PennSilverTaco's "Perfect 5-Lug Regular Cab" Build, Aspergers, and General BS MegaThread!

My neighbor owns a company that designs HVAC systems for large mansions and commercial buildings, specifically the ductwork...

I was chatting with him yesterday, and it got me to thinking about something I've been meaning to post for a LONG time...

Dual-zone systems versus single systems in two-story homes over about 1,500 square feet!

 

I don't know if this varies by township, but in my area, I believe new construction homes are required to have two separate central A/C systems if they about like 3,000 square feet (it might be less than that). Generally, new homes around here have dual-zone (Separate systems, not one system with two or more zones) if they are above 2,700 square feet.

My parents' house is like 2,900 square feet not including the unfinished basement, which strangely has two vents (I've never seen vents in an unfinished basement before)...

My parents bought a brand new 2-story, 4-bedroom colonial in Montgomery County in 1990; This house was over 2,700 square feet and only had one central A/C unit matched up with a gas furnace. As is common in this area, the A/C was located on the side of the house and the furnace was in the basement (unfinished). My dad does not recall having any issues with hot and cold spots in that house, and remembers that the A/C always worked fine during the six years we lived there (About November 1990 to June or July of 1996). I had the opportunity to talk with the guy who bought the house from my parents in 1996 a couple years, when he was in his front yard when I happened to drive through the neighborhood...

He said that the original air-conditioner crapped out in about 1999, which is shocking to me because I still see those old Snyder General A/C units (see below) in operation to this day...



They are a bitch to work on according to technicians I've talked to, and certain specific parts are hard to come by, but I regard them as being well put together and very reliable. My old neighborhood in North Wales was built between 1989-1990, and 1993 or so, with the last houses being built in 1993-1994; All of the houses had Comfortmaker-branded Snyder General units, and as of 2019 some houses still had those units after three decades! At least one of the houses was extensively renovated inside and out with a large addition off the back; The house gutted and a dual-zone dual-fuel system was added, consisting of two Carrier Infinity Series heat pumps...

At least one of the houses (which my parents and visited as an open house maybe 8-10 years ago as an open house), retained the original single-zone system, but has a ductless mini-split heat pump installed in the master bedroom to compensate for what I'm guessing was a hot spot; This house, and the extensively renovated example with the dual Carrier units, were both the same floorplan/model as ours, the Dunhill. The development was built by the now-defunct David Cutler Group...

 

Like most older developments where many of the original HVAC systems fail within ten years of the houses being built, it is not uncommon to see at least half a dozen different brands, including the original builder-grade equipment; Some of the houses have cheap Goodman units, my old house has a 2006-2008ish Bryant that appears from the street to be a mid-grade Preferred Series, and many houses still retain the original Snyder General/Comfortmaker units that 26-27 years old at the very newest, as of 2020! Carrier is by far the most popular replacement brand in that neighborhood, followed closely by Trane...

I have not seen any Lennox or Rheem/Ruud units (they're probably there, but bushes and trees prevent me from seeing A/C units from the street in most cases), but Comfortmaker, Carrier, Bryant, Trane, and Goodman, plus the Mitsubishi Mr. Slim at the open house, makes six!

 

I have lived in ten different houses, in four different states, in my 31 years on this earth; Six of those my parents owned, two were rented, and two were owned by the government. I am not including the apartment my parents briefly rented in Montgomery County in the summer of 1990 while looking for a house...

Of those ten houses, six had central A/C; Of those six houses, five had gas forced air heat, one had oil forced air heat; Only one of those houses with A/C, the one with oil, was a rental. The houses with no A/C were all on West Coast; The ones in California (one owned by parents, and two owned by the Navy) all had electric heat. The one in Washington had gas forced air heat, and central air could have been easily added...

Of the six houses with central air, only two had dual-zone A/C, and they were built in 2007 and 2015-2016, respectively...

 

The first house we had with dual-zone A/C was an end unit townhouse, built in 2007; It was two stories, with three bedrooms, and was about 2,300 square feet not including the finished basement. With the finished basement, I'd like to say it was well over 2,600 square feet, but even though there were vents in the basement, being a basement it didn't really have much effect on cooling performance because it was underground and never got hot!

The house was built by Toll Brothers, and it was of typical tract home quality; I loved that house (not just because of the powerful A/C though), but there was a lot of corner-cutting...

The A/C was one area in which that house truly shined; By default, the 3-bedroom version of the Lyndon came with a single-zone system, and the 4-bedroom version came with two, including in the upgrade cost. Strangely, I saw one 4-bedroom model with only one A/C unit (This was probably built in the earliest stages of construction, in 2004-2006, and Toll learned from their mistake); On the flipside, our 3-bedroom was the only such Lyndon in the neighborhood with dual-zone. When my parents sold it, I convinced the realtor to mention in this in the MLS ad!

 

The rented house we lived in from 2005 to 2007 had an aging and relatively lackluster A/C unit matched up with an oil furnace; I believe it was a 1980s-1990s Goodman/Janitrol unit (the house was built in 1988, and it may have been original). The A/C worked great when it was working, but it had a nasty Freon leak and the owner refused to replace the unit; He put a metaphorical bandaid on it every year by having his HVAC guy come out and charge it in the spring, and a charge generally lasted the whole summer. The biggest issue with the A/C in that house, after the leak, was the typical unevenness that came with a single-zone system in a decent-sized 2-story home; You had to freeze out the downstairs to get the upstairs comfortable, which resulted in more wear-and-tear on the system, and a higher electric bill...

 

We went to look at the new house while it was being built in April or May 2007, and I noticed that the next door neighbor's Lyndon, a 4-bedroom model, had the dual-zone system; I told my parents they should get a second A/C, and my parents initially said no because they didn't want to spend the extra money...

However, they visited the decorated model Lyndon (also a 3-bedroom with the standard single-zone system) on a warm day and noticed that the upstairs was considerably hotter than the downstairs. They decided that spending the extra money (approximately six grand if I remember correctly) would be a wise investment, and did the new home HVAC equivalent of ordering a 1969 COPO Camaro with the 427...

The A/C in that house worked GREAT; My bedroom was above the garage, and it was consistently like a walk-in refrigerator even on the hottest days! It consisted of two Carrier 2-ton (24,000 BTU) 13 SEER A/C units and two Carrier 90% efficiency 40,000 BTU gas furnaces; The system was not without its issues, most notably the fact they installed the furnaces with the filters in the standard locations (incredibly difficult to access). They also used one condensate pump for two systems, and installed the furnaces so close together that adding a humidifier was practically impossible!

The upstairs unit blew a run capacitor in the summer of 2014 and also had to be recharged (due to being low on refrigerant) on the resulting service call, but in the nine years we lived there those were the only problems, and as of 2020 those units are still there!

 

The upstairs system in my current house does not work as good as the one in the townhouse primarily because of the haphazardly installed flex-duct in the attic; A tech who came out to diagnose the problem described my bedroom as being "The last stop for the SEPTA train"...

Having a TV, a PS4, and a MacBook running in my bedroom most of the time doesn't help! The furnace is located in the attic right above my bedroom, and my room gets incredibly hot when the furnace is running, forcing me to crack my window even when it's below freezing in order to sleep comfortably!

 

All of the houses in my neighborhood were built between 2015 and 2017 or so; All but two have dual-zone systems, and all have the same subpar builder-grade Goodman equipment; The aforementioned neighbor who owns the HVAC engineering firm plans on switching to geothermal heat pumps once the builder-installed systems die. One of my neighbors added a fifth bedroom above their garage a couple years after the house was built, and luckily the upstairs system was slightly oversized, so they didn't have to modify the system; However, since they were doing extensive work anyway, the owner had the flex-duct ripped out and replaced with a far superior metal duct system that really improved performance...

I have no idea why the two houses in my neighborhood were built with only one system, other than that the building code didn't require it because of their size; I think it was a dumb idea...

 

Every house is different, and there are many factors including the typical weather conditions in the building location that affect system performance; In my opinion, however, any 2-story house of maybe 1,500 square feet or more should have two separate systems or at least a zoning damper in the ducts to control airflow...

The biggest issue for me is that having two systems (or a multi-zoned single system) would allow one to raise the temperature on the downstairs system or turn it off completely during the summer while keeping the upstairs comfortable; In the summer, we keep the upstairs system at 68 and the downstairs at 72-75 when we are sleeping...

There is a new house in Doylestown, built maybe two years ago on the site of an old house they tore down; It is not particularly big (probably less than 3,000 square feet not including the basement). The house is on a tiny lot and has only a 1-car garage, but it is three stories and very tall; Instead of adding two medium-sized systems,or one large and one small like I've seen in the past, the builder went with three small A/C units and presumably three gas furnaces (the units are definitely not heat pumps). I probably would have done the same thing to be honest!

My neighbor in the Toll Brothers neighbor specified the optional third floor loft, which by default gave his house a standard second unit for the third floor; There is one large unit for the rest of the house (first floor, second floor, basement) and the second unit for the third floor. A few original buyers of that model (the Claymont) opted to not get the third the floor, but bought a second system for the 2nd floor...

There were three different "lines" of homes available in that neighborhood, each consisting of three homes; There were the townhomes that looked more like traditional homes (which we had), there were the city-style townhomes with the "drive-under" basement garages, and there were the condos (occupants owned the house but not the land) that were built either with drive-under garages or detached 1-car garages behind the house depending on where in the neighborhood they were built...

My neighbor with the third floor had a Claymont, the second-largest house in that "line/series" and the only one available with a third floor; The Claymont could be built as an end unit or an inner unit (inner unit Claymonts were far more common). The Claymont was not available with a 2-car garage, but could be customized with features like the aforementioned 3rd floor loft, a 4th bedroom in place of the 2-story family room, and dual-zone A/C. The biggest model available in the whole neighborhood (not just its lineup) was the Lyndon (which we had); The Lyndon was only available as an end unit. The Lyndon could be built with a 1-car car garage, but I only saw three 1-car garage Lyndons in the whole neighborhood, including the decorated model built in 2004; I never saw a single 1-car garage/4-bedroom Lyndon, and our house of course had a 2-car garage, which was so popular that Toll Brothers automatically built the plan with a 2-car garage unless the buyer requested otherwise. The Lyndon could ordered with a 4th bedroom, but at the expense of losing the vaulted ceiling in the living room and the expansive 2-story foyer, and also resulting in an exterior that didn't look as good as the 3-bedroom version; My parents opted for the 3-bedroom. A kitchen bumpout and a "garden window" were the only significant upgrades available on the second floor; My parents got the larger kitchen, but it was too late to get the "garden window" by the time they went to the Toll Brothers design center to select their options.

The smallest floorplan in our series was the Birkdale, and also the least customizable; The Birkdale was only available as a middle unit, only available with three bedrooms, and not available with a 2-car garage. I'm pretty sure it was technically possible to order a dual-zone system, but I did not see a single Birkdale with two A/C units. Subsequent conversations with people who live my neighborhood when making DoorDash deliveries have revealed that people think the single-zone systems suck...

 

There are exceptions to my "Two-story houses over 2,000 square feet should have two A/C units" rule; My best friend Doug's parents own a huge 2-story, 4-bedroom home in the middle of nowhere; The home was built in 1987 (they bought it in 1995) and has at least 2,700 square feet of living space not including the finished basement. Being in the middle of nowhere, there was no access to public natural gas, and propane wasn't popular at the time; If I were building that house in 1987, I would have gone with oil heat, but for whatever reason all of the independently-built houses on that isolated cul-de-sac had heat pumps.

The house originally had a builder-grade Trane heat pump and an Trane air handler with electric backup heat. The house also has electric baseboard heaters in the finished basement to make up for the lackluster performance of the heat pump; The original Trane heat pump failed in 1999, but the air handler still worked. Since R-22 Freon was still in regular use back then, there was no need to replace the entire system. I believe that the original unit was a Trane XE 800 (the "800" designating it as a 8 SEER); The replacement unit was a virtually identical Trane XE1000 (the "1000" meaning 10 SEER). The replacement unit had a manufacture date sometime in late 1998, but it was installed in the summer of 1999 (meaning it sat in a warehouse somewhere until the installer ordered it). The Trane XE1000's compressor failed in April 2010, and though the company that installed it was willing to replace the compressor, this was almost as much as the original cost of the unit back in 1999! Doug's parents pretty much put me in charge of picking out their new HVAC system because they didn't know anything about HVAC; I picked out a 16 SEER Bryant Evolution System with a 2-stage scroll compressor, and a variable-speed air handler with 20kw electric backup heat, and that's what they bought; The total installed cost came to well over eight grand, but with all of the government rebates and tax incentives (including a manufacturer rebate and a rebate from PECO), it was substantially less. Doug's parents are both successful attorneys, so paying cash for the new system was not an issue.

I even documented the removal of the old Trane and the installation of the Bryant, and made a YouTube video. I think I picked the right unit, because in just under a month it will have been exactly ten years since the Bryant was installed (June 3rd, 2010) and as far as I know the unit has never required any unscheduled service!

 

The Trane died maybe four months after I really started hanging out at Doug's house, so I never had the opportunity to get a feel for the unit's cooling performance; However, I was upstairs on a hot day after the Bryant was installed. Not only was it pretty comfortable upstairs for a house with only a single system, but I put my hand over the air vent in Doug's bedroom and was surprised at how powerful the airflow was. I have no doubt that my decision to choose the 2-stage/variable speed system played a role in this, but I've talked to owners of other large houses with one 2-stage/variable-speed system and they say it doesn't make much of difference over the single-stage system it replaced...

Doug's parents' house is obviously well-built, likely has 2x6 exterior wall framing, and probably has more insulation than the minimum required by local building codes; The house is easily over 3,000 square feet if the space of the finished basement is included! But, Doug's house is the exception rather than the rule...

 

Approximately 8 to 10 years ago, my parents went out looking at open houses on a particularly steamy Sunday; There was this one huge colonial that I absolutely loved, and it only had one system! The house had been built in about 1990 or so, and had the original system, a 5-ton Bryant straight-cool A/C unit matched up with an oil furnace. This house was utterly huge (well over 3,000 square feet; I don't remember if it had a finished basement, but it did have a bonus room/fifth bedroom on the second floor, and I can remember that the single 5-ton Bryant was keeping the house consistently cool. Even in the huge 2nd floor bonus room, the air coming out of the vents was really powerful! Another exception to the rule; This house was not your typical tract home from a company like Toll Brothers. I believe that the good performance of a single-zone system in such a large house was the result of two things; A carefully engineered system of ducts, and really good insulation. I would most certainly not build that same house today with only one system, but as far single-zone systems went, that one was pretty good!

 

Another good example would be the 2-story home of my friend's parents; They are the original owners of the house, and they had it built from the ground up in 1978 or so. They wanted to save money and did not have central air installed at the time of construction, but they knew they would want to add it later and had the ductwork installed. The house has a hot water baseboard heating system, with an oil boiler in the basement; My friend's parents installed central air sometime in the late 1980s, and as of about five years ago (I don't go to his house much) the house still had that original Lennox installed in 1987 or so! The house is not small, but even with subsequent additions it is not that big either (no more than 3,000 square feet if I had to guess). The indoor unit for the central air (separate from the boiler and with no heat of its own) is installed in the attic; Since cold air falls, this is a perfect setup, and the house does just fine with only one system!

 

My best friend's parents' old house (sold in 2012) was built in 1969 and did not have central air; They bought the house in 1989 or so and made due with window units until 2008, when they installed central air on the 2nd floor only...

The house had baseboard heat, and in 2012 when they sold the place, it had the original American Standard gas boiler that functioned perfectly! There was a HUGE window unit installed in a cutout in the rear wall of the family room, and this did an excellent job of keeping the first floor comfortable; They saw no point in spending double money for a second system on the first floor. The unit for the 2nd floor was a basic Carrier 13 SEER unit with the air handler in the attic; I live within walking distance of my friend's old house, and this Carrier is still there, along with the big window unit on the first floor.

 

One of the most egregious examples of a poorly designed/undersized HVAC system is my aunt and uncle's old house in Northern Virginia; I've mentioned this system before...

The house is well over 3,000 square feet not including the finished basement (even though Zillow lists it at 2,900 square feet); The house had a single 5-ton (60,000 BTU; largest residential system you can get) heat pump matched with an appropriately sized air handler (with electric backup heat). The house is incredibly well built with top-of-the-line materials, but the builder really SNAFU'd by installing only one system. The system did work as intended, but only as well as a single system could in such a large house; The first floor was always freezing, but the second floor was at least ten degrees hotter at all times. If you placed your hand under any of the vents on the second floor (all in the ceiling), the air was incredibly weak. Having two separate systems would have definitely solved the issue with cooling performance, but it likely would not have overcome the deficiencies of a heat pump; Heat pumps work great when it's above about 35°F, and are actually cheaper and more efficient to operate than a gas or oil furnace when it's above 40°F, but their heating performance steadily drops as it gets colder. Below freezing, the backup heat generally has to assist the heat pump, and also when it's defrosting; If you have gas or oil backup that's great, but the oversized toaster coils known as electric strip heat will run your electric bill into the stratosphere!

What this resulted in was a house that was rather chilly and drafty when it got really cold; When I stayed over during the colder months, the weak heating system did not bother me at all, as I just piled on the sheets and slept like a baby. The underpowered A/C really made summers uncomfortable though!

 

The house was built in 1981, at a time when the country was suffering through the second oil embargo, so I can understand why the builder did not go with oil heat...

There were no public natural gas lines out there (and as far as I know there still might not be), and propane was also relatively expensive at the time, so I truly do understand why the builder went with a heat pump; What I still cannot understand is why the builder only installed one heat pump! There is only one house in the whole neighborhood with dual-zone heat pumps, and I do not know if the house was originally built this way at the request of the original owner, or if whoever owned the house later did extensive renovation work to add the second system. The units are both Trane XE1000s, which means they were installed in 1993 or later and are not original to the house.

 

My aunt and uncle's house was built in 1981, and they bought it from the original owners in 1994; It had the original Trane/GE heat pump when they bought it...

The original heat pump failed in 2001 or 2002 and was replaced with a 2001 Trane XE1000 5-ton heat pump; GE-designed Trane A/C units and heat pumps are among the best units ever made in my opinion; I still see them in operation all over the country! My belief is that the unit at my aunt and uncle's house did not completely fail, but rather it developed a Freon leak or something expensive broke; Since the unit was 20 years old at the time, it was deemed more cost effective to just replaced it. The original heat pump was replaced in 2001-2002, but the air handler had a manufacture date of 2006 so that means they had the original one for at least four more years! As long as they use the same refrigerant, Trane products are generally easily compatible with each other, even if the indoor unit is decades older than the outdoor unit (or vice versa).

Lightning struck the house during a storm in the summer of 2008, frying both the alarm system and the A/C compressor; Insurance paid to replace both. In 2014 or so, the Trane developed a Freon leak and it was decided to just replace it; My aunt and uncle knew they'd be moving out soon, so they replaced it with a relatively basic Carrier heat pump and air handler.

 

My Grandma's condo, here in PA, is nowhere near as bad as my aunt and uncle's old house, but it is still a perfect example of why 2-story homes over a certain square footage should have zoned systems...

When built in 1993-1994, the house was fitted with a York heat pump and air handler with a Trianco boiler tied into the system as backup heat; The boiler was fueled by a communal propane tank, and instead of heating water and circulating through baseboard heaters, a fan blew over a large heating element tied into the air handler. This system was disabled long before my Grandma bought the house from the 2nd owner in 2006; The original York system also died in 2004 and was replaced with a bottom-of-the-barrel Goodman 10 SEER unit. The Goodman had electric backup heat...

I have no idea what the cooling capacity of the original unit was, but the Goodman was a 3.5-ton (42,000 BTU) model. The Goodman did an excellent job of cooling the first floor and basement, but was rather lacking upstairs; There was pretty much no airflow from the vent in the upstairs bathroom, but the vents in the upstairs bedrooms were adequate in my opinion...

There was also a vent in the living room that was rather weak if I remember correctly, but this didn't affect the cooling performance. The compressor failed in the Goodman in 2015, and with my help Grammy settled on a Carrier Performance Series unit...

I'd convinced Grammy to go with a 2-stage unit, but "half-ton" units don't with 2-stage compressors ("Half-ton" means 1.5-ton, 2.5-ton, 3.5-ton, etc; There is no 4.5-ton, and 5-ton is the largest you can get). Generally, it is ill-advised to replace an existing unit with a arger unit because the ductwork was sized for the smaller unit; However, a difference of 12,000 BTUs was not believed to cause any problems...

I was also absolutely sure that the Goodman was slightly undersized for the house, and the install company agreed with, so we unanimously decided on a 4-ton unit. The 4-ton unit did develop a slight refrigerant leak last year, which was fixed under warranty, but it has been largely problem free since it was installed in August 2015! The propane backup heat was never hooked back up, and the new Carrier system uses a 15KW electric backup heater.

 

The whole "less than 3,000 square feet" code requirement for skimping on dual-zone systems pisses me off...

Every house is different, and numerous factors including build quality play a role; Tract homes generally have the minimum required insulation and have 2x4 framing instead of 2x6. In most areas, even the high-quality homes will not do so good with only a single system if they are over a certain size; If I had my way, every 2-story house 2,000 square feet and above built in America would have dual-zone or at least a zoned single system!

@Plain Jane Taco has shared pictures on this thread of the two heat pumps at his home, which is a 2-story single-family of roughly 2,000 square feet; Some people might call that overkill, but to me it makes perfect sense! The biggest issue is not whether the house would be just fine with only one system (which it probably would be), but overall efficiency; I know people with 2-story and 3-story houses way less than 2,000 square feet where the central A/C just can't evenly cool the entire house! With multiple zones, you can raise the temperature on the first floor when you go to bed, to save energy, but freeze out the second floor; With a single system, you generally have to freeze out the first floor to make the second floor even remotely tolerable!

Even seemingly identical floor plans in the same development can have different heating and cooling needs; These include, but are certainly not limited to...

• Number of windows
• Color of roof shingles
• The position of the sun relative to the location of the house
• Seemingly minor additions like sunrooms, bay windows, and small "bumpouts"