HVAC system in new house

[JCA]

We're currently building a 2700 sq.ft.+/- house in NC. Met with HVAC contractor today. He is a friend of mine, grew up with my dad, and I've worked behind him several times so I trust his work. However I would still like to get knowledgeable opinions about it. For the first floor(1792 sq.ft.) he recommends a 3-ton unit(heat pump with gas back-up). For the upstairs( 800sq.ft. heated) he recommends a 1.5 ton heat pump. He is going to do a heat loss thingy this week and will build the duct work unlike amny who use flex only. Will have outdoor thermostat for furnace and variable speed fans. He says all units are about the same but has had very good success with RUUD. Does this sound about right?

[Sparks]

The fact that he does a heat loss/ gain calculation and uses outdoor thermostats tells me he's probably a knowledgeable contractor. You've worked with him before so trust his judgement, he sounds competent. Rudd is a high quality company from what I've seen.

[rabadger]

Sounds like you found a winner. The load calculations are very important.
Just ask if they will be room-by-room. (It's the room-by-room calculations that are used to size the duct.)

You are on the right track! NO FLEX DUCT :D

He is using a fosil fuel kit. Thats a good thing. The thermostat outside shuts down the heat pump as starts the furnace. This is done because in some areas of the country heat pumps do not get along with cold weather.

GOOD LUCK :wink:

[JCA]

Richard, he will do load by room sizes, but he will use some flex from the main to the vents. Is there a major problem with this method?

[rabadger]

Yes.

[JCA]

FUDGE :(

[danh]

Because things like orientation, glazing distribution & local weather have such a huge effect on load calcs, it is impossible for us to give you an estimate of sizing suitability without doing a full Manual J calc. or similar on your home.

As for your contractor, him doing a load calc is not an absolute indicator of a good contractor. I've seen a number of guys that adjust their numbers until they get the unit size they want, and then only use the print-outs to get the duct distribution.

I'd rather have a contractor tell me that he didn't know what size I'd need until he did a load calc.

[Sparks]

Good point danh, I missed the part where unit size was recommended BEFORE load calc. was to be performed. I'll second your opinion. Good catch.

[rabadger]

If flex duct is not installed properly, it creates to much resistance to air flow. I is hardly ever used correctly. Most of the time when you see fles duct it is strung all over the place, not pulled tight and if hung sagging.