Did HVAC become a "one size fits all" deal?
My wife and I are having a new home built in a subdivision. We've upgraded everything (flooring, lighting, cabinets, etc.,) to avoid moving into a new home full of "builder grade" stuff. Unfortunately, upgrading the HVAC system was not an available option. As a result, I'm stuck with lower end equipment. While I'd prefer to upgrade to better quality equipment (stuck with Lennox 13ACX AC and Lennox ML180UH gas furnace), I understand their desire to keep costs low and I don't think i'm getting total junk.
My issue is with the fact that all the homes I've looked at have the same sized unit! These homes range from 2 story ~1,950 sq ft. homes on slabs to ~3,400 sq foot homes on finished walk out basements. All the homes I saw so far have 13ACX-030-230-12 AC units outside. Some quick math tells me the builder has decided that 2.5 tons of cooling works equally well for homes of all sizes.
Before I address this with them (not in a "can I upgrade" way, but more in a "I won't go to closing with a poorly designed HVAC system in place" kind of way) I'd like some opinions. Unfortunately, I can't call in outside companies, as the contract stipulates that no outside vendors/contractors are allowed on site prior to closing. As a result, I'll provide as much info as I can here, and humbly ask for your assistance in providing well articulated evidence that the HVAC system is improperly sized (or, evidence that I don't know what I'm talking about and that I have nothing to worry about).
Info on my house:
Located in the Northern area of Virginia (physically located near the northern tip of the state)
Front of the home is North facing, rest of the home has excellent shade either by large trees or a combination of elevation changes and neighboring homes.
3 level (2 stories sitting on a walk out basement)
~3,150 total (1,100 first floor, 1500 2nd floor, 650 in the basement. It should be noted that nearly all finished space in the basement is in the "daylight" portion, meaning not actually below grade)
R-13 in the walls, R-38 in the attic, vinyl siding
Low-E windows (~17 of them, 7 south facing, 8 north facing, 1 east, 1 west), 1 glass door south facing, 1 sliding door also south facing.
Based on that info, I feel the system they intend to install is undersized.. Am I nuts? Thanks for reading my novel, and thanks for any info/links you might be able to provide!
Go to the county I am going to guess Loudon and go to permit review with your lot # and permit # and speak with someone in planning review. A manual J load calculation would need to be submitted for your house.
Originally Posted by Fizzle
Builders will enter a generic size for the entire project. One size does not fit all.
With all of you shade, 2.5 tons is possible. But a load calc would be best. A excelletn upgrade would be a 2 stage AC with a zone system. A zoned system can be undersized slightly, and often perform best that way. But you need ot have properly sized ductwork. Defnitely get a 2 stage furnace with ECM or vairable speed blower motor. THese can to controleld with a humidistat and their speed reduced to remove humidity on demand. WOrth the small increase in price.
Honestly, if you can, I'd get a credit form the builder and contract your own HVAC company if possible and have them do the load calculation and ductwork layout... espcially with a zoned system.
I can tell you from personal experience that going fom a oversized system to a properly sized system...even better one that's 2 stage is night and day in terms of how even, quiet and drier the air is. Energy use is even lower than what hte SEER, EER improvement woudl indicate due ot longer run times. Having now experienced it myself, I'd much rather have a slightly undersized system than an oversized one.
To answer the question posed by how you titled this thread; NO! HVAC sizing is NOT a "one size fits all" deal. Never was, never will be.
As for how that applies to your tract home builder, I'm not sure what form or how much remedy you might have, since the contract stipulates you can't do much about their choice of contractors. It's also sad that in your case, a home buyer who not only has funds to upgrade the glitter but also the HVAC, the builder walks away from the latter. Why would that category not also be upgradable? More money for the builder, you'd think.
If you want to get a general idea whether what they are installing might be up to the task or possibly over/undersized, you can get Don Sleeth's HVAC-Calc from this site and run a calculation yourself. Just be sure to put in as much information accurately as you can, as that will determine how useful your results from the software will be.
Building Physics Rule #1: Hot flows to cold.
Building Physics Rule #2: Higher air pressure moves toward lower air pressure
Building Physics Rule #3: Higher moisture concentration moves toward lower moisture concentration.
Shophound X2. Remember that you're writing the check!!! And you don't want to live in a house that is uncomfortable to live in!! Simple as that. As a HVAC contractor I see LOTS of homes with marble countertops, great kitchens and horribly installed HVAC systems. Heck fire I was in one today!! Beautiful home with 3 finished floors, and nearly ten degrees difference between EACH FLOOR!!! Yep, 65 in basement, 75 on main floor, and SURPRISE.....85-88 degrees in upper floor. Entire home finished and homeowner unhappy with comfort.......P.S. We did not install system, but WOW was it simple to see why the installing contractor was not welcome back by anyone OTHER THAN THE BUILDING CONTRACTOR. Homeowner moved into home in early winter, and found the basement cool, however had no idea what would happen in the summer. Needless to say, he's hot!!
Originally Posted by wahoo
It's worth noteing the the quality or how fancy the HVAC equipment is, how fancy the controls are is irrelevant if the ductwork isn't designed right and it's not sized right. Any contractor on this board can make a builder grade 13 SEER Goodman with a 30 year old mercury thermostat more efficient and reliable than a improperly sized and installed Trane XL20i 2 stage with the super fancy touchscreen.
The problem with new construction is you get the hvac that fits the budget that the builder sets, And he wont be living there if he is so confident in the contractor and his ability make them put a comfort guarantee in writing ,all rooms with in 3 degrees of each other
Advice and replies thus far are greatly appreciated! Like I said in the OP, I understand that certain corners are going to be cut because builders have to advertise an inviting "base price" for a home. As such, I knew before I walked into the sales office that I'd be paying to upgrade essentially everything in the house. My first question was HVAC related and that's when I was informed that the mechanical systems were non-negotiable. My assumption at the time was that I'd get a low end but at least properly sized/installed system. Now that I know what's going in, I don't think I'm even getting that.
I've already explained to my wife (who's fallen in love with the house) that we won't be closing on it if the HVAC system isn't properly engineered. Cabinets can be ripped off the wall and flooring replaced, but replacing improperly sized duct work in 3 finished levels of a home is going to leave a mark!
I'm not an HVAC professional, but my father was (actually, he was a master HVAC mechanic, master plumber, master electrician, and master gas fitter and later a mechanical estimator for some of the largest firms in the country). Over the years, I learned a fair bit about sizing and installing systems.
Something else I learned from him and in my own career as an engineer is that when a job, a design, or a dispute involves your personal life your best best is to ask for outside help
The house needs 2 systems repeat needs 2 systems for the best comfort and efficiency you can not beat 2 systems on multy level,the reason you can upgrade carpet ,tile and granite is the builder makes huge money on them .they have a hard time making money on hvac upgrades