tracey

you have been offered typical cheap low end builder grade HVAC. If this was my home and I expected to live in it for the forseeable future, I would want the following.

downstairs

80% two stg VS gas furnace paired with matching 15 SEER heat pump.

upstairs

15 SEER HP with matching var speed air handler and staged backup heat heat strips.

IMO
Good Luck!

Thank you for the information and suggestions. Any idea how much more this roughly adds, above what the builder would install?

Thanks

no idea but you can bet your bottom dollar this is a profit center for most builders to line their pocket. if builder is reliable and above board, he should charge only his cost difference plus 10%.

IMO

13 SEER is the lowest SEER you can buy at this time. The price ranges between 13 and 15/16 SEER heat pumps just for the equipment around $1000 per unit. Price difference between fixed speed and variable speed air handlers or furnaces is about $750 per unit. It also depends on the brand of product you choose, but most of the brands 15 SEER is single stage compressors 16 SEER is two stage compressor. The price diffrence between 15 and 16 SEER is just few hundred bucks between the units, but if you are going to spend money get the better equipment. Just check specs for the brand you have in mind and get the unit with two stage comressor is stronger and more efficient that single comressor. And make sure if you get heat pump installed, have the installer put in outdoor sensor. When the temperature go lower than 20 degrees the sensor will shot off heat pump and start using indoor unit (furnace or air handler). At low temperatures heat pump freezes up and starts loosing efficiency. I am not so sure about you local temperature. I am in Washigton state and here it only happens maybe one week out of the year. The rest of the year on avrage heat pump will save 30-50% on energy bill depending on how you operate it. Heat pumps are more efficient if you hold the same temperature.

Here is a link that might be useful: Brothers Heating Website

Make sure they run properly designed metal ducts from the furnace/air handler(s) all the way to the diffusers (registers). Only the tail (the last couple of feet) should be flex. Metal ducts are expensive and require skilled craftsmen to install. They are significantly superior to flex duct.

Sub par HVAC systems and installations are all too common in new construction. They cost the home owner thousands and thousands of dollars in unnecessary operating costs over the years and rarely perform well.

Your best defense is to get the HVAC stated as an allowance in the contract with the right to approve the mechanical sub contractor. Then go shopping for a highly regarded HVAC sub who will do it right.

Expect to spend quite a bit more to have it done right with really good right sized equipment. Our allowance was $7,000. We ended up spending $15,000. We did not use the builder's usual HVAC sub that bid the $7,000 installation.

good point by creek side

ductwork is often overlooked and for new construction is usually undersized. ductwork has to be sized and designed correctly to the new HVAC. Metal trunk lines are preferred with flex runs acceptable. I would also recommend R8 insulation even for moderate climate of NC.

IMO

The better you seal and insulate the house and the ducts now will determine how sealed your wallet is every month. It is a WHOLE lot cheaper and easier to do these things now. I have spent OVER 40 hours sealing and fixing air leaks in the house and the leaky ducts and reworking my return system and at the time of build this would have taken less than 16 hours.

Thanks, guys. I've saved all your hints to study so we'll be more informed when we choose! I'll probably be back with more questions.....

I appreciate your time!
Tracey

Tracey - some points of reference for out local climate/economy

Nobody uses anything but flex duct at R8(code in attic and used elsewhere for simplicity). Our original HVAC budget was $13 and we spent $20. One contractor was $30 for metal ducts. Original was Seer 13 with no frills. We got Seer 15/16 Heat pump with gas backup down/electric up. Variable speed. 2 stage. Zoning. Total of 7 tons - 4 down, 3 up

Your specs are typical in that they are not very informative. They don't give size - usually what they'll do is say that they can maintain 20 degrees cooler than outside and ?? degrees warmer.

If you have the $$, seer 15 is generally worth it. I think dual fuel (ie gas and HP) is worth it. Variable speed and 2 stage are more comfort items - worth it if they are worth it to you (the other 2 are worth it in $$ saved).

If you have the land and the $$, geothermal is worth considering. To throws numbers around, I suspect we would have spent $40 for geo - down to $27 after tax credit. If you have land, the geo should be less - perhaps down to $20 after tax credit. You can then not have gas, longer life of Pumps, quieter operation, no external pieces and of course energy savings. Geothermal is the one of the few options for tax credits on new construction. In my situation, the money saved was not worth it in just $$$.

Lastly - there are a few items for our climate worth mentioning (forgive me if I have done this before). R-40 in the attic cost me $200 and reportedly saves $50 a year (code is r-30). Radiant barrier in the attic gave similar numbers. Energy star certification cost me $850 (or so) but saves me 5% on gas and electricity for life (Progress Energy and PSNC) - payback about 8 years. The extra insulating they do with energy star (cost hard to figure) all makes a ton of sense - mostly using foam around windows and doors - which I think cost $200. They also install backing behind tubs/soffits/on attic walls - that is hard to figure cost of since it went to the framers

Variable Speed is more of a necessity to me. It does a much better job of removing humidity in summer than a fixed speed blower. Otherwise, it should be quieter most of the time.

Insist on metal trunk (main) ducts. Flex duct is crap for trunks, and its usually installed like crap.

If your HVAC contractor wants to install flex duct everywhere, look for a different contractor who will install metal ducts. They are out there. You just have to look.

Google these forums for all the problems people have with "spider" ducts. They use flex for that.

creek side - I think everyone agrees that metal trunk ducts are better. What I have seen on every house in this area is a metal plenum with flex to a distribution box. The distribution box is metal with flex coming out of it. I assume that this is a "spider" style. I've never had a problem personally or known anyone but I've certainly read about many problems. The issue for me is that it was $10k more to do metal ducts. So I could have done it but I couldn't justify that kind of money. Maybe that number was grossly overstated but that was my option. The main benefit seemed to be less dust trapping.

As someone with a physics background - I would think that as long as the flow is good - what is the problem with flex duct? I realize that all the turns (and particularly kinks) will decrease the flow but if the end result flows fine - why pay an extra $2k or $10k. Does anyone really worry about longevity? Metal lasts a long time but plastic is not really a problem either and it doesn't rust....

David cary - For anyone to suggest a spider style setup is ok is NUTSSS. I am NCI certified and do static pressure test all day long. I bet that most spider duct install static Numbers are off the charts and not serving the homeowner very well. shure it may cool and heat the house but at what static? I ran into a 1/2 dozen spider systems this year and tested crazy static #. If a spider install is the only way due to space then super size the flex.

So I have high static #'s. What would be the downside of that. I would expect noise and resulting inefficiency of the blower. Perhaps extra stress on the blower?

So what I have is a very quiet system so my gut tells me the static pressure is probably not that high. Now I counted up the vents and looked at sizes and they are not exactly supersized. I'm sure that it matters that I have a variable speed blower and rarely see high speed.

Now I do experience some noise in the master bedroom zone during a/c season. The Infinity should be cutting flow due to pressure (right?) in this situation. The noise, interestingly enough, is the vent adjusting vanes rattling a bit due to high flow. This noise would actually get worse with better flow I suspect (unless it was pressure dependent but I am pretty sure it is flow dependent).

I am definitely not trying to disagree here - that would be foolish. I am trying to understand the downside from a practical standpoint. I know I am not the only person satisfied with a flexduct system. We all know there is the best way of doing things and there is the way that gets you by for a lot less money....

In my mind - it seems like a variable speed blower really minimizes the need for perfect ducts. An inappropriate band-aid perhaps but I can't complain.

If I would do it again, I'd put a return in all the bedrooms (I might still do it). That is where I'd put my money. The amount of airflow under the doors is a bit much for my zoned upstairs system since it is usually just 1/2 calling at one time (master or other).