I would suggest a mini split for the basement apartment. This would give the apartment temperature control and with no overhead duct work. The heating and cooling loads for a basement are low and at $0.11 per KWh it would be economical to operate. You will need at least two registers to cover the space.

For the second floor and attic a gas furnace and AC makes the most sense. If want to keep costs down you could do one furnace with zones for each floor. The furnace could be installed on the second floor in a utility closet ideally near the center of the house. The furnace should be variable speed, and the AC a 2-speed model. The duct work could run in the ceiling of the second floor so it can also service the attic.

Agree with Mike. Mini split for basement. One system for main floor. One system for 2nd and third floor with zoning controls.

IMO

Don't make the mistake of treating each level like a single story home when figuring required equipment and air delivery. Heat travel's up,take it into consideration. It's amazing how often we hear people asking why their 2nd story is always warmer year around.

Thanks for all the feedback.

Seems like the following would be a good starting design:

Basement. Either a dedicated mini split or electric baseboard. The basement will have a large open area with living, dining and kitchen, and then a bathroom and two bedrooms directly off that open area. Will it be enough to have one indoor unit? Never having used a mini split I don't know if there's a concern getting each of the rooms properly heated. I'm also assuming that the mini split will soon pay for itself compared with electric baseboard, correct?

Main floor. Have a gas furnace in the basement utility room serving only the main floor. Run the ductwork in the basement and use a main trunk with a low profile so that it doesn't protrude much into the basement ceiling height.

Second floor and attic. Have a variable speed gas furnace (optionally also A/C) in a utility closet either in the second floor or attic to service these two floors. The ductwork would run between the second floor ceiling and the attic floor.

Any comments on the above? How would it compare in cost to install and performance compared with having hydronic heat for main floor, second floor and attic, running off a boiler in the basement utility room?

Thanks.

Hector

Based on what you’ve
described my approach would be quite different from the other suggestions
you’ve received here. I would not install electric baseboard heaters or a
mini-split in the basement, unless air-conditioning was absolutely essential for the basement.

Your electrical costs are
quite high relative to the cost of natural gas. So I would suggest a modern,
zoned, hydronic system with perhaps a combination of in-floor radiant and cast
iron radiators where you may want a quicker response than in-floor.

This would be a much more
efficient system that would be quieter, more comfortable, require less
maintenance, have a longer life cycle and add more to the resale value than
most other systems.

If you do want to go the HP
route you can still have the same hydronic system described above and hydronic cooling – no ducts, with
this HP system. You would install hydronic fan coils in those areas where you
would want both heating and cooling.

Study the Brochure &
Manual; watch the video.

http://www.nordicghp.com/product/nordic-products/air-source-heat-pumps/air-to-water/

You’re designing a large
home with a lot of conditioned space. Personally, I’d sooner be moving water
than air for reasons of efficiency, comfort, noise and draft.

Given that this home will be
such a tight envelope you will have to give some thought to either an HRV or an
ERV for proper fresh air exchange that will be essential.

Should you choose hydronic,
hire the
best, most experienced people designing and installing high tech
systems and controls – you’ll be
glad you did!

IMPO

SR

I like this alternative suggestion...weigh the cost difference against a mini split...plus finding an experienced dealer to install in floor radiant heat might be problematic...I find mini splits very quiet so I don't see that as an issue. Discuss this option with your GC...

IMO

The hydronic solution for the basement is a good alternative. But I think it would be significantly more installation cost. Efficiency is probably not a top priority given basements have low heating and cooling loads. The mini split would aid in dehumidifying if that is a concern. With the hydronic system you may need to add a dehumidifier which is another cost.

Hydronic is not likely to be a thrifty approach for the owner of a rental unit.

Seattle can be damp and gloomy for months on end. The renter of a basement probably would want to be able to warm up the place pronto. There's probably no cheaper (and/or more functional) approach than to consider one or two externally vented gas wall heaters, depending on the room configurations. If dampness down there is a problem, then I'd also have a dehumidifier installed and properly plumbed and set up so that it operates without human intervention.

the basement area will require a standalone system...basements below grade carry a small heating and cooling load...might need a dehumidifier as well...good suggestions have been presented to OP for consideration...will AC be needed?...I would want superior insulation qualities for basement...fresh air exchange as mentioned might be required...

IMO

The hydronic solution for
the basement is an excellent idea if this hydronic air-source HP system were to
be installed. First of all, the HP is essentially a geothermal HP without the
ground loop; commercial quality that even includes a desuperheater for domestic
hot water and an electronic expansion valve for greater
control and efficiency!

I would suggest properly
insulating the slab in the basement with 2 to 4-inches of blue Styrofoam
sheets, installing closely spaced in-floor radiant throughout the house for a
lower supply water temperature and hydronic fan coil units in the basement and
elsewhere where you want quick control of temperature, dehumidification or
air-conditioning. Hydronic fan coil units are designed with drip trays and in some cases
with condensate pumps for the removal of condensate (water) in air-conditioning mode.

This system configuration
does not require a gas line, chimney, side vent or much annual maintenance. I
would install buffer tanks for both domestic hot water and for the radiant
heating and cooling for energy efficiency and to prevent short cycling when
only 1-zone is calling for heat or cooling.

This is a big house. Even
with gas forced air they will still require large electrically powered fan coils
to distribute the air. With in-floor radiant they only have to heat from the
floor till about 6-feet off the floor. Who cares what happens above that
height - remember, this is radiant! Forced air requires that you heat the entire volume of air within the envelope – a completely different
animal!

Haven’t even discussed the
possibility of using chilled beams for air-conditioning that’s possible with
this system. Heating without ducts, A/C without a fan coil – imagine that!

Think Water!

http://www.multiaqua.com/index.php/water-fan-coils/mhww-3-hi-wall-120v#mhww-3-installation-operation-manual

http://www.multiaqua.com/index.php/water-fan-coils/cffwa-universal-2p

IMPO

SR

fsq, I'm going to guess that not too many people buy heat pumps of any kind as a primary heating source when natural gas is available.

Is your experience different other than where electricity is very cheap?

In response to your question Snidely,all electric can have other advantages that tip the scales despite difference in cost. I've been involved with residential rental and commercial office properties over the years. It really causes alot of comotion when someone say's they smell gas. Evacuate apartment or office building then call gas supplier who turn's meter off and will not restore service until plumbers have examined intire system. i long ago lost count of calls I recieved when several people smelled gas,,,,,,,,,,,,,,,,,,,,,,,,,,,,although there was no gas service to building. Point being people's imagination can cost more than difference in energy costs,not to mention the hassel.

Practices must differ from region to region, klem, because in my area, if gas is available, heat pumps aren't used. (That's from an HVAC contractor I ran into a few months ago). Gas is available in all but the most remote or isolated areas. Even in all electric areas, people seem to prefer to use propane. That could be regional too.

I can't begin to imagine how expensive electric heat (of any kind) would be if used to heat a commercial property.

First Half...

“fsq, I'm going to guess
that not too many people buy heat pumps of any kind as a primary heating source
when natural gas is available.

Is your experience different
other than where electricity is very cheap?”

You always have to ‘run the
numbers’ and calculate the true cost
per kW of heat or cooling delivered,
based on a fair comparison of total energy
cost and efficiency of the equipment
being proposed, including the cost of electricity even if you are using gas.
Whatever the sources of energy, they must all be converted to a common
denominator for the sake of comparison, usually either kW or BTU. Real cost of
DHW should also be considered.

People have different
motivations for installing whatever they choose. It may not always be based on
the cost of energy. Subsidies can play a big part as well as does dual rate
electrical metering based on outdoor temperature, as is the case in some
jurisdictions.

Some people just won’t have
gas; they’re afraid of it. Others will not have oil, they’re afraid of a spill
or CO gas. Some people just want to ‘Go Green’ so it’s geothermal no matter
what.

Life cycle and installation costs
also have to be calculated and considered. In the house mentioned in this
thread for example, gas forced air would likely mean installing 2-gas forced
air furnaces, 2-air-conditioning condensers, 2-gas lines, 2-chimney liners or
side vents, full ductwork, forced air zoning and controls – all very expensive.

The savings of not having to
install 2-gas forced air systems can go along way to installing 1-hydronic system
that is properly designed, integrated and installed, not to mention not having
the annual maintenance cost of 2-gas systems.

Second Half...

The single hydronic
air-source heat pump system I proposed may yet be more expensive to install but
properly installed would over its life cycle be less expensive to operate,
would likely require no annual maintenance contract what-so-ever as well as
offering greater comfort and convenience through more precise zoning and
controls.

For a variety of reasons,
practices do seem to vary from region to region. Large commercial projects would
choose gas heating.

This concept for a hydronic
air-source heat pump represents my own personal opinion of what I would likely
install for this geographic location if not geothermal, just another voice in
the forest, that’s all. In the end, where residential systems are concerned,
everyone does what they perceive is best for them, whatever the reasons.
Perhaps they’re always right – for themselves.

IMPO

SR

Leaving aside the owner's part of the house, the topic is a small basement apartment to rent. I think you're trying to upsell the solution beyond reason.

A simple heat system, maybe even electric baseboards if they wish to avoid gas, is likely all that's needed. Not cheap to run but cheap to purchase and install. Maybe even a PTAC if the owner thinks cooling would be needed, though I can't imagine that for a basement in Seattle.