Give furnace model and gas prices. You will probably get better bang for the buck from improvements in the house envelope. Make sure that the builder meets benchmarks for air leakage in envelope and ducts as construction progresses. I hope that ducts are inside the envelope where they should be.

Meeting with the HVAC guy on Tuesday. I will get the model numbers then. He uses American Standard. If I am reading my gas bill correctly it looks like I pay $.39 per therm for natural gas delivery and $.47 per them for gas supply. For a total of $.86 per therm? Gas usage will be hard for me to estimate because we are moving from a 4800 sqft home with 4 people to a 3000 sqft home with 2 people.

Also, have you looked into efficiency rebates offered by your utility and/or state? I'm not familiar with NY, but in NJ they kick in for 95%, not available below that. That could kick a couple hundred off of the upgrade.

In order to get the extra 5% out of the more efficient model, it will have to be sized correctly and installed correctly. If it is not, you might get nothing out of the extra money.

You might consider hiring an energy expert to help you through design decisions and checking the construction for proper air sealing.

Freeoscar - I did a google search and found a rebate program from my utility (National Grid) that looks like it would pay $450 of the upgrade cost. Seems too good to be true but I will talk to the sub contract and then call them. Thanks!

NYS Rebate

Mike_Home - in my last house (bigger with more people) our highest bill was in February where it was $120 or so for gas supply and service and then it plummets in the warmer weather. And of that usage, some of it is for hot water and not impacted by the furnace decision. So I can see how the gas savings alone is not a good enough reason to go up 5% in efficiency. I'll see if the furnaces have different features.

You would also qualify for a $150 federal tax credit if the AFUE is 95% or higher.

Look into NYSERDA programs

"Look into NYSERDA programs" - Looks like they are income based.

Met with the HVAC contractor today. We are going with the American Standard S9V2. I think 80K BTU. It is 96% (not 95%) efficient. It is 2 stage - which is a step up from the standard 90% efficient one that is one stage. The upcharge is $850 but as someone pointed out, there is a $150 federal tax credit (confirmed by my accountant) and a $420 rebate from my utility company (National Grid). That brings the cost down to $280 which is good enough for me. The only catch is that I will need a receipt from the HVAC guy showing that I purchased the furnace (not the builder). We are working on that detail. Any thoughts or comments would be appreciated.

A very good choice...make certain you get the correct size furnace and the matching two stage thermostat...

IMO

I'd ask to see the heat loss calculations. If you have that, you know that they have at least gone through the motions of sizing the furnace properly. You want long run times and not a lot of bang on and bang off like a traditional furnace.

On the furnace size, this sub contractor did not do any calculations. When we were talking he looked at the construction manager for the development and said "I think this is an 80K btu unit right?" (I could be wrong on the 80K but you get the point). This development has 10 or so approved floor plans and they have already built mine elsewhere so I am sure that they will tell me that it was sized when the floor plans were designed. Which may be true .

It looks like this unit only comes in 60, 80, 100 and 120K btu so whatever the manual j calculation calls for is not likely be coincide with one of those unis. So assuming a reputable and experienced HVAC contractor and a pretty basic home how hard should I push for him to do the calculation? I am trying to pick my battles?

The sub volunteered that they needed to use the blah blah blah thermostat otherwise the unit will always come on at stage 1 and then go to stage 2 after 5 minutes. He mentioned that on a day like today (cool fall day) it would probably run only at stage 1.

The design winter temperature in Syracuse is 2 degrees F. It would seem an 80K BTU furnace for a 2000 sq. foot ranch house with low end windows would be about the right size. New construction should always have a load calculation. HVAC sub contractors are not well paid so don't be surprised if a calculation is not done. They may claim it was done your you model house. You should ask for documentation.

You want the thermostat to control the staging and not the furnace. When the furnace does the controlling, the furnace starts in the low stage and then go to the second stage after a fixed number o minutes. It will not go down to the lower stage during the cycle.

When the thermostat does the staging, the furnace will usually start in the low stage and then move to the high stage if needed. It will then go back to the low stage before shutting down at the end of the cycle. Every 2-stage thermostat works a little differently but that is the general operation.

I don't know that much about furnaces. With newer types of boilers and heat pumps that operate at more than one output, there is a penalty to running at high output. In other words, they are more efficient at lower output. If they are not set up correctly, they will not run efficiently. In incorrect thermostat is one way to set up the system poorly.

Another factor in efficient operation of these two-, or variable-speed systems is that recovery from set-backs often puts you in the inefficient zone of operation (highest output). For that reason, set-backs can be counterproductive. Whether they are depends on, outdoor temp, characteristics of the heating and cooling equipment (and their controls), characteristics of the structure, and duration of the set-backs.

Mike, I think that you need some editing in the first sentence of the last paragraph of you post furnace x thermostat. Do good, efficient modulating furnaces have outdoor sensors (resets) and allow settings for their use to control firing rate?

Whats involved in a load calculation? I have seen spreadsheets online where u enter data. Can i do this myself?

Ionized_gw,

Thanks for pointing out my typo. I tend to type fast and make mistakes.

The higher stage may be a little more inefficient than the low stage. I would think the minimum for any stage has to be the rating of the furnace. I am not sure what the rules are about this.

I use setbacks in summer and winter and for my house. In my opinion it saves a lot of money.

Most 2-stages thermostats have the ability to add an outdoor temperature sensor. The outdoor temperature is supposed to be used as an input as to when to change change stages. I have never seen this explained in any thermostat literature. It works differently from a boiler reset which causes the boiler to fire at a lower temperature on mild days.

You can do your own load calculation. I suggest you spend $49 and get HVAC calc. Here is the link. The free on line calculators are simplified versions of load calculation software. I think they tend to be inaccurate.

You've gotten some great advice, but for new construction I would consider how $850 compares to the total cost of the HVAC. The 95% efficiency system has advantages in operating cost, and probably has other features (two stage, outdoor reset, etc.). Would you spend a few % more on a dishwasher or refrigerator to get a better version with more features, or will you use the standard version for everything you install? I like to choose better quality and features if the % of additional cost is low.

I would also get input from the HVAC contractor about how many units he/she has installed, get any information on the maintenance records. If the 95% unit is relatively uncommon in your area, or very new (no track record), or has complicated electronics that make repairs expensive, you may be satisfied with something simpler.

Bruce

I took the plunge on the higher efficiency unit because it has a 2 stage blower and with a utility rebate of $420 and a federal tax credit of $150 the cost was really not an issue in the grand scheme of things. The next question for me will be whether it is worth upgrading my ceiling insulation from standard R38(?) to R49. Waiting for a quote from the sub contractor.

There may be some online tools that will help you make the financial calculations for the insulation. It is very important for you to be sure the contractors are air sealing the house properly. Insulation gets much less effective if air is blowing through it and around it.

This is my 4th new construction home and the first where the contractor is sealing all the seams between framing lumber with silicone. I think sealing the big gaps with spray foam has been standard for a while but this is the first I have seen them seal the seams. In my last house I did it myself on nights and weekends. That plus spray foam insulation in all the walls made for a very tight house. This house will have FG in the walls and cellulose in the ceilings. I hate FG but it's what was in the budget.