HVAC Design guru's - Need Advice

[Rusted Nut]

Hello;

We will be building a new daylight/walkout basement home in northern Arizona next year. Winter temps into the 20's at night, 50's during the day. Summer lows 50's/60's at night, daytime highs 80 - 90. We have natural gas service to the property. R21 walls, R 38 attic. The basement will be storage and guest bedrooms, and an office. Office will be used regularly, bedrooms on occasion. Main floor is fairly open floor plan with gas fireplace with fan in living room. Yes, I'll have a good sized shop; but most likely not heated or cooled.

Leaning towards a gas heat pump type system; similar to this very informative thread:

Looking for a home heat pump system. I need advice.

I'm looking at buying a heat pump for my house. I've had five contractors here, and they each recommend something different. One guy recommended a single-stage system because of 1960s ducts in the slab can't be altered. He says that the static air pressure will be a problem otherwise. He...

www.garagejournal.com

Questions:

• Can we install dampers that can shut off heat/cooling to the basement rooms with newer heat pump systems?
• Strongly thinking of installing a electric wall heater in the office, to just heat that in the mornings. Possibly master bath as well to keep from running the main system. Thoughts?
• Usually one would not insulate a ceiling above a conditioned basement, but what about a ceiling in a basement that won't be conditioned most of the time? Counter productive? Bedrooms will at rear of house, facing SW; storage will be in front up against 8' concrete wall w/R10 furring wall.
• Any other thoughts? Both upfront costs and operational cost are equally important.

Thanks!

 

[Jackfre]

As you are just planning the build I think you would be best served by orienting the property for solar. Then you can go all electric which I believe will pay out best for you. You have to run the numbers on gas/elec HP, but with the solar you are making your own. With the gas, you are riding the nationwide increases in cost with no protection from them. HP water heater or gas tankless, As to going elec on BR and MBR that pretty much depends upon your floor plan. I would insulate the floor just for sound proofing purposes.

 

[jlv03]

Zone as much as you can, either via separate systems or zone dampers.

 

[fitter30]

Before picking a system need heating and cooling degree days. Insulation, windows,doors, house wrap and roof type / underlayment. Pay for it once or pay every month.

 

[JunkBonds]

You won't need aux heat so nix the gas burner furnace

 

[danski0224]

Questions:

First, you need a load calculation and duct design.

• Can we install dampers that can shut off heat/cooling to the basement rooms with newer heat pump systems?

Zoning makes zero sense for forced air heating or cooling unless your equipment can modulate capacity and airflow. Otherwise, you are still operating the equipment that makes X btu of heat or cooling, but are using x-y and dumping the rest somewhere in a dump zone.

If the ductwork and fittings are designed properly, there will not be airflow issues. So, this will rule out the typical residential flex octopus monster.

Typically, zoning is used as a crutch to "fix" ****** ductwork.

Zoning radiant? Yes, by all means.

Or you have a commercial type forced system with a medium pressure main trunk and separate VAV boxes with reheat coils and thermostats for your "zones".

• Strongly thinking of installing a electric wall heater in the office, to just heat that in the mornings. Possibly master bath as well to keep from running the main system. Thoughts?

Depends on your cost of electricity.

• Usually one would not insulate a ceiling above a conditioned basement, but what about a ceiling in a basement that won't be conditioned most of the time? Counter productive? Bedrooms will at rear of house, facing SW; storage will be in front up against 8' concrete wall w/R10 furring wall.

The basement is either "inside" or "outside", not both. It needs to be treated as the rest of the house, but it is difficult/impossible to heat/cool a basement and maintain a temperature if it is tied to the HVAC system that feeds the rest of the house. I would strongly suggest a separate system for the basement, and that can likely get away with resistive backup heat (depending obviously on the size of the space).

Basement would be a good place for floor heat.

• Any other thoughts? Both upfront costs and operational cost are equally important.

I would put the gas furnace in as an emergency backup if you are installing conventional ductwork.

High end equipment costs high end money, no getting around it.

I would put the foam on the roof like a commercial building and make the attic conditioned space. The shingle manufacturers have details on how to do this and incorporate a vented space for the shingles. It does create detailing issues for the edge of the roof, but it eliminates the out for shingle warranties due to spray foam on the roof deck and covering the foam with drywall or a fire retardant coating.

Air sealing is key.

 

[Rusted Nut]

I'll start getting load calc's going. Lot's to think about. Thank you all for taking the time to respond. Great advise, most appreciated!