You have a lot of good questions and you are doing your homework. Good for you.

First thing is see if you can get a cash settlement from the warranty company. If you can you can put it towards purchasing an HVAC system from a good installer.

Here are some answers to your questions:

1. SEER/EER measure the efficiency of the AC. The higher the rating the lower the operating cost. This assumes the AC is properly sized and installed. Multiple stages and variable speeds are more about comfort. There may be some small of amount of energy savings.

2. It depends on how long you plan to live in the house and how high are you energy costs. If you never realize a return on investment, then it doesn't make sense to spend the extra money on high efficient equipment.

3. You are in a hot climate with mild winters. The AC size is selected by your cooling load. The furnace should be sized by the heating load, but in your case you may be forced to buy a larger furnace in order to supply enough air for the condenser. Some good equipment selection will minimize the furnace over sizing.

4. I don't see why zoning would require a smaller condenser. You have to assume all zones will call for cooling at the same time. Whoever said this is not good at zoning.

5. The Nest thermostat may have problems working with some types of equipment. For variable speed and communicating systems you are better off buying the manufacturer's thermostat.

6. Annual maintenance fees are not worth the cost in my opinion. You are better off paying for annual or biannual service as needed.

You HVAC system is 19 years old. You should be looking to replace the furnace, condenser, and coil.

It would be in your best interest to find a contractor who will do a load calculation. I know it gets hot in your part of California, but I am not convinced you need a 5 ton condenser. Most homes don't have a large enough duct work to handle the air flow for 5 tons of cooling. You are being quoted 110K BTU furnaces which is grossly over sized. That is because they are needed to service a 5 ton condenser which may also be over sized. Find out if Title 24 requires a load calculation in order to qualify for rebates. You could do a calculation yourself for software that costs $49, or you can hire a professional to do it.

As far equipment you have been quoted, Payne is typically builder's grade equipment. The Rudd may potentially be good, but I am not familiar with all their models.

The Goodman equipment has a lot of good features, but there is a lot of disagreement on this forum about the reliability. I see the Goodman quote has proposed an Aspen coil. That is a red flag for me. You should not accept any quote that proposes using a third party coil especially for the prices that were quoted.

I think these contractors are either playing possum (with the expectation that more work gets mandated later) or expecting to skirt under the rules.

Full permit compliance requires HERS testing and (I believe) load calcs. This is likely to be a house in a developer-built area. It wouldn't be surprising if both the ducts and insulation need to be enhanced/repaired, unless done by a previous owner.

For now, I would focus on getting a clear handle on what work is REALLY needed, then get comprehensive quotes that include everything. HERS testing is done by a third party, not the HVAC contractor.

Mike_Home - Thank you for the answers and advice. Here are some responses and follow-up questions.

1. SEER/EER - your answer is what I had been slowly understanding that these numbers are what drive the efficiency numbers. Rough calculations comparing my older 10 SEER unit to a 14 and 16 SEER unit plus using 1 year of energy bills, show a potential electricity improvement of $184/year for the 14 and $238.31 for the 16. Of course this is all dependent on a quality install as well as proper ducts, etc. as you've outlined in other points.

2. Payback will be uncertain as I was relocated for work. Not sure how long we'll be here and at this point, the energy savings per year is still important.

3. Understood. Before my research, I didn't realize that the furnace played such an important role in airflow.

4. My zoning explanation might have been poorly stated. The gist of what was mentioned, was that based on proper zoning, the more efficient airflow distribution within the home may allow for a 4 ton condenser. The condenser potentially wouldn't have to push air through all of the ducts at the same rate. Does that logic track with your experience?

5. Appreciate thermostat advice and handling all the features, etc.

6. The annual maintenance contract was from the contractor providing the detailed Goodman quotes. Participating in the yearly maintenance contract covers 100% of repair costs (Contractor backed, not OEM), includes a 10 year replacement warranty, and there are no dispatch or service fees for service calls. The replacement warranty is the full replacement of the failed unit rather than just repairing under the 10 year labor warranty with Goodman. If I don't do the yearly maintenance contract, there is no replacement warranty. Ever heard of this?

The contractor (Goodman quotes) may have mentioned "calculations" at one point but I don't remember hearing about them doing a manual "J" load calc. As far as I can tell, Title 24 doesn't require the J calc. It does require a duct leak test performed by a certified 3rd party HERS testing company. This is required on ALL HVAC projects in CA. Rebates are only available as part of CA's Home Upgrade Program. This program has required testing and upgrades on items like ducts, whole home envelope, attic insulation, etc. I will go back to two of the contractors and ask them about performing the calculation.

I am looking to replace the whole system at this point to make sure the equipment is compatible and most efficient.

Goodman is making me increasingly nervous, especially with the Class Action lawsuit that was just set back last week based on a judge's ruling... As for the use of a different coil with the Goodman equipment, it seems to be very common with Goodman quotes (based on board postings like this). I think there is a relationship or commercial connection between Goodman and Aspen to drive the high use with Goodman systems.

I don't know the true specs on the Ruud equipment, I was guessing a bit; I will ask for the models, etc.

Thanks again!

Elmer - Thank you for the response and advice. Here's some follow-up and answers.

1. The contractor assigned by the warranty company was definitely just looking to slap in some hardware and take the money. The other two were more thoughtful in their initial assessment visits and the conversations.

2. All bids definitely contained a line item that HERS is by 3rd party. I could let them arrange it or I could do it on my own. I've never read that a load test was required by permit, but that doesn't mean it isn't the case. I know that the ducts upstairs need to be secure with mastic, etc. so that is a given that ducts need to be modified to some degree (which potentially helps with the Home Upgrade program eligibility requirements.

4. My quandary in determining what REALLY needs to be done is also compounded by the rebate program. The potential exists that the requirements to get to >15% reduction in home air leakage may severely eat into the rebates received...

I appreciate the advice!

"... the more efficient airflow distribution within the home may allow for a 4 ton condenser. The condenser potentially wouldn't have to push air through all of the ducts at the same rate."

The size of the condenser is determined by the cooling load. The calculation includes duct losses which adds to the cooling and heating load. The loss with be greater the ducts run through unconditioned space and are long in length.

It doesn't make sense to me how adding zoning can reduce the cooling load. The condenser has to be able to service all zones at the same time, and the air flow has to be reduced so the smallest zone can handle the air flow. I get suspicious when contractors make statements like this.

Many contractors use a rule of thumb using the area of the house and equating that to the number of cooling tons required (ex: 500 sq. feet per ton). That is not a calculation and almost always results in over sized equipment.

Goodman as well as most manufacturers provide a 10 year parts and one year labor warranty. A maintenance contract is not required, but you also can't neglect the equipment and expect it be fixed for free under the warranty. This dealer wants to provide his own labor warranty providing you make 10 years of payments to him while he stays in business. You would have to calculate the costs to see if it worth or not. Most times it is not.

Many contractors like to quote Aspen coils because they are inexpensive. The savings is small and not worth it in my opinion. The efficiency ratings using third party coils is questionable. I have read they are calculated by simulation and not actual testing.

Mike:

When I asked about the size of equipment and J calculations, the contractor stated "Yes the load calculation called for 4.9 ton @ 25% loss under manual S that we use in this climate zone." I've done some reading online and it appears the S calculation may be a more robust calculation than a J calc? Or should both be used?

I was surprised by the response when I was asking for a more detailed breakdown of the basic HVAC replacement work: "The program we use doesn’t break it down, I just select check off items like horizontal 90%+ furnace, horizontal evap coil, install and it totals a price with labor, overhead, and profit." Is this common that there's just a "package" cost as if I'm selecting different car wash options?

Here is what he said about the dual zone components and cost: "I input 8 dampers, 1 zone control board, 1 transformer, 1 discharge air sensor, 1 roll of control wire, 1 nest gen3 stat, 50’ stat wire, and misc install items, $1,708.00, 16 man hours Labor, overhead, and profit $1,488.00." This is much more specific that the hardware quote, which makes me suspect his "program" is a goodman program?

His comment on using Aspen was that it was supplied by his distributor and "matched to get a little higher efficiency" (that doesn't make sense based on your previous comments about matching equipment) but also that the ceiling access to my attic prevents using a Goodman coil based on size.

I agree with your comment on the extended warranty not being cost effective. It's a $235/year cost. And paying for 10 years to maintain a replacement warranty on single speed AC (2 speed is 10 year factory replacement warranty) doesn't seem like a wise investment.

Final item I question is reusing refrigerant lines. They plan to reuse as long as no leaks. Is this wise? I've read other notes on these boards that they should be replaced.

Thanks again for all of the excellent advice and hope you've had a "labor free" Labor day weekend.

Elmer:

I appreciate your points and advise, especially now knowing you're speaking from experience in my climate conditions. And, you wouldn't be the first person to suggest I get mired in the details... All I can say is that I've been lucky to have this recent bit of mild weather, otherwise I'd be a dead man!!

More and more, I'm leaning away from the rebates and focusing on the right cooling equipment as you suggest. The amount of retrofit and rework to pass is potentially very expensive. Plus, I agree that my cooling bills will be the most impacted by upgrading vs. HE heating equipment.

I'm now working to better understand between to two local contractors that I've talked to based on recommendations. Would you mind sharing the name of the group that you used? They may be local to you but perhaps they service my area as well. As you said, it's always smart to go with recommendations.

Have a great labor day weekend.

"Yes the load calculation called for 4.9 ton @ 25% loss under manual S that we use in this climate zone."

I don't know what that means. The loads calculated with the Manual J calculation become the inputs to the Manual S calculation. I have never done a Manual S, but I believe it is used to confirm the selected equipment meets the heating and cooling loads without being over sized.

Is he saying the Goodman coil won't fit through the ceiling access but the Aspen coil will? The furnace is even larger, how it that going to fit?

The refrigerant lines can be reused if they are the proper size and they are flushed properly.

BMW (great cars),

I'm at the southern end of the Bay Area and Brentwood is easily a two hour or longer drive during weekday commute hours. My contractor stays very busy just working locally - I had to wait several months before they could schedule my job start. Unfortunately for your needs, I know they don't go up to your area.

You are in a primarily dry but hot cooling area, as you say, and you'll find that winters are mild and not very wet. Especially compared to anywhere in Ohio.

I think with the right contractor who applies his knowledge to the house's requirements and the right mix of work (not just plug and play), you'll be happy. I wanted to keep it simple with properly-sized mid-range models of good brands but without bells and whistles. For me, it's so far, so good. You'll make the choices that are right for you, following the advice of a contractor you can trust. They are out there, it sometimes takes some looking.

Good luck.

Elmer, well, it was worth asking!

You're right about the climate, that's been the best thing so far, even with the heat. I prefer dry heat to humidity, so it's all good for me.

My preference is to get the most bang for the buck with equipment as well. The majority of my improvements and savings will come from simply upgrading to newer equipment; anything else is quickly diminishing returns for the cost to achieve them.

Thanks again!

Mike, I believe you're correct that Manual S is used for equipment spec after Manual J (only know because read up on it).

As for the dimensions, that's a valid point as I think the depth on at least one furnace is over 28 3/4".

The saga continues...