Hi, Joe,

The relative humidity level in your home will fluctuate based on a number of variables, the most significant of which is outdoor conditions. If the outdoor temperature is in the 90's F and the relative humidity is 80% or so, then indoor conditions of 70F and 55% relative humidity might indicate really good performance of your system. What's more important than the numbers is whether you are 1.) comfortable, 2.) there is no cupping/crowning of hardwood floors or issues with interior trim, and 3.) the relative humidity is lower than that which supports mold and mildew growth.

You should try to get the indoor humidity down below 50%. If you haven't checked yet, see if you blower speed can be reduced to improve dehumidification. Don't over do it though (10% - 15% max) or you'll freeze your coil!

You might need a dedicated, whole-home dehumidifier like a Santa Fe.

If you do decide to go this route; Make sure you get one with a fresh air intake so you can purge indoor pollutants via positive pressure. I usually install them in cust homes by using the existing supply ducts and installing a dedicated return (avoiding air handler completely) Ideally, <50% RH year round (35% at the min)

Another option is what @sktn77a suggested, but if this just started happening, I'd get the unit checked out to make sure it's working as expected.

Hopefully Charles Ross is correct and the outdoor conditions have a big impact - we're in Houston and during the summer when its often 90-100F+ and humidity is >90% (ie today it's 95% humidity), the lowest we can keep our house is 50% or slightly higher (early morning it rises indoors for some reason). We recently remodeled (down to the studs, new insulation, etc) and it's still >50%. During the fall, winter and spring, we're down sub 50%. At one point before we remodeled, we had a portable dehumidifier, but was still difficult getting it to stay below 50% when it was >90% humidity outside.

I usually go by dew point for how muggy it is outside. Dew point is a better measure of how much moisture is in the air. This summer has been brutal by me. Dew points usually 70-73% even when humidity isn't very high. We have a whole home dehumidifier on our walkout basement unit and use a portable unit on our main level. Usually can keep main level between 45%-50% humidity. Our walk out basement level is usually between 42%-45%. I can deal with up to 54% and then I start to feel icky.

Outdoor humidity today has reached upwards of 98%. Currently 97% at 83°FC. Indoor setpoint of 77°F. Indoor humidity earlier in the day was 57% per the Honeywell thermostat (no direct humidity control capability on the system). Currently (early evening) 59%, presumably due to shorter runtimes with outdoor temp dropping.

I have been having issues with moisture throughout my house flooring with no leaks at 70°my humidity level stays around 55%

A 55% humidity level at 70 degrees F is at the upper bound of comfort in my opinion. If this was occurring in my house I would be trying to figure out what's wrong with my AC.

How large is you house? Does the AC run in short cycles? Is the condensate drain working properly? Is the thermostat set to on or auto? When was the last time preventative maintenance was done?

If this is a single stage AC, it may be possible to lower the fan speed. You may be also able to change the cycle time per hour setting on the thermostat.

Comfort will be assessed differently by different individuals. The good folks at ASHRAE did a pretty comprehensive study on occupant comfort as a function of temperature, radiant temperature, clothing level, metabolic rate, humidity and air speed (ASHRAE Standard 55 Thermal Environmental Conditions for Human Occupancy.) A temperature of 70F and 55% would fall well within the comfort range for most people. For relative humidity levels above 50% the concern shifts from comfort to indoor air quality considerations; in particular, the potential for mold/mildew growth.

Hopefully Charles Ross is correct and the outdoor conditions have a big impact - we're in Houston and during the summer when its often 90-100F+ and humidity is >90% (ie today it's 95% humidity), the lowest we can keep our house is 50% or slightly higher (early morning it rises indoors for some reason). We recently remodeled (down to the studs, new insulation, etc) and it's still >50%.

BW_TX, Houston area is in a league of it's own when it comes to humidity issues. Most of the time Charles as well as others like to dismiss things as it relates to the Houston climate. (I believe this has to do more with me, than it does Texas in general. LOL)

Charles is more about spelling out technical jargon in dismissive rhetoric. He's a builder in Norfolk, Virginia that climate may occasionally have some similarities but not the level we deal with here in the general Houston area.

Mike_home is a home owner that lives in New Jersey.

Humidity or the lack there of is a complex continually evolving problem. Especially for climates like Houston. People like to put HVAC in a box and set certain conditions with tight parameters. HVAC is a trade that because of these climate differences / experience differences you can have these discussions / life experiences etc. evolve into arguments of all shapes and sizes.

People at times get tired of this kind of this constant rhetoric calling them "pissing matches".

After 29 years of doing this for a living... I can tell you it's not going to end with this thread either.

I service the Katy, Texas area.

(Houston is large geographically -- window time is the death knell of HVAC service... as always your mileage will vary.)

Ray,

While it can get colder here in coastal Virginia than is typical in Houston, the summertime humidity isn't all that different. Indeed, the summer design conditions for HVAC aren't all that different. Here are the design conditions per code:

Houston 32 F winter; 94 F d.b. summer; 79 F w.b. summer

Nofolk 22 F winter; 91 F d.b. summer; 78 F w.b. summer

Mike_home is a home owner that lives in New Jersey.

Thank you for the complement. Albert Einstein was also a homeowner who lived in New Jersey. If ever you are in the area I can show you the modest house he lived it. I am confident it was built with no AC in case you are wondering. He was probably not very knowledgeable how to control humidity with a central AC system.

I’m a home owner in Tampa, Florida. We are getting close to CO in our new build. From an air conditioning design perspective, I opted for for adding a Santa Fe Ultra Aire 120h with a dedicated fresh air intake to my system. I’m hoping it will be enough to keep my 3,200 sq ft home at or below 50% RH. 120h dehumidifier is top right in the photo. We are just about to power-up the system so I’ll report back on how well its working.

While it can get colder here in coastal Virginia than is typical in Houston, the summertime humidity isn't all that different.

Just printing averages from one area to another doesn't really do the situation justice as these ranges can fluctuate wildly.

As BW_TX noted humidity as high as 95%. Houston climate in general as well as Katy, Texas deals with humidity all year long.

It's not just a summer festival event here.

Reading further I was merely noting where everyone lives because? Climates are different and thus the perspective of those that live there.

Dehumidifiers: For the Florida area person who chimed in... yes whole home dehumidifiers are an option that "control" humidity because these are separate systems dedicated to a particular function. In a new home build this extra cost probably isn't that prohibitive is my guess. But dehumidifiers cost money to operate. Depending on a host of various factors (utility rates, run time etc.)

A dehumidifier is another refrigeration system on top of the AC system for your home. In addition to utility costs it will require service, maintenance, repairs and eventual replacement.

Is a dehumidifier wrong? no, it's another option in a list of options. All dehumidifiers I have ever sold or worked on are warrantied for 5 years (parts only). So the time one will last is rather short in my experience.

Why spell it out like this? HVAC is a complex market built on providing comfort. Comfort "a feeling" --- doesn't mean the same thing to everyone.

How hot is hot? How cold is cold? How humid is humid?

Temperature and humidity run in opposing circles. You can have high humidity regardless of what the temperature is. That can be a problem for areas of the country that have high humidity all year long.

The winter for northern climates is often dry. So they add moisture to the air via a humidifier --- which is yet another appliance to maintain, repair and replace.

For the Houston area (Katy, Tx included) a humidifier is a waste of money. Can it become dry here? yes. But it is often so short it's not worth chasing that rabbit in the hole from which he came.

"For the Florida area person who chimed in... yes whole home dehumidifiers are an option that "control" humidity because these are separate systems dedicated to a particular function."

Clearly, you don't understand the difference between equipment and installed systems. A dehumidifier is a piece of equipment. It can be installed to operate as a separate system (either a portable unit or an installed unit with dedicated duct work,) or integrated with a central HVAC system. If you look at the photo provided, you'll see that the dehumidifier is integrated into the HVAC system--not installed as a separate system. What we can't infer from the photo is how the dehumidifier is controlled.

I have two dehumidifiers in my home. One is integrated in the HVAC system for the 1st floor and one is integrated in the HVAC system for the 2nd floor. They operate during "shoulder" seasons when neither heating nor air conditioning is required, but relative humidity needs to be controlled. During the portion of the year when air conditioning is required, the air conditioning systems provide adequate dehumidification.

"Just printing averages from one area to another doesn't really do the situation justice as these ranges can fluctuate wildly."

The temperature data cited above are not averages. They are code-required design temperatures for particular areas. Your lack of familiarity with the presentation is evidence that you don't do HVAC design--or at least any design that is subject to permit review and approval. Indeed the range of temperatures can be wide--even if the range is stated as the difference in dry bulb summer and winter design temperatures . That would be 94F - 32F = 62 degrees F in Houston and 91 F - 22 F = 69 F in Norfolk VA.

The challenge designing for mixed climate zones-- like our mixed-humid coastal Virginia climate zone, is that a portion of the year the climate conditions are that of a heating climate zone and a portion of the year the climate conditions are that of a cooling climate zone. Our heating systems need to be every bit as robust as northern systems and our air conditioning systems need to be every bit as robust as systems installed in states south of ours.

What does the humidifier do when run separately, Charles?

The air coming out could be as warm as 90F maybe warmer. A builder won't tell you such things. So yeah you can run them separately.

Not much of a problem in chillier weather and high humidity, but what about other times? Some people may find this perfectly fine, some living in warmer climates may not.

You can set them up to force the AC to run while the dehumidifier is on. But what about when it's chillier & high humid? Comfort remember?

This is why operational costs are high with dehumidifier and AC. The AC is geared toward lowering temp, the humidifier adds heat during operation to "control" humidity.

If you want control of humidity there is no better way than a whole home dehumidifier tied to your existing HVAC system but is that the best? Are there concerns to have?

To paint a picture for you:

Got a service call long time ago. The complaint was high electric bills / too hot randomly or intermittently.

The customer in question had a whole home dehumidifier tied to an HVAC system. dehumidifier controlled by humidstat on the wall next to temp controlled thermostat to control AC & Heat.

Someone set the dehumdifier to 40% via humidistat on wall. The dehumidifier under that setting here in Houston climate would never or rarely shut off. The AC would cycle off on temp via thermostat, the customer would wake up sweating because? The electric bill was high because?

An air conditioning system is designed to deliver occupant comfort. That means lowering temperature (the sensible heat load) and removing moisture (the latent heat load.) A properly designed air conditioning system does both. The water draining from the condensate line is evidence that an air conditioning system is dehumidifying the air.

The problem is how to dehumidify a home when air conditioning isn't required and relative humidity exceeds a comfortable level or causes movement in hardwood flooring and trim or puts the home at risk of mold/mildew growth. That's what often happens in my (mixed-humid) climate zone during so-called "shoulder" seasons and that's when a dehumidifier shines. If the amount of heat contributed by the dehumidifier raises the indoor temperature enough, the air conditioner can kick on and bring it back down. The initial and operating costs of a dehumidifier are the prices paid for regulating the indoor environment just like the other components of a HVAC system.

This morning sitting in my office the RH in here is 44% this morning from running the AC inverter to 72 over night. ( same as I do every night)

here is something to compare it to, maybe dadoes would like to chime in again and tell us where his is resting at... probably more argumentative than anything else but what thread on this board isn't argumentative.

It's been quite humid here as of late. The Inverter doesn't give me any specific control over RH, it is operated from temperature alone. So even cooler weather here I would have to lower temp further under cooler temps and high humidity.

To figure the advantage why I chose what I did... you'll have to climb down into the rabbit hole with me.

click to enlarge comparison of a few days ago....

I don't have a control to push RH to any level. This is a "function" of the inverter when it runs. (the carrot, here bunny, bunny, bunny.) LOL.

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If the amount of heat contributed by the dehumidifier raises the indoor temperature enough, the air conditioner can kick on and bring it back down.

Sure Charles, but you failed to grasp the story which is often the case. The complaint was that they were waking up hot. You have your controls outside the room in which you sleep. The thermostat doesn't know that 90F air is blowing on you because the humidity is high and the whole home dehumidifier is running.

This morning in my house the outdoor conditions are 72 degrees with 99% humidity. It has been raining non-stop for the past 8 hours. Indoors it is 78 degrees (which is the usual thermostat set point) and 42% humidity. The Carrier Infinity AC does a good job of controlling the humidity.

You bring up a good point Mike, inverters aren't all created equal. Carrier limits their inverters to only 5 speeds. While the Bosch Inverter doesn't do this, the conditioning steps ramp up and down in 1% increments from about 20-25% of capacity. Depending on model chosen you have over 60 speeds of cooling performance with the Bosch Inverter.

This doesn't mean Carrier won't work for some. It's about how the equipment works too. Infinity systems are a broad line, you need to pay attention to what you are actually buying. Don't get duped by fancy words like "Infinity".

It's dangerous to generalize that one type of equipment or one manufacturer's product line or one system configuration is a one-size-fits all solution. It's equally dangerous to assume what works in one climate zone will work just fine in another or to use a rule of thumb when sizing equipment. Design is critically important. Unfortunately, most HVAC contractors lack a design competency.

I have a pair of Carrier Infinity 2-stage AC condensers with variable speed 3-stage gas furnaces. The coils are oversized by 1 ton on each of the furnaces. Two stages of cooling operation works well. I tend to set the thermostat higher than most people (77-78). I find the temperature is comfortable with humidity in the 40-45% range. The second floor tends to be less humid then the first floor where the kitchen is located. The basement stays very cool and dry.

The manufactures AFAIK, do not make climate specific equipment.

It's up to the home owner to choose what they think is best after they look at and understand all their choices. To choose or not choose an Inverter? It costs more up front, so that right there will eliminate it as a choice for many.

Things like how long will you own this house, etc.

When compared to options about lowering humidity, an Inverter AC is a choice that *may* allow you to skip the expense of a whole home dehumidifier.

Every situation is different, every climate is different, comfort means what to you? (That why it's a rabbit hole discussion.)

I am merely continuing the conversation to show there is an opposing side. (It's a choice among many)

"It's up to the home owner to choose what they think is best after they look at and understand all their choices."

Agreed. The problem is the lack of HVAC contractors who know more than the homeowners do after reading a couple of brochures.

The point of my post is to share my experience d of controlling the humidity in my house in NJ. It is possible to have good humidity control on cool humid days if you have AC equipment that has the features to reduce humidity, and it is sized and installed properly.

Heat pump inverters are not popular in the New York City metro area due to high cost of electricity and the relative low cost of natural gas. Most AC equipment is sold by SEER rating. If is unfortunate but that is how most HVAC contractors operate.

@mike_home,

Not looking to pick a fight, but your specific example isn't the best illustration of the point you wish to make. Your indoor air temperature at 78F is significantly higher than the outdoor air temperature of 72 F. Looking at a psychrometric chart with my aged eyes, increasing the air temperature from 72F outdoors to 78F indoors decreases relative humidity about 20 percentage points by itself.

While air conditioners do indeed function to dehumidify indoor air, their ability to do so is limited to times when they are operating. If there is no call for air conditioning, their ability to dehumidify is zilch. Some of the more sophisticated systems will have a dehumidification mode, but they'll need to cool indoor air below setpoint temperature during times when no cooling is called for.

In my mixed-humid climate zone-- where we get two shoulder seasons each year of approximately three weeks each--I find a dehumidifier is a good investment to ensure occupant comfort, but equally important to minimize the potential for mold/mildew growth. I had mildew take root in one home and it's darn difficult to get rid of once it gets established (kinda like the in-laws moving in.) More sophisticated air conditioning systems such as those with multi-stage compressors and variable speed air handlers tend to work better than their single-stage, single-speed counterparts, but not so much when they're not called on to operate.

Not looking to pick a fight, but your specific example isn't the best illustration of the point you wish to make.

There is no need to pick a fight with someone who is willing to have a productive discussion. Even if we agree to disagree it can be a good learning experience.

increasing the air temperature from 72F outdoors to 78F indoors decreases relative humidity about 20 percentage points by itself.

I understand what you are saying. So if the rise in temperature drops the relative humidity from 99% to 79%, then the AC would need to bring the relative humidity down to 42%. That is still a significant decrease in the amount of moisture in the air. The point I was trying to make it is possible on very humid days for my AC to lower the humidity and not over cool the house. The cool to dehumidify feature works well in my case. But it may not work well in every house in every climate.

The challenge is dehumidifying a home when the outdoor and indoor temps are close to (indoor) setpoint temperature, which is the case in "shoulder" seasons.

Heat pump inverters are not popular in the New York City metro area due to high cost of electricity and the relative low cost of natural gas.

Not true. There is a popular Mikey Pipes HVAC / Plumber you tuber who installs Bosch as well as other systems in and around New York and Long Island area. I watch his content occasionally just for entertainment purposes.

Just because the Inverter is a HP doesn't mean you can't use it for an AC only operation. When considering other choices it becomes really clear why. (comparing systems that are apple to apple comparison.)

While air conditioners do indeed function to dehumidify indoor air, their ability to do so is limited to times when they are operating. If there is no call for air conditioning, their ability to dehumidify is zilch. Some of the more sophisticated systems will have a dehumidification mode,

I don't view this as a fight. I view this as a discussion to help those that may be struggling in understanding the complexity of it. (climate concerns just as much as opinions vary like the wind why think of this as a fight?)

Charles and I often disagree but this little snippet of his is accurate. Even in my climate of Katy, Texas for people that choose the Bosch Inverter. I tell them there is no dehumidification when the unit is off. To get dehumidification it's as simple as dropping temperature at the T-stat a degree or two.

There are some occasions for even this hot, humid climate I live in to drop to a lower temp even with an Inverter. On some occasions you might be in the 70 degree range. Those that see that number from a cooler climate may say 70 degrees is too hot. Without factoring in the role the dehumidification plays. Today in my office 46% RH.

Your climate, whatever it is -- your body gets accustomed to a particular parameter of comfort. Assigning a temperature number to it doesn't tell the whole story accurately due to the humidity or lack thereof parameter.

So let's not think of this as a fight. Ok?

The challenge is dehumidifying a home when the outdoor and indoor temps are close to (indoor) setpoint temperature, which is the case in "shoulder" seasons.

Exactly. I'll just add that the inverter that steps up and down in 1% increments like that of the Bosch Inverter will make this less challenging in that over cooling is less of an issue because of the 1% up and down steps. There are intermittent times of the year I may set my T-stat to 70F at night, primarily to dehumidify.

There are other brands than the Bosch that do the 1% steps up and down. However, they use expensive proprietary controls (communicating) to operate the system.

Not true. There is a popular Mikey Pipes HVAC / Plumber you tuber who installs Bosch as well as other systems in and around New York and Long Island area. I watch his content occasionally just for entertainment purposes.

Mikey Pipes is located in Valley Stream NY in Nassau County Long Island. The area has many homes which were built more than 50 years ago with no central AC and heating boilers burning fuel oil. The Bosch heat pump would be a good solution as a retrofit in these homes. We could call Mikey Pipes and ask him how many gas fired boilers and furnaces has he removed and replaced with a Bosch heat pump. The price of electricity of Long Island is very high, so I suspect the number is small. The is the reason I said it is not popular.

Yeah NY is a completely different market than mine.

But if the price of electricity of any area is HIGH, and that area wants air conditioning + dehumidification that is better that would be a reason for an Inverter.

I think what's causing you to trip up Mike is the heat pump classification. Just because it's a heat pump does not mean it can't function as AC only. I sell them as AC only all the time. I have mine set at a HP because I have electric heat. It's a matter of configuration + what it can do for you.

If someone doesn't have AC now, meaning more mild climate trying to sell them an Inverter maybe quite the challenge. Unless of course you have a market with large amounts of disposable income. Money is no object sort of thing. I can tell you that is not my market 90% of it at least. People move here (Texas) for work, not to stay for life. Texas life & climate and so on isn't for the faint of heart. I've lived up and down the central USA. No two places exactly alike. Texas is most brutal climate I've ever lived. I say this after over 20 years of living here.

Chicago area was brutal as far as cold, but you just layer up to deal with that. Taking off clothes in Texas isn't going to be comfortable without AC. So you understand the point.

I see some of these homes Mikey Pipes goes to... you don't get there without spending $money$. There was one video recently where his customer had like 9 different AC units.

The most I've ever seen here in Texas is 4 or 5 HVAC systems at one house.

I understand a heat pump can be used for cooling only. If a homeowner can by a Bosch heat pump for about the same price with the same efficiency as an AC only condenser, then homeowner may make that decision. I know you will say the Bosch design is far superior. But unfortunately AC equipment is sold mostly based on SEER ratings. You can tell them about the other features, but what they really want to know is how much does it cost and how much money will I save with this new equipment.

The other thing at play is name brand recognition. People know Trane, Carrier, Lennox, and York in the NY area. They may hesitate on buying a brand none of their neighbors use. I will say Bosch makes an excellent dishwasher and has displaced Kitchenaide as the best in class in my opinion. Maybe someday it will happen with heat pumps.

Bosch has excellent heat pumps. I like their designs. IDS 2.0 fixed some design issues on the 1st generation units.

But at the end of the day, an appropriately sized system/ducts (manual j/d/etc) + air sealing of a home + fresh air intake/ERV/HRV/etc will give you 'comfort' and lower heating/cooling bills over the long term.