to do that sooner rather than later, so negotiate the price down to leave you with some money to do so. If you have the seller replace it, it'll be the cheapest thing he can find and probably not the quality you'd like.
    – FreeMan
    Sep 8, 2023 at 17:38
  • 4
    Depends on how much you want this house vs how much the seller is willing to come down on the price. This report would presumably allow you to claim the entire repair allowance in the contract whcih the seller presumably assumed would be claimed. A 2.5 ton system where 4 ton to 5 ton is called for seems like a deliberate choice to be substandard. You might be justified in walking away and getting your deposit back. Sep 8, 2023 at 17:50
  • 4
    If the house has been heating and cooling well with a 2.5/3 ton system, I would really want to see someone do a Manual J calculation to size properly before just throwing in a 5 ton. It's really easy to end up with too big of a system that does a great job of removing sensible heat and a bad job of removing latent heat, so the place is clammy and uncomfortable. For cooling, at least, I would always prefer to see slightly too small over too big.
    – KMJ
    Sep 8, 2023 at 18:14
  • 2
    How big is your house? 5 tons seems awfully big. And where are you located? Gulf coast is a lot different than Maine.
    – SteveSh
    Sep 8, 2023 at 18:43

4 Answers 4


There are a bunch of different issues here. But the bottom line is that much of the system is old, and therefore likely to need replacement in the not-too-distant future, and relatively inefficient. Possibly undersized as well, but that is harder to tell for sure. But it is basically working right now, and that's what really matters.

If I were a seller and the market was good, I would almost certainly not agree to a $10k+ credit for new HVAC. It would reasonable to ask for $300 to cover the minor issues. If they agree, great. If not, I wouldn't give up just because of $300 - not a big deal in the grand scheme of things.

Then after you move in and get the basic service done:

  • Get the first company to give an estimate for a higher SEER system and for a heat pump rather than furnace + air conditioner.
  • Get at least one more estimate for comparable equipment.

and then decide what to do. Which for most people will be: wait until there is a major problem and then replace the system. Hopefully you can get another couple of years out of it.

  • 1
    Minimum SEER by law right now is 13 or 14 depending on region. Minimum goes up next year to 14 or 15. So basically 15 is just above the minimum. You can get MUCH higher, but you pay for it. To the environmentalists it is "most efficient at any cost". To me it is "Do the math" - i.e., figure out approximate energy costs for low vs. high efficiency systems over the expected lifetime of the system. A heat pump is essentially an air conditioner that can be "reversed" so that it can heat as well as cool. 30 years ago they didn't work so well. Now they are so efficient (the good ones at least) that Sep 8, 2023 at 19:21
  • 1
    they can be much more cost-effective - in terms of energy costs - than a natural gas furnace - even though gas might be burned to make the electricity that runs the heat pump. Plus they can work when it gets really cold, which was not the case a few decades ago. Disadvantage: in a blackout you can run a central natural gas furnace on much less electricity from a generator than you would need to run a heat pump. Sep 8, 2023 at 19:23
  • 1
    Where in Texas is this property? I regret not getting a heat pump 3 years ago when we got this new system. I just had them replace the existing 3.5 ton system (30 year old R-22) with a 4 ton of roughly the same mid quality 17 SEER 1-speed air handler. and another natural gas furnace. We were very hot and didn't want to ponder alternatives. If you do op for a heat pump there would be an electric resistance backup for very low winter temps. This would probably require a new 240 V 40 A or more circuit to the air handler. $$$ We have a 6" thick pleated paper SpaceGard filter unit. $$ worth it IMHO Sep 8, 2023 at 20:07
  • 1
    The good news is that with a really good heat pump that backup heat will typically only need to run a few days a year, unlike the systems from a few decades ago. Sep 8, 2023 at 20:10
  • 1
    Same—as a seller, if the system is working, I'm not offering a huge discount for the buyer. It's pretty much as-is. You don't like the price, walk away.
    – Huesmann
    Sep 9, 2023 at 14:27

The key difference here is

It is working right now and you are in control negotiating the prices (not in a hurry)

That will change drastically once the system breaks and you are in the must do now mode.

As the experts say, you got more than normal lifetime out of it.

I would not wait till it breaks, but would negotiate new system now.

As for capacity, it is a bit of mystery going from 2.5 T to 5 T, how did the 2.5 Ton managed.

Word of advice, be careful with high SEERS, it is not always worth the investment, the ROI is terrible. The SEER has noting to do with cooling, it only supposed to save you money on electricity. In some cases it will take 10 Years to recover your investment.

  • @terrabl that is correct, so your 15 SEERS is just fine, do not need 18 or even 25 SEER, just waste of money.
    – Traveler
    Sep 8, 2023 at 19:27
  • 1
    Energy efficiency is not purely a matter of "need". It is arguably (though personally I am not so big on this) a question of proper use of overall resources and definitely a question of $. Do you use incandescent bulbs or LED bulbs? There it is extremely clear - the energy savings are so dramatic that LED bulbs are unquestionably cheaper to buy+run over their typical lifetime than incandescents. With low vs. high efficiency A/C and the related high efficiency heat pump vs. natural gas furnace the equation is not so lopsided. But it is still something to consider. Sep 8, 2023 at 20:09
  • @manassehkatz-Moving2Codidact please delete your comment, it is all wrong or use actual numbers to justify
    – Traveler
    Sep 8, 2023 at 20:38
  • Are you questioning the efficiency of LED vs. incandescent? Or just the heat pump vs. furnace? Sep 8, 2023 at 20:39

This is an opinion based, so the question may be closed.

Since the specialist found that the system was undersized and most components were quite old, I would recommend a system replacement.

If the sale has a contingency based on the results of an inspection, you may be able to renegotiate the contract to recover some of the expense. The contract may be "as is" meaning the sellers do not want to do any repairs. A realtor may tell you the sellers won't pay for anything, however remember anything is negotiable in a purchase contract. Further, if financed the lender may not be willing to close the loan without the home having a proper HVAC system.

This means you have to decide what you want to ask for. It can be nothing or for the sellers to pay for a new system. The best case is to ask the sellers to pay for a new system. Not to reduce the price. Unless you are paying cash, the price of the system will have to be paid out of your pocket.

  • 1
    Thanks for the insight, I wasn't sure where else to ask this, I tried reddit but didn't get any response, I'm glad I got some people to help me feel vindicated in what I'm asking the sellers. It's hard doing this the first time so any help I can get is greatly appreciated from myself.
    – terrabl
    Sep 8, 2023 at 17:45

Sometimes inspectors' reports have to be taken with a grain of salt. If your inspector had returned a report saying "everything looks great!" and then later a friend of yours asked for an inspector referral, would your friend be impressed by the review "yeah, this inspector I used was really nice, but he didn't find anything at all wrong with our house"? Or would your friend be more likely to pick a different inspector who got a review like "well, OUR inspector returned a report 15 pages long with all kinds of defects noted!"

You can see that an inspector has at least a little incentive to perhaps be a little bit alarmist in his report so that the customer (the home buyer) feels like they've gotten good value in purchasing his services. It's also worth noting that many inspectors have never worked in the trades, so they do not have the depth of experience that a specialist who has been in a trade for even just a few years will have.

A reading one degree below a range that's just 7 degrees wide, without assessment as to whether outdoor conditions, cleanliness of the air filter (ie adequate air flow), or other effects might have caused the discrepancy, isn't actually all that valuable.

A load calculation is a nice thing on paper, but it actually entails quite a few assumptions that can undermine its usefulness. The very best guide in an existing building like yours is this: has the existing system historically gotten the job done? An arbitrary increase from 2.5T to 5T based solely on the 1T per 400 sq ft rule of thumb is rather sketchy. Is half of the 2000 sq ft basement? Basements ordinarily aren't counted as cooling load. Such an increase should not be undertaken without also analyzing the duct system to confirm that the ducts are large enough to accommodate the corresponding increase (doubling) of air flow required to utilize the additional cooling.

Your specialist is right that the furnace and evaporator are "beyond their typical economic life." But I've replaced furnaces that were 30 and 40 years old; age alone doesn't tell the whole story. Especially for the evaporator coil, which is non-mechanical and literally just sits there just like the wiring and plumbing in the house. The fact that the condenser is just 8 years old is reassuring. Most condensers (and furnaces) I've replaced were 18+ years old.

It sounds like your HVAC specialist has given reasonably good advice. The inspector's report may have led you to excess worry and concern.

  • Thanks for the insight, that's a good point about the inspector...
    – terrabl
    Sep 8, 2023 at 21:13

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