I need HVAC help in Tomball

[Txhuntr2]

Any HVAC guys out there? Our house is 2400sq ft and 2 stories. Since we built it about 6 years ago, we've never been able to keep the indoor humidity under control i the warmer months. Downstairs, I can usually keep it in the high 50% to low 60% range but upstairs its much higher. It's usually 65-75% , sometimes as high as 80% and never under 60%.

I have a single ac unit and multiple zones and the ac is not over-sized (so I've been told). The house is newer and I cant find any air leaks in the walls or widows etc. I just had an ac company come out and the system is cooling/working fine and he couldn't find any leaks in the duct work but he was only in the attic looking for about 5 minutes.

What can I do to lower humidity? Do I need a whole house dehumidifier. How much do they cost?

[Blitz]

I went through this last year before I purchased a new system. I spent a lot time researching stuff. Here’s what I’ve determined, and I’m not an hvac tech.

Single stage units are designed to turn on when it hits the temperature threshold and turn off when it hits its target temperature.

Multiple stage or fully variable (like the one I bought), runs longer and spends time removing the humidity from the house. Basically, humidity can’t be removed if the unit is off unless you have a separate unit for that.

[TeamAmerica]

How many sf upstairs?

[Txhuntr2]

How many sf upstairs?

1200 up 1200 down.

[Txhuntr2]

I went through this last year before I purchased a new system. I spent a lot time researching stuff. Here’s what I’ve determined, and I’m not an hvac tech.

Single stage units are designed to turn on when it hits the temperature threshold and turn off when it hits its target temperature.

Multiple stage or fully variable (like the one I bought), runs longer and spends time removing the humidity from the house. Basically, humidity can’t be removed if the unit is off unless you have a separate unit for that.

Thanks for the reply. We have a single stage but we have a digital thermostat that detects humidity. It allows the ac to keep cooling up to 3 degrees cooler than the set temperature in order to keep dehumidifying to the desired humidity. Problem is, most of the time it stays at 3 degrees below set because it never gets the humidity down.

[Blitz]

Ya. That’s the problem with single stage units. They are either on or off.

I have fully variable carrier that I set the humidity level I like. It stays running at a lower level to achieve the set humidity. Makes a world of difference.

[Txhuntr2]

Ya. That’s the problem with single stage units. They are either on or off.

I have fully variable carrier that I set the humidity level I like. It stays running at a lower level to achieve the set humidity. Makes a world of difference.

Is switching to a variable speed blower enough or would i need to replace the entire system to get that feature?

[Blitz]

You might be able to do it. That’s definitely an hvac tech question.

[mavrick]

I would add a second unit. Much easier to manage with less parts to fail.

[Greenheadless]

Tagged

[StrayDog]

How did they determine the unit was sized correctly? To answer your problem completely and accurately it takes a fair amount of math.

In terms of HVAC talk there are actually two parts of your AC’s capacity:

1. Sensible Capacity - laymen’s term, this is what lowers the thermometer temperature.
2. Latent Capacity - laymen’s term, this is what lowers the humidity

Closer to the coast where the outside air is more humid you need more latent capacity to deal with humidity. Your thermostat just really cares about sensible heat or thermometer temperature.

If I were a betting man I’d guess your problem is twofold:

1. Your unit might not have enough latent capacity
2. The design approach of a single stage / single unit just doesn’t meet the design needs of your house.

Personally, I’d get the AC figured out as a dehumidifier is just a bandaid. Find and AC company that will run a true heat load calculation on your house and tell you the sensible, latent, and air flow requirements based upon actual design temperatures. Then they can compare this to the equipment you have installed.

If you don’t do this, unfortunately, you’ll just be tossing money and hoping you get lucky with a solution.

[elliscountyhog]

Is switching to a variable speed blower enough or would i need to replace the entire system to get that feature?

Whole system. They are fantastic!!! We sell the Trane XV18 or XV20.

[kmitchl]

Sounds to me that the air upstairs is not getting turned over as often as the bottom floor. If the air goes over the evaporator core it’s going the drop the water. Are the thermostats set the same? If so the upstairs zone should be calling for cooling more often than the downstairs and the upstairs humidity should drop.

[bowhntrmatt]

Single stage equipment and zoning are two things that shouldn’t mix. Especially if there is a barometric bypass in play. It makes it tough to dehumidify when only a small portion of the air is coming from return and the rest is getting recycled. Dew point is too low.

[Uncle Saggy]

Is this a central return system?


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