Several questions.

What size and efficiency are existing furnace and AC condenser to be replaced?

Any specific issues and/or problems with existing system?

What size is the Carrier furnace that is quoted? You will note the Lennox furnace is a 135 KBTU which on the surface seems ridiculously oversized.

Lennox dealer has quoted a 4 ton condenser, Carrier a 3 ton condenser.

Any living area used for basement? If so basement is below grade? Basement ceilings are insulated ? R rating?

Has either dealer performed a load calc in writing both cooling and heating and provided a detailed written copy for your review?

Do you know your all inclusive rates for both nat gas price/therm and electric price/kwh? Generally heat pumps for NY metro area are not recommended when nat gas service is available to residence.

Any hot/cold spots in home? If so, these should be pointed out and dealer should make recommendation for improvement. I always recommend a thorough ductwork survey. Home has adequate returns?

Attic insulation should be brought up to code for NYC. I would think R40+.

I generally prefer Carrier over Lennox and I would upgrade the outside Carrier condenser to a better model. Two stage is fine if it fits your budget. Not necessary though.

I would lean on your dealer's advice on the humidifier taking into consideration cost, your routine maintenance and its frequency, time, and ease of service. You certainly don't want to call the dealer to perform humidifier maintenance or to change an air filter. Stupid.

These are a few ideas and observations.

Post back.

IMO

I am in central NJ and know the high cost of electricity surrounding the New York City area. There is little or no savings in operating a heat pump versus a 96% efficiency natural gas furnace.

I have the Carrier Infinity 2-stage AC condensers. I purchased them 4 years ago. In my opinion they do a great job of lowering the humidity. I am able to set the thermostat at 78 and achieve a humidity level in the upper 30s to lower 40s. It is very comfortable with these settings. The other benefit of running in the low stage is that you don't realize the AC is running and there are no cold drafts. There is a small savings in setting the thermostat setting higher, but not enough to justify the extra cost. It is more of a comfort feature.

You should upgrade the attic insulation before the hot weather starts. Tell the contractor your plans of the insulation upgrade so that it can be factored into the load calculation. I would expect the furnace size to be 80,000 BTU. The 2-stage AC only comes in whole ton sizes. The 3 ton size should be adequate, if not you will have to move up to 4 tons if you want the 2-stage AC.

Are you sure you need a humidifier? The air dries out in the winter because of outside air infiltration. You are better off spending money to tighten the house then on a humidifier.

Thanks for the quick responses!

The existing furnace is an oil-fired York, 125 KBTU, which is at least 30 years old. I have been told it's horribly inefficient, but I don't know the number. The AC condenser is 3 tons and 25 years old (also not efficient). The house should probably have 2 zones (especially to deal with better cooling the second floor in the heat of summer), but I have been told that's not possible (at least not for a reasonable price). Otherwise, there are no noticeable issues with the current system, other than those endemic to scorched air heat. Each room has at least one supply vent and one return.

The basement is below grade and is used as living area. There are two supply vents and one return in the basement area. There is no insulation between floors, but the basement walls are insulated (R-7.5). Beefing up the attic insulation is on the near-term to do list.

The house currently does not have a humidifier, and while no one is suffering nose bleeds, the air is dry. So, I thought a humidifier would be helpful. I would definitely like to tighten the house (and new windows may be on the radar in the near future), but given that it is an older home, I think there is only so much that can be done.

The Carrier dealer said the furnace would be no more than 100 KBTU, with the final determination after the house is measured and a load calculation performed. Both companies will also do a whole house energy audit prior to commencing work. So I would assume (and hope) the Lennox dealer will modify his numbers accordingly after the load calculation and energy audit.

Our natural gas marginal price/therm is $0.83
Our electricity marginal price/kWh is $0.22 for on peak, and $0.07 for off peak.

With regard to the Carrier condenser, what makes the 24ANB6 superior to the 24ACC6?

I know a lot of people on this forum prefer Carrier over Lennox. All else equal, I have no problem going with Carrier (I know the Infinity controls are fantastic), but there is a $1,500 price difference...

Thanks again for your help.

The 24ANB6 has an sound insulation blanket so it is quieter than the 24ACC6. Otherwise I think the internal machinery is the same. So if the quiet operation is not important to you then its not worth the $1500 price difference.

Both of these models are single stage condensers. However the 24ANB6 is supported by the Infinity controls, the 24ACC6 is not.

And assuming you are going Carrier which I would recommend, I would get a price also on the Performance 24ACB7(24APA7) two stage condenser that is Infinity control supported. Of course you want the best applicable Carrier evap coil for performance/efficiency numbers.

I would hold off on deciding condenser selection until I saw in writing both heating and cooling load calculation.

By changing from forced air oil heat to forced air nat gas heat, you should see a nice payback probably under 10 years. Very few retro installs have that benefit. I would not be surprised to see the 80 KBTU furnace model as satisfying and meeting heat load.

IMO

This post was edited by tigerdunes on Sat, Mar 30, 13 at 12:14

I will inquire regarding the 2-stage Performance condenser. Thanks.

Tigerdunes, you have a clear preference for Carrier over Lennox (I have read many of your posts on other threads indicating so, as well). Can you please explain why this is the case?

Also, any further insight on the economics of a heat pump option? From last month's bill, natural gas marginal price/therm is $0.83; electricity marginal price/kWh is $0.22 for on peak, and $0.07 for off peak.

Many thanks!

Toolman

There are three major leading brands in the residential HVAC marketplace plus their associated sister companies. Carrier/Bryant, Trane/AmStd, and Lennox. These are the players and of course the ones with the large advertising and product research budget. Everyone has their favorites. I have mine, you have yours. It's my opinion that Carrier and Trane top the list with Lennox a distant third.

There are many secondary brands that are fine. There also are several brands that I would not recommend for a doghouse. These are sold more on price than quality and usually attract a low end install

For a retrofit upgrade that you are considering there are three parts to a successful new installation.

1.Correctly sized and quality HVAC
2. The install itself by qualified and experienced dealer and their staff
3. Perhaps the most overlooked and disregarded is the ductwork system.

I am very familiar with heat pumps and they can be a great product for the right application. For your location though along with high electric rates, I would not consider a HP.

IMO