sometimes it's not the temperature that bothers us, it's the humidity. if the temp is 75-80F but humidity is very high, we turn on the AC. I think it would be more energy efficient to reduce humidity.

i think I would like to try a small unit, something that we can run in the living-room and empty once per day. The house has 2 levels, 600 st ft each. I may even get 2 units.

Any recommendations?

Thanks

Paul F. has one running all the time because of moisture IIRC.

A properly sized AC unit when allowed to run, will remove moisture from the area in which it's operating. If the area gets too cold without a corresponding reduction in the humidity level, that is a sign that the AC's thermostat should be raised (set to a higher temperature setting) so that the humidity is reduced along with the temperature. Check that the condensate the AC pulls out of the air can drain away properly and doesn't pool. Fans can help to move the cooled, drier air, around the room or house and, help the AC do its' job with greater efficiency.

I don't think he's wanting to replace his HVAC just yet.

Our inlaw's old house has 2 (used to be 3 until one died) in the basement. Each hangs on a wall and is plumbed to the outside. All year long they turn on and off based on whatever setting they're on. Works great for down there since there's only one HVAC vent supplying the whole basement (don't ask why, long story, weird house.)

But the best solution, by far to humidity control was at our previous place. In a moment of insanity I bought a $10,000 HVAC system to replace the broken A/C and about-to-die furnace. This was when a standard HVAC system replacement woulda cost about half that for that house.

The headline feature was a variable speed blower in the furnace portion (with the A/C portion obviously setup to use it): You never actually heard the HVAC kick on, never really felt air coming from the HVAC vents. Separate humidity and temp control.

Year 'round comfort, no blasts of cold air in summer freezing you and no blast of hot air in winter. And yeah it could run in spring or fall to reduce humidity when temperature change alone wouldn't kick on a standard HVAC. Oh my, but it was magic. No better major upgrade to a home is possible IMO.

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testcase
A properly sized AC unit when allowed to run, will remove moisture from the area in which it's operating. If the area gets too cold without a corresponding reduction in the humidity level, that is a sign that the AC's thermostat should be raised (set to a higher temperature setting) so that the humidity is reduced along with the temperature. Check that the condensate the AC pulls out of the air can drain away properly and doesn't pool. Fans can help to move the cooled, drier air, around the room or house and, help the AC do its' job with greater efficiency.

Thanks but that is not what I want. If temperature is 80F and humidity I’d say 80% (an example made up but not unlikely), I may want to keep it at 80F and reduce humidity to 35%. Can an AC do that?

And for the record, AC works properly, it is properly sized, and drain is checked periodically.

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testcase
A properly sized AC unit when allowed to run, will remove moisture from the area in which it's operating. If the area gets too cold without a corresponding reduction in the humidity level, that is a sign that the AC's thermostat should be raised (set to a higher temperature setting) so that the humidity is reduced along with the temperature. Check that the condensate the AC pulls out of the air can drain away properly and doesn't pool. Fans can help to move the cooled, drier air, around the room or house and, help the AC do its' job with greater efficiency.

Actually, if the humidity doesn’t drop with the temp, then your AC unit is not properly sized for the area - meaning it is too big for the area.

---

Saint Cloud, Minnesota, where the weather is wonderful even when it isn't.

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space-time
And for the record, AC works properly, it is properly sized, and drain is checked periodically.

Open your windows on those tween days.

---

Saint Cloud, Minnesota, where the weather is wonderful even when it isn't.

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Speedy

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space-time
And for the record, AC works properly, it is properly sized, and drain is checked periodically.

Open your windows on those tween days.

humidity is also high outside. how does that help?

To answer the question: Lowe’s has a good selection. Hisense, GE. Both good products. Look for those that have a pump built in. You can snake the pump hose to a drain and then let the machine go indefinitely. Has saved my downstairs many a time.

AC should reduce the humidity if it is running often enough. An oversized system will not reduce humidity much because it runs less often.

An undersized system will drop the humidity a lot more. If your current system has variable compressor loading, there is a chance it could be set to reduce humidity. You would need to add a humidity meter to the control system.

I don't have any recommendations on a reliable model. Be aware that they can take a fair amount of energy to run. GE APEL70LW "70 pint" with built in pump is rated for 690 Watts (that's 55 LED bulbs). It will run continuously until it hits the humidity setting.

---

In tha 360. MRF User Map

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testcase
... If the area gets too cold without a corresponding reduction in the humidity level, that is a sign that the AC's thermostat should be raised (set to a higher temperature setting) so that the humidity is reduced along with the temperature. ...

This part I do not understand. if I raise the thermostat set point then the AC will not run at all. My AC is controlled only by the temperature, there is no set point for humidity.

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Filliam H. Muffman
AC should reduce the humidity if it is running often enough. An oversized system will not reduce humidity much because it runs less often.

An undersized system will drop the humidity a lot more. If your current system has variable compressor loading, there is a chance it could be set to reduce humidity. You would need to add a humidity meter to the control system.

I don't have any recommendations on a reliable model. Be aware that they can take a fair amount of energy to run. GE APEL70LW "70 pint" with built in pump is rated for 690 Watts (that's 55 LED bulbs). It will run continuously until it hits the humidity setting.

Thanks. I guess you are right, but I admit that I do not fully understand the explanation about oversized and undersized AC units. If the unit runs 10 min to reduce the temperature from 80 to 75F, it means it takes in a large amount of air that it cools and that air should come out less humid. If a smaller AC unit would take 20 min to cool the same room from 80 to 75, it means it takes less air per minute, but after 20 min the same amount of air would run through the coils and I would expect the same amount of moisture to be removed from the room.

Let's think about it his way: supposed I have 2 identical AC units (window mounted), side by side.

Supposed they are controlled by one external thermostat in the other side of the room. both unit wired to the same thermostat.

If I use only one, it runs at 50% duty cycle (cycle every 10 min on, 10 min off). one unit removed 2 oz of water in this 10 min

if I use both of them, they start at the same time, they run 5 min, then they sit idle for 15 min. each unit removed 1 oz in those 5 minutes, but together they remove 2 oz.

So can I think of the 2 units together, combined, as an oversized AC unit? what if you were to put a box around the unit and you don't know if inside is 2 units, you could think there is only 1 unit. Why would this "combined" (oversized) unit remove less water than the properly sized unit?

maybe the model I have in my mind is too simplified or too abstract.

sorry for ranting.

Hi everyone,

As an FYI, an AC can only reduce the humidity so much. Even when properly sized for a given room and its environment.

In the high humidity months of Long Island which can run from June through September, I have to run three ACs and a 50 pint per hour dehumidifier to keep the apartment comfortable. Not 24/7. The ACs and our Danby humidifier all have timing functions and activate or deactivate per the time frame of my choice.

We use these to gauge the temperature and humidity in our bedrooms and living room/kitchen:

[www.amazon.com]

Filliam is spot on about the energy used by a dehumidifier. It's on part with the energy used by an air conditioner. The better ones are energystar rated and can qualify for an energystar rebate. You have to check with your local utility to see if they offer one.

Our Danby model has proven rock solid-reliable for many years. Unfortunately, based on everything I've read, all dehumidifiers break down after a few years. It's not a matter of if. It's a matter of when and brand doesn't make a difference. So, buy the size and model that offers the best warranty.

The Danby can be connected to a hose for continuous water removal but we can't really do that in our apartment. I empty the bucket as necessary. The Danby turns off automatically when the bucket fills completely.

Dehumidifiers can be noisy. The Danby isn't the noisest model on the market but it is definitely annoying loud enough that we prefer not to run it at night.

here are some links that might be helpful:

[www.dehumidifierbuyersguide.com]

[www.goodhousekeeping.com]

Note, some dehumidifiers are made by the same OEM and sold under different names with minimal differences.

Robert

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Robert M
Unfortunately, based on everything I've read, all dehumidifiers break down after a few years. It's not a matter of if. It's a matter of when and brand doesn't make a difference.

I inherited a dehumidifier from my grandparents. 1950s model, heavy duty steel construction, weighs a ton. Still getting the job done in my basement more than 60 years later. I've never done any maintenance to it. Probably an electricity hog, but I'll live with that.

tronnei,

Sounds similar to the one my granddad had in the basement of his house. Worked well but efficient it was not. Most definitely not.

Robert

Similar to tronnei, I inherited a heavy vintage beaut from the inlaws to use in the basement. Faux wood paneling. Original patina. Hah!

After a little more reading it appears the linear model I have in mind is oversimplified. They start reducing moisture after 10-20 min so if they are oversized and run only 5-10 min they do not remove much water.

My unit does remove moisture since I need to keep the drain clean, otherwise it can flood. I put a sensor to alert us if that were to happen.

You're overthinking the size/capacity/tonnage issue. And really, that's for the professional installer to assess via measurements. If it's too large, the air cools down very quickly but leaves humidity behind because that takes longer to do. It's why a house can feel cold and clammy. Probably a heavy air vs light air circumstance.

That's also why an undersized AC might struggle to keep the house cool but be better at scavenging humidity: it has longer to operate because it "must." The multi-stage, variable setup I described above runs fewer but longer cycles and at lower fan RPM, lower compressor RPM. It's great to be outside and not even hear the AC compressor running unless you walk up to it. Your neighbors will thank you.

In other words yes, temp and humidity are obviously highly related but their deltas aren't 1:1. FYI you don't want true humidity of 35% unless you like nose bleeds and scaly skin. An HVAC with separate humidity control can take it down to about 50-60% and trust me, that's plenty low to feel fresh and healthy. A regular one-stage AC system can never do that.

*******************

If getting a new HVAC the guy giving a quote will do one of two things.

1) Walk around and show you a brochure of good-better-best of whatever size you currently have.

2) Walk around, measure each room, note where existing vents and returns are, and either say it's fine or recommend new/different vents and/or a different size AC unit. In other words he'll let the house dictate what's needed by computational analysis, not the previous installer's opinion.

*******************

Fun fact: Way back in college I shared an apartment with 2 other dudes. The heater/AC unit always blasted its fan. It was loud and there was a hurricane coming out of each vent. Ridiculous.

Out of curiosity I opened the cover to where the blower motor was and noticed it could be wired for 3 different speeds just by swapping the wires onto different terminals. I changed it from HI to LO and a "miracle" occurred.

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deckeda
...

But the best solution, by far to humidity control was at our previous place. In a moment of insanity I bought a $10,000 HVAC system to replace the broken A/C and about-to-die furnace. This was when a standard HVAC system replacement woulda cost about half that for that house.

The headline feature was a variable speed blower in the furnace portion (with the A/C portion obviously setup to use it): You never actually heard the HVAC kick on, never really felt air coming from the HVAC vents. Separate humidity and temp control.

Year 'round comfort, no blasts of cold air in summer freezing you and no blast of hot air in winter. And yeah it could run in spring or fall to reduce humidity when temperature change alone wouldn't kick on a standard HVAC. Oh my, but it was magic. No better major upgrade to a home is possible IMO.

Hi, I am curious if this setup required a special thermostat. Once the thermostat decided that it needs to cool down the place (or heat it), how did the furnace know how fast to blow the fan? I assume for small temperature differences the fan runs very slow, but most thermostats only indicated ON or OFF, they do not have a control to indicated how fast the furnace should run. I am positive that my previous Honeywell $30 programmable Thermostat could not do that, and I think Ecobee also cannot do that, but I could be wrong.

Thanks

Most AC systems don't have a humidity control because they don't have the more expensive variable/multi-speed compressor/circulating fan (edit: or a humidity meter). If a system has the functions available and you want to maximize the moisture removal, cut the flow of refrigerant to the minimum and then progressively slow down the air flow until just before the compressor cuts off due to the evaporator hitting a low temp trip/alarm (typically 3-8 °F before it starts to freeze up).

Edit/note: I am not an AC tech. For a while I was the computer/network tech at a community college, and was able to use a computer simulator for a class in refrigeration when I was really bored.

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In tha 360. MRF User Map



Edited 2 time(s). Last edit at 05/29/2019 12:45PM by Filliam H. Muffman.

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space-time

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deckeda
...

But the best solution, by far to humidity control was at our previous place. In a moment of insanity I bought a $10,000 HVAC system to replace the broken A/C and about-to-die furnace. This was when a standard HVAC system replacement woulda cost about half that for that house.

The headline feature was a variable speed blower in the furnace portion (with the A/C portion obviously setup to use it): You never actually heard the HVAC kick on, never really felt air coming from the HVAC vents. Separate humidity and temp control.

Year 'round comfort, no blasts of cold air in summer freezing you and no blast of hot air in winter. And yeah it could run in spring or fall to reduce humidity when temperature change alone wouldn't kick on a standard HVAC. Oh my, but it was magic. No better major upgrade to a home is possible IMO.

Hi, I am curious if this setup required a special thermostat. Once the thermostat decided that it needs to cool down the place (or heat it), how did the furnace know how fast to blow the fan? I assume for small temperature differences the fan runs very slow, but most thermostats only indicated ON or OFF, they do not have a control to indicated how fast the furnace should run. I am positive that my previous Honeywell $30 programmable Thermostat could not do that, and I think Ecobee also cannot do that, but I could be wrong.

Thanks

What we bought was a dedicated system. The old days of using a generic t-stat with any furnace and AC are gone unless you get a very basic, older style of system. There are of course in-between setups, like the fancier replacement thermostats you can buy at hardware stores with extra controls compatible with what you have. But those can't add functionality that doesn't exist within the furnace and AC.

We bought a Carrier Infinity system. The thermostat was programmable and of course had humidity contrtol. Today they look like smartphone/Nest displays. Back when we got ours, WiFi / Internet control had recently come out but we didn't get that option. The proprietary interface board was expensive and only offered minimal remote control that we never missed.

The replacement furnace was a traditional "80% efficiency" type (gas); we couldn't justify the 90% or 95% efficient kind down in Georgia. We spent a bit more on the AC portion, but it was really just a 15 or 16 SEER unit.

I mention the furnace because the old one was working. But it had two issues. The main one was that unbeknownst to us it was mostly rust inside. Probably would have failed the following winter. The second was that it lacked the variable speed blower and so on the new AC unit needed in order to do its thing. If buying an AC system, don't ever be surprised you'll also be buying a new furnace also. It is what it is.

You have to balance those choices based on where you live. In Florida I'd aim for a high SEER AC unit since it runs so much. Up north many people can justify a 90 or 95% efficiency furnace, assuming they'd use natural gas.

When we sold the house, the idiot inspector our buyers hired included in his report that the HVAC system was "all wrong" because a 2 storey house should have 2 HVAC systems and so gosh, they wanted an additional mega-thousand discount off the price of the house.

That, along with other similarly silly requests, didn't happen. I thought it was interesting you could show someone a house with a far nicer HVAC than any other house in their price range likely had, and they still didn't appreciate it.



Edited 1 time(s). Last edit at 05/29/2019 01:38PM by deckeda.

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3d
Similar to tronnei, I inherited a heavy vintage beaut from the inlaws to use in the basement. Faux wood paneling. Original patina. Hah!

Those are modern state-of-the-art models compared to mine.

We have a Danby Premiere 70-pint dehumidifierin the basement, bought new a couple of years ago from our local appliance dealer, to replace an older dehumidifier that had a problem with freezing coils. The Danby has a built-in pump, which I need as there is no drain in the basement (before I used a separate aquastat pump), and the dehumidifier runs all the time from about May to October. So far, working just fine.

/Mr Lynn

---

"Hillbilly at Harvard"
Honky-tonk Country and Bluegrass
Founded in 1948 by Pappy Ben Minnich
Saturdays 9am - 11am Eastern
WHRB-FM, Cambridge, MA
Streaming at [www.WHRB.org]
Be there!
The HAH weblog: [hillbillyatharvard.wordpress.com]

Topical weblog: [walkingcreekworld.wordpress.com]

On the river in Saxonville.

MrLynn,

Ours is the 50 pint version of your Danby Premier. It's been solid. Would definitely get another Danby if I needed to replace it.

Robert