Thank you for your response Tigerdunes. I will definitely check with the bidder on the third party evaporator coil. I specified matched systems having read your prior posts to others extensively, but didn't catch that this evaporator coil wasn't a matching Trane. Thanks. The boiler was sufficient in heating the entire 1200 square feet main floor living space with AND without all the radiators in place. I don't recall the size at the moment, but will check. The HVAC people were all pleased with its size when they looked at it. Because the house is without electric and water service as yet, we are not totally sure the boiler is still in working order. It was not fire damaged, but water from the fire fighters and heat from the fire might have caused some unknown problems, which was another reason to hedge the bet by adding a gas furnace. The second reason for considering a gas furnace, not just A/C is that a realtor who knows the house and its value, - which is considerable for a small house, given its location and craftsman, cedar shingled cottage charm - suggests that some buyers don't like radiator systems, and feels the addition of an alternate heat system and the addition of A/C will be worth it, which is another reason I got the bid for it. The third reason for considering a gas furnace is code compliance, and the cost to do so. The cost of adding hydronic units to the sunroom, pantry, dining room and bath areas to meet code are unnecessary if I install the gas furnace. Anyone wanting to use the radiator system only for heat would have to add these units, or live without them as I did, but code is met with the addition of a furnace. No furnace, and I have to add radiators in the areas mentioned above and detailed below. I agree that a heat pump would be the way to go if we knew for sure that the radiator system was going to be the primary source of heat as it was when I lived in the house. New owners might opt for a forced air system. My question on this is, can a gas furnace be added into the system as cost effectively later as it can be added now with the A/C going in. The new heating system, if installed, l would heat/coo the 1200 sq ft main floor with its 9 ft ceilings, with two registers in the open 950 sq ft unfinished basement. The basement stays cool in summer and warm in winter without additional heating and cooling. The attic space, if developed later, will be heated and cooled with an in-wall, Mitsubishi type system. Trying to run ducts and vents is a problem, which is why we don't have the new proposed system sited in the attic. It would make the attic fairly unusable in a future development as a master suite and sitting room. The ducting layout using the in the basement location has worked well, and the location of cold air returns well placed and spaced. So the attic will not be heated or cooled with this system. In the past, with the boiler, the heat loss from the main floor was enough to keep the attic above freezing, but does not warm it significantly. The attic has 4 large double window sets, 3 large Velux skylights and a 4.0 french door set, and the roof is black, so it stays warm enough on sunny days, and is well ventilated in summer.. The attic floor will be re-insulated at this time, but not the walls or ceiling. The new insulation in the attic floor will be far better than the old, and as I said, the new windows throughout, from basement to attic are a vast improvement in energy efficiency over what the boiler used to have to handle. The 950 sq ft basement is unheated at present, though I believe two registers will be added to this space with the new furnace The basement stays comfortable in winter when the boiler is in operation simply from the hot water pipes to the radiators and hot water heater and warmth of the up stairs. It is is open space, unfinished and only used for laundry and workshop space/tool storage. The dining room radiator was removed from under a south facing bump out window. That window was removed and replaced by an exterior double french door when a new deck was added at the time of the new boiler. The heat loss to this room was noticeable but not enough to be a problem for me, though it would be for others, and it is for code. Each room has to have a heat source, so I either have to put in a register or add a radiator. The bathroom is only 6x7 and is now warmed by the heat/fan which is not sufficient for code. I have a not yet installed hydronic towel bar that gives off 1500 BTU, enough to handle the bath and the small hall adjoining the dining room, bath, bedroom and parlor. If I do the gas furnace, this is unnecessary. At same time the new boiler was installed, a kitchen was installed in a 11x12 ft space that only had a sink and refrigerator with a radiator. An adjoining but separate 6x8 pantry at the south end of the kitchen had a stove and a cabinet. The pantry is also an access corridor to the basement stairs. So in installing a kitchen, I removed the radiator and replaced it with a toe kick radiator under the sink base the fully fitted kitchen. Base and upper cabinets were added to the pantry on the load bearing exterior wall that separated the pantry from the screen 8x8 screened back porch at the other half of the kitchen south wall. The fire that started at the electric service connection into the house was located on the east wall between the kitchen and screen porch, so this area and the attic above it were severely impacted by the fire. In rebuilding this area, the screen porch got a solid foundation, was mostly opened to the kitchen, and serves as a sunroom breakfast area. It is,fully windowed from ceiling to 36 inches above the floor with a door that opens to the deck. The load bearing wall separating the sunroom from the pantry still exists, but the pantry is now open to the kitchen rather than walled off with a doorway. The kitchen toe kick puts out 5,600 BTU and has to handle the kitchen sunroom and pantry area now. If I do not add a furnace, code will require me to heat the sunroom and pantry areas, which I would do with toe kick units under the pantry base cabinets - one venting into the sunroom through the wall and one venting into the pantry. If I add a furnace, this will not be required, we will simply use those areas for the forced air registers. If I do not add a furnace I will have to provide hydronic heat sources for both areas. So, to answer your question 4, the only addition to the heat load that the boiler has covered adequately (1200 sp ft) is the 8x8 fully weatherized and insulated sunroom. If I go with a gas furnace we will add the register(s) for the unfinished basement. I don't know if code requires the basement to be covered. I do know the non living space attic does not need to be covered. Sorry for all the detail, but I find that sooner or later the information is needed, so I am trying to give it all upfront.

Oh my! I apologize for creating a stir. My intention was not to bash those that live in larger than average size homes. I think that we can all agree that some people just dont need as much space as others but itÂs not right for those people to discount other peopleÂs lifestyles. However living in a larger, less efficient home definitely has a negative impact on our environment and the new building trend is definitely leaning towards sustainability. This should be acknowledged and accepted by all. The purpose of the posting was to see whether or not 1,100 sq ft for a two bedroom unit is acceptable for most people. I think more accurately, my posting should be asking if 750 sq ft for a one bedroom loft is acceptable, as well as 350 sq ft for a studio. And yes, I realize that in Honolulu everything is much smaller. That was another purpose of my posting, to see if other parts of the mainland US are starting to shift towards smaller more efficient home design, something that Honolulu has been doing since the beginning of time. Condos and single family homes did increase in size since 1940. For example, a two bedroom condo or duplex in 1940 had an average size of about 500 sq ft. Today, the average size is about 850 sq ft. Single family homes increased from an average 3 bedroom home of about 1000 sq ft in 1940 to about 1700 sq ft today. So the increase is not quite as dramatic as that in the US mainland. We are seeing a slight shift in home size in todayÂs new buildings but I donÂt think itÂs as dramatic from what IÂve seen in the US mainland. But thatÂs probably because we didnÂt experience a "size run-up" like the mainland did. And for the record, I wanted to copy and paste a follow up I created on another category on the GardenWeb forums about a week ago. It describes how the 3 levels were actually split up to accommodate multi-person living. You will see that my design was not intended for ONE person , ONE couple, or ONE family to live on all three floors. The design is such that the home can be shared by extended family (for example grandma on the fourth floor, children on the second and third). But they have their own kitchens, bathroom and living area. I completely agree that a 1,100 sq ft home spread across three floors makes no sense. But if you NEVER had to access the spiral stair case at all, would it still be an issue? Hopefully the follow up I created below will lead to clarification. Original post follows (sorry, itÂs quite long) The units are being built and sold OR rented (I may end up renting the property instead of selling) as "hybrids". Meaning that the unit originally built as a 2 bedroom, 2 1/2 bath can be converted into a one bedroom loft AND separate studio with completely separate living spaces. Let me explain how this works and then maybe the elevator concept will make more sense. Imagine 5 units in a single row configuration, just like a typical townhouse layout in San Francisco for example. Each unit is tall and skinny (3 stories of living space, garage at basement) and butt up to each other. From the outside you will see units 1, 2, 3, 4, 5, in a row from left to right with shared common walls. Each unit has an identical floor plan that consists of: First floor is a parking garage Second floor consists of a kitchen, living area and powder room Third floor consists of a one bedroom loft (you can see down to the living room below) and full bath. Fourth floor consists of a one bedroom, full bath and wet bar (essentially a full kitchen without a full size range). There are two staircases  one staircase is an average size if maybe on the smaller size spiral staircase that runs from the parking garage level to the top floor (fourth). There is access via the spiral staircase by door at the parking level, as well as a door at the second floor entry (kitchen and living) and another door at the fourth floor (one bedroom, full bath and wet bar). The spiral staircase, however, bypasses the third floor (it spirals past the third floor but does not allow access) and therefore does not allow entry to the third floor (one bedroom full bath loft). This is where the second SEPARATE staircase comes in which allows access from the kitchen/living area to the loft bedroom above (access from the second floor to the third floor). This second staircase is on the opposite side of the condo. If you wanted to get to the fourth floor from the living/kitchen area you would have to take the spiral staircase and bypass the second floor bedroom loft. The spiral staircase is essentially converted to a common area if the units were split up. If kept as a two bedroom condo, the spiral staircase is a private stairway much like any stairway in a house. The elevator would be of three-stop design. It would start at the parking level (first stop), then stop at the second floor (second stop) and the last stop would be at the fourth floor (third stop). Like the spiral staircase, the elevator would bypass the third floor altogether. Again, the third floor is ONLY accessible by the separate staircase (non-spiral) on the opposite side of the condo that is accessible from the living area (second floor). Confused yet? I apologize if you are. IÂm trying my best to outline my design via words. So the 4-story property can essentially be split into two separate living spaces  a one bedroom loft and studio. The elevator would allow easy access to the studio unit (if converted to two separate units) and I felt it was necessary. Who wants to walk up 4 stories to get into their unit? I figured that if the property was converted into two units, the resident of the studio would always use the elevator to access his/her unit, while the resident occupying the one bedroom loft would simply traverse the spiral staircase one floor to get to his/her unit. He/she living in the one bedroom loft could still use the elevator (all entries to each floor via elevator are keyed) in the case furniture, groceries or other large heavy items need to be transported. The elevator is large enough to fit a wheelchair and can fit most appliances and furniture. Large furniture may not fit. Reason for this design is that many people in Hawaii buy a home and rent out a portion of it to help cover the mortgage. Cost of living here is ridiculous, and housing is the biggest expense. Extended family living is also very popular here so the ability to separate one unit into two becomes very attractive. Keep in mind this place is being built in dense urban Honolulu, in downtown. The average one bedroom is about 600 sq ft, studio about 375 sq ft and 2 bedroom about 900 sq ft (we have to be much more efficient with space here). Without splitting the unit into two, the two bedroom is about 1,100 sq ft. If the property was split into a one bedroom and studio, the size would be 750 and 350 sq ft respectively, well within the acceptable size range for the area.

I use 12-15 years for AC and 20-25 years for furnace as standard expected lifetimes for planning purposes. They can last longer (or not as long). If you have temperature extremes it's good not to wait until the unit completely fails - because that's generally in a heat wave or -20 when everyone is having HVAC problems. That said, most things on a furnace can be easily replaced except the heat exchanger - and that should be inspected each year. Many things on an AC unit can be easily replaced until you get into rotted coils or a damaged compressor. Water heaters generally last 10-15 years here with the hard water. I don't try to see how many extra years I can get out of a water heater because I'd rather it not open up. Water heaters are not unlike brakes or tires on your car... you don't wait until they fail to replace them because the problems that can cause. If you have the money to replace the units and they are at the end of their expected life span, do it and avoid the hassle of an unplanned breakdown. I agree with Mike Home - if you have a PRV or a check valve on your water main, you are required to have an expansion tank. If you don't, then an expansion tank provides no benefit and will be one more thing to potentially leak.

"Crawlspaces are not in the conditioned space though." Crawl spaces, like attics, can be either "vented" or "unvented" and meet the requirements of the International Residential Code. Sealed, conditioned crawl spaces are indeed in the conditioned space (thermal and pressure boundary) of a home. "That's what the fuss is all about. Efficiency is great if it has a monetary gain. Of course if money is no object, then you're just doing it to impress strangers." While you're looking at this from an HVAC standpoint, Ray, there are a number of reasons to construct a conditioned crawl space in lieu of a conventional, vented crawl space. That's the building science part. Our company has been designing and building conditioned crawl spaces since 1999. We've found that there isn't a big savings in energy cost, but there are significant benefits gained by minimizing the potential for condensation on duct work and other surfaces, minimizing the potential for mold/mildew, improving the air quality in a home, and maintaining conditions which are less hospitable for termites and other insects. Think "big picture," Ray.