re: Planning for HVAC system and things I need to know

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The vari speed and the dehumidifier probably won't be necessary.

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Meh, like Wick said, the variable speed is great to have as the unit can run at low speed while dehumidifying. If you have a single speed, the unit will overcool and stop before dehumidifying.

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I did both and the humidity stays in check without the dehumidifier.

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If you have a great insulation package, sure. But I would add you can only have too much dehumidification if the house is too dry for your comfort. Remember it's more efficient to cool drier air, so as long as you can stand the lower humidity level, your AC will work easier to get to set temp.

I do agree with the idea of not liking a dehumidifier to be tapped into the AC directly. I'm just not a fan of modifying an engineered system like HVAC to add a 3rd party system. Of course, the sales person will tell you the system will do everything they advertise, and more, while not mentioning the drawbacks.

There are some really good, standalone dehumidification systems available. I believe those are the best benefit for the dollar.

You can accomplish a lot with deep enough pockets, but at some point the returns don't justify the expense.

Yeah, I could have stated that more clearly. I believe I meant to say that a variable speed unit would work better as it can run more slowly without overcooling the space, while still dehumidifying "more completely".

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The vari speed and the dehumidifier probably won't be necessary.

I did both and the humidity stays in check without the dehumidifier.

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My only experiences have been one-stage (single) HVAC systems. I've been very fortunate to never have experienced any HVAC issues in my current home - 18 years. I attritube that to a good product, and an even better install -- and preventive maintenance.

The only "downside" to the single stage is that relative humidity tends to creep up inside my home. I use 2 portable dehumidifiers and they certainly make a meaningful impact.

After posting in here, I'm doing more research on the variable speed HVAC systems, and this looks like it may be the answer and won't "require" me to add a whole home dehumidifier system. I had initially thought that a variable speed system and a whole home dehumidifer system were almost a requirement for one another. I am glad to learn I was wrong.

I do believe in the concept of "less is more" and with this new information (to me), this helps.

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A lot of unnecessary shite to break and tech will have to order because he doesn’t carry it on his truck. Go basic, you’ll be a lot happier.

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I just responded to another poster in this thread, and I now agree. Thanks for helping me come around to this conclusion.

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I think WillieC has spent way too much time watching Matt Risinger. I

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I'm glad I posted here ... just saved quite a bit realizing that a variable speed will more than effectively handle dehumidifcation and that a whole home dehumidifier is most likely not necessary!

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I'm glad I posted here ... just saved quite a bit realizing that a variable speed will more than effectively handle dehumidifcation and that a whole home dehumidifier is most likely not necessary!

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Whole house dehumidifiers are more common at more northerly latitudes in humid climates because they have much longer “shoulder seasons” (spring & falls) where their HVACs are not running for long times within a day to effectively dehumidify the air. 80%+ of residential HVACs installed in the USA are single stage systems.

In the Deep South, we run HVAC for cooling 10 months a year, and HVAC run times are often long, so we usually get good dehumidification without the need for a dehumidifier for most of the year, because of the long HVAC run times. This assumes the HVAC is not over-sized and/or that the house is reasonably “tight”, non-leaky, in regard to air infiltration.

I seriously considered installing a whole house dehumidifier when I did a changeout of my single stage HVAC 3 years ago. Did all the homework. And it would be an easy add on. My house is 30 years old but is tight in regard to air filtration as shown by a blower door test and my HVAC tonnage is properly sized according to manual J heat load. It’s very rare that relative humidity in my house exceeds 55%, and the few times that occurs is during our short shoulder seasons where it’s humid outside and still relatively cool - so HVAC is not running much or very long.

Sometimes it would be good, and necessary, to have a whole house dehumidifer in a house in our area, but other times it might be better to invest those same $ in air sealing the house to mitigate humid air filtration into the house causing the issue in the first place. But then you have the risk of having a properly sized HVAC becoming over-sized because you tightened up the house to air filtration - crazy isn’t it……lol.

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You might have to get quotes from a bunch of HVAC companies before you find one that actually knows what their doing and actually gives a shite. 90% of them don't.

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Then hope that the guy you're talking to has some connection and responsibility for the work that gets done and isn't just a used car salesman completely disconnected and oblivious from the people who show up and do the work.

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Are you suggesting then that a dehumidifier might not be necessary?

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I am not an HVAC person but in 2006-2007 I did a lot of research when we built our house. 2700 sf, 2 story with open cell spray foam all the way around. We installed one upstairs and one downstairs 3 ton Carrier infinity 21 seer, variable speed units, which was top of the line at the time. The calculations would show that the HVAC are oversized but the home has never had humidity issues and when the units kick on, you know it, it cools quickly if you are changing the thermostat. Otherwise the unit normally runs at low speed.

I'm sure a lot of improvements have happened over the past 20 years, but we have never felt the need for a dehumidifier.