Originally Posted by KrisZ
Originally Posted by dnewton3
Originally Posted by skyactiv
Cool is not cool.
The higher SEER units are not all about efficiency.
If your well off and want the utmost comfort you'd get a variable speed air conditioner. It can pull more humidity out of the air running it at a higher temperature.
Good if your wife is chilly at 75 where you want it and she'd rather have it at 78 which you cant sleep good at night as an example.
Many people feel comfortable at a higher temp if more humidity is removed.
People who have over sized systems are the ones that typically set the temp lower to stay comfortable as otherwise the system would kick on and off too much
not pulling humidity out very good.
Expensive? Yes. Not as reliable? Potentially.
My parents had such a Trane system installed and it's magic. The HVAC people also installed a whole house surge protector for them.
Variable and two-stage units dehumidify indoor air more effectively.
The calculation for SEER has nothing to do with relative humidity in the house. And, units with more expensive components will be more expensive to replace. Variable speed compressors and v/s blower motors are more expensive to purchase and replace. It is true that v/s systems can pull a bit more hum out of the air, but "cool is cool" is true. I am talking about actual temps, not those perceived with RH.
I have a slightly oversized system on purpose. A simple, single speed oversized system. I use a small dehum unit in the basement to knock the humidity down, and the a/c can short cycle to keep the house cool to the temp I select on the t-stat. And when it gets gawd-awful hot outside, I'm still able to hold 75 ID when it's 100 OD. Smaller systems work fine until the hot poo hits the fan, and then they cannot keep the temps down. My former neighbor bought a "properly sized" system a few years ago. Then when it hit 101F outside, his house was a nice 80F inside, because the system was sized for the "normal" expected heat load and not an extreme heat load. When it's 80F inside the house, even if it's DRY air, its still hot, dry air. My system is sized for a 30deg temp delta; it will hold 75 inside even if it's 105 outside, and it would be dry, too. And when it's 85 outside, although the system short cycles, the little dehum unit keeps the air dry. Best of both worlds. And my old-school single speed components won't cost an arm/leg to replace after warranty. I can buy the replacements from generic sources, too. Try that with a brand-specific motor that has unique program language in the motor control board; they've got you over a barrel when you have to buy their motor to make the system communicate properly.
Skyactiv is spot on and what you are doing with your oversized, single stage system and a dehumidifier is exactly what a two-stage or variable system is designed to do. That is you have the capacity when you need rapid cooling, but once the desired temperature is reached, the system switches to lower capacity mode. In that lower capacity mode the system may run continuously, but it's usually at around 30% of the full capacity, so it saves energy, pulls the humidity out of the house a lot more efficiently and is actually better for equipment longevity, as it is the stop/start cycles that are the most taxing on the whole system
It's kind of like cylinder deactivation in modern engines, except it actually delivers on the benefits like comfort and energy savings.
In terms of the SEER rating, he's not spot on; he's wrong. SEER calculations have nothing to do with RH. You can get a high SEER rated unit that's still single speed. The SEER rating and the ability to control humidity are not directly co-dependent.
A high SEER unit can control humidity well or not well; that depends upon other system design topics.
A low SEER unit can control humidity well or now well; again - design dependent.
My point is that SEER (high eff units) does not assure low humidity. High SEER systems which ALSO happen to be multi-speed and utilize other integrated system tools (t-stat and hygrometer) can do a great job of controlling humidity. But his comment implied that high SEER units always control humidity well; that flat ain't true.
Temps are temps; hence my statement that "cool is cool". Cooling capacity is not directly related to RH in the house. Perceived (sensible) temps due to RH control are a completely different topic.
As for controlling the household cooling and humidity I would agree; the end result is the same between using an advanced v/s system and my slightly over-sized system with separate dehum unit.
Except that mine costs less to purchase initially, costs about the same as a v/s system to operate because mine short cycles, and is cheaper to repair when components fail after warranty ...