Where in NJ are you located? If you are in or near Mercer county I can recommend a Carrier dealer who will properly size your equipment with a load calculation.

You have a lot of good questions. I will try my best to answer them briefly.

1. The plenum should only be changed if it needs to be modified to accept the new furnace.

2. It is a no brainer to go to high efficiency.

3. Both the Infinity and Performance furnaces are very good. The 59MN7 is best since it can modulate to many speeds to maximize comfort. You will have to decide whether some comfort features are worth the extra cost.

4. I recommend the 4 inch media filter. It lasts longer is less restrictive to air flow. A MERV 8 filter is fine for most people.

5. Electronic air cleaners are overkill.

6. The existing humidifer could be used. It can be replaced in the future when it fails.

7. Carrier provides a one year labor warranty. You need to find out who is providing the additional labor warranty and if there any maintenance contracts required.

8. If you get an Infinity furnace then you should get the Infinity controller.

9. A 120K BTU furnace is very oversized for your house and climate. I would think an 80K BTU furnace at 95% efficiency would be appropriate. You need to find a contractor who will do a load calculation to confirm the size. I also think the 5 ton AC is oversized.

10. The best time to a HVAC equipment is early spring and early fall. This is when Carrier and other brands offer rebates. I recommend not buying now if you can hold off until spring.

I am not a fan of the NJ Clean Energy rebate program. You are usually quoted inflated prices and then get money from the state. The savings are small if any. The 10 year interest free loan may be worth it to you. You have to decide after you run all the numbers with and without the program.

Running a duct in a basement is relatively. I am not sure why you were quoted $3K. This this include opening walls and repairing sheet rock?

Hi Mike,

Thanks for the quick and through reply. Some follow-up questions:

I'm in Hunterdon Cty so would the Mercer dealer travel here? I would like to have the installer perform the annual maintenance so I'd want to make sure travel wasn't an issue, not to mention I'd need prompt service if I had an emergency.

I'm still foggy on the new plenums, which represent a significant gap between the 2 quotes. Can the salesman (former repair guy) not tell beforehand whether they need to be modified to accept the new furnace? Although perhaps Dealer A felt yes and Dealer B no hence the quotes I received. For most installs, are the plenums typically kept or replaced? If I were to go with Dealer B, might he tell me mid-job that I need new plenums?

How to tell if/when a humidifer has failed? It doesn't seem to make much noise from what I can tell.

I was quoted a 5 year Carrier labor warranty? Is that not accurate?

The 5 ton condenser replaced the original. Do builders usually just throw a big size in without consideration as to whether it is too much?

How much better might the Carrier rebates be in the spring? i'm not even sure if the 2014 rebates have expired.

The NJ Clean Energy rebate (WarmAdvantage) looks like $500 for 95%+ and Energy Star qualified. Isn't that free money to take advantage of or is 0% financing some sort of alternative? I wasn't looking to finance.

Trying to get more details on the basement install procedure that makes up the $3k quote. What is the standard process for adding heat to the basement via new ducts?

You may be within the service area of the Carrier dealer I use. Send me an email I will provide the contact info. Set your account so that I can see your email address, otherwise I won't be able to reply.

I participated in the Warm Advantage and Cool Advantage rebates 5 years ago. It is free money if you qualify. The program I was referring was the one where you have spend a lot of money upgrading insulation and sealing in order to qualify for the rebates.

You may have misunderstood the labor warranty. The dealer may provide the first 5 years as part of his standard quote with an option for another 5 years. You should ask about this.

The rebates of an Infinity furnace and AC are $800-$1200. But you don't get a new condenser it will be less. Be aware the dealer has to pay half the rebate cost so you may or may not see the full amount taken off your quote.

Going up in size in a condenser gets to be expensive so a builder would typically not oversize a condenser. If your house has vaulted ceilings, skylights, and a lot of windows facing south and west then a 5 ton may be appropriate. The problem is most houses don't have the duct work big enough to handle the air flow required for a 5 ton condenser.

The salesman should be measuring the plenum to see if it is big enough to handle the proposed furnace. The 120K furnace at 95% will provide more heat than your current 140K furnace at 78%. The plenum discussion is a moot point since they are both quoting a furnace that is too big!

Did you tell them the current furnace short cycles? If you did and they ignored it then you should be talking to more contractors.