Most folks find that its hard to keep even temps with a two story house and a single heat/AC system. There are ways to use vent dampers and multiple thermostats to zone a single system, but that can get complicated, and not every HVAC person can build a zoned single-unit system that works effectively.

I would push very hard for two units (up and down), unless you are sure the HVAC company really knows how to make it work with one system. Get references or ask to look through other houses.

Bruce

I find it strange the builder does not know what HVAC equipment will be supplied with the house.

I sounds like you will have one furnace and AC condenser set up with two zones. This is better than having one zone, but not as good as having a system for each floor. Two independent systems cost more than one. The HVAC contractor is looking to save money.

Zoning can work if it is done properly with the right equipment. The problem is most HVAC contractors are not good at zoning. I would also push for two systems. They will be smaller, maintain temperatures more consistently, and save some money on heating and cooling costs.

Thanks bcarlson78248 and mike_home. Still waiting for the report at this point. Do I have any defense in case they come back saying that one unit is sufficient? Should I hire my own HVAC or load calculator contractor or inspector to make sure the report is correct? I don't think average home inspector is qualified to do a HVAC load calculation.

Shawnmc,

The Manual-J load calculation won't tell you if you need one or two units, it will tell you the total heating and cooling load.

The number of units (1 or 2) is more about being able to control the upstairs separately from downstairs.

As was said, this can be done with dampers and zones, or it can be done with 2 HVAC units.

Since you will have two thermostats and one HVAC system, it appears your builder is doing this with zones.

The problem is that installers often aren't great with designing zone systems that work well.

I would push your builder for 2 units.

One furnace and AC can heat and cool a 2800 sq. foot house. For your climate I would estimate a 80K BTU furnace and 4 ton AC would be sufficient. The load calculation would confirm this.

What you really want is to hire an HVAC expert who can review how the zoning has been set up and whether you have the proper furnace and AC condenser to allow it to work well.

Mike_home,

Who would be the person I need to hire - you mentioned HVAC expert. Should I call around the home inspectors and see if they are qualified to check that? I searched for HVAC contractors and experts on google, didn't find many people in my area.

I doubt you are going to find a home inspector who has an HVAC background. The best option is to hire another HVAC contractor you trust. This may cause a controversy between contractors, so you have manage it.

What was on the contract you signed?

weedmeister,

That's the thing - the contract is silent on the number of HVAC units - it only says that it will have 2 (two) digital thermostats for climate control - one in the master bedroom (upstairs) and one in the family room.

But the sales rep said that it will be two units verbally, but it is not in writing.

This post was edited by Shawnmc on Sun, Jun 8, 14 at 20:42

"All the other houses in the subdivision ( Some of the houses are smaller and some larger) have two HVAC and furnace units each. "

If all the previously built houses have two HVAC units then why should yours be different? You should demand that your house be the same as the others.