Single stage vs 2-stage A/C in Texas - Good?

4 years ago

Hi - I have two HVAC units in my home (upstairs and downstairs) both are over 20-years old and I'm looking to replace them. Most companies from whom I have received estimates are pushing for the variable speed A/C. Only one shop is suggesting to stay with the single stage, but to pair that with a furnace equipped with a variable speed fan. Based upon a lot of web-browsing, upgrading to a 2-stage A/C may provide a more comfortable interior? My electric bills are not an issue, so it's not about monthly cost savings. Any advice from the professionals here would be welcome.

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Austin Air Companie
4 years ago
What part of Texas? (It's huge--- I'm in Katy, Texas area)

Certain areas of Texas are more dry than others. (Less humid) Certainly any area can have bouts of high humidity here. So sometimes this is a more difficult decision.

What is important to you?

Humidity reduction is achieved when the AC is running. A single stage AC main function is to drop temperature. While you will get some dehumidification from that it's primary function is to drop temperature.

Because we live in a hot climate people are more prone to wanting a larger AC unit thinking that will work better, when in fact it will make things worse.

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2 stage AC --- It will run upwards of 90% of the time in 1st stage AC mode or more or less dehumidification mode.

However, this systems short comings become abundantly clear in the shoulder seasons of our Texas climate. Because 1st stage is approximately 70% of the capacity of the machine -- in the shoulder season that first stage is often times over sized and does little to combat high humidity that certain areas of Texas are prone to.

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Variable Speed AC --- not all are created equal here. In some cases the system in question may be limited to 5 stages, if paired with legacy controls it may be no better than the 2 stage AC unit above.

A true variable speed AC will excel at a number of things - depending on the brand / model chosen could have as many as 75 speeds. In this realm it's more about 'load matching' the structure.

Because of the ability to ramp very low gives this kind of AC unprecedented dehumidification. By reducing humidity a mere 5% will make you that much more comfortable than merely dropping temperature alone.

It may become 'too cold' than what your current setting makes you think you are comfortable at. So if that happens, you raise the set point on the thermostat. Which will reduce your electric bill on top of the very high efficient Variable Speed AC unit.

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Is it for everyone? no. A variable speed AC will cost more up front. Over time it will pay for itself... how fast will depend on a wide variety of factors.

If you plan to sell your home soon, it could help you sell the home sooner. But you may not recoup the investment.

I recently installed a Variable Speed AC at my home in Katy, Texas.

I service the Katy, Texas area.
sktn77a
4 years ago
If you're on a shoestring budget then a single stage AC with a fixed speed blower is what you'll get. If you have a little more to spend (but not enough for a 2 stage or variable speed system) then a single stage condenser with a variable speed blower is the next best step. The variable speed blower can be set to lower its speed when more dehumidification is needed. Not as good as a 2 stage or variable speed system but better than the fixed speed blower. After that, it's really dependent on how much comfort you can afford! The two stage system is good for most climates but cooler humid locations can benefit even more from the variable speed system.

Ya pays yer money, ya takes yer choice!

😐
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Single stage vs 2-stage A/C in Texas - Good?

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Austin Air Companie

sktn77a

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