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Elcam84 02-04-19 06:25 AM

Humidity control in winter
I live in Texas where it is always humid. We can be at or below freezing and the humidity can be 80%. So no bathroom vent fans or cooking or whatever is not to blame in fact if you run them you will increase the indoor humidity by pulling in air with more humidity than is being sucked out of the house....

Unfortunately there is little done in this field because 99.999% of home performance research and information is into the simple act of keeping a house warm in a cold climate as the researchers only tackle the low hanging fruit...

Our house is roughly 1700sqft and I need a few recommendations on dehumidifiers that are relatively quiet and efficient. Unless someone knows of some other magical way of reducing indoor humidity. Looking for a real dehumidifier not one of those peltier junction ones that barely removes any moisture.

Oh and recently we have gone from the low 40s up to 79* yesterday (warmer today) and all that time the lowest the humidity has been is 87%. It's 56* right now and 99% humidity.... Yeah nasty sticky weather. I miss growing up in Hawaii where the air was drier...

stevehull 02-07-19 08:27 AM

I am a big believer in ERVs. Condition the house and an ERV allows ventilation without pulling in humidity.

In central Oklahoma, where I live, May and June have oppressive humidity. The below suggestions allow me to keep house humidity below 55%.

A good dehumidifier can lower humidity, but watch out for dryers in the conditioned space. They suck out 300-600 ft3 per minute. That will evacuate a house of conditioned inside air with just one dryer run.

1) Button up house (to reduce air infiltration)
2) use a good dehumidifier or properly sized AC unit) - or both
3) install ERV that runs at low speed (20-40 ft3/min) all the time

Elcam84 02-07-19 09:31 AM

My problem with humidity is in the winter. There is no dry air inside or out so it doesn't matter how well the house is sealed since I have nothing inside the house running in the winter to remove moisture other than the fridge which there is no easy way to put a drain hose on the pan and drain it out of the house...

Right now its 35* and the humidity is 90% hence why I need a dehumidifier in the winter. I't humid year round here with only a few exceptions of the odd dry cold front in the winter but that only stays dry for a day.

NiHaoMike 02-07-19 06:25 PM

Read up on how relative humidity works and therefore why HRVs do work as dehumidifiers during the winter.

stevehull 02-07-19 09:33 PM

Mike, hrv or erv? And why . . . .

CrankyDoug 02-09-19 07:26 AM

I have two standalone dehumidifiers (one for each floor) and have never had trouble with them. They use AC compressors and consume about 700W. It isn't really wasted heat when you are heating the house anyway.

Mine can each remove about four gallons of water a day. We turn on the downstairs unit when hanging clothes to dry. The upstairs unit rarely gets used.

Edit: Forgot to mention, this type of dehumidifier works best if you turn the dial all the way up so it runs continuously until the tank is full. When it shuts off, empty the tank and let it run again if the air is still damp. Don't forget to wash the tank occasionally or you will have mold and bacteria growth.

Elcam84 02-09-19 12:03 PM


Originally Posted by NiHaoMike (Post 60572)
Read up on how relative humidity works and therefore why HRVs do work as dehumidifiers during the winter.

They do but with the amount of humidity we have in the winter it's like peeing into the wind. Yeah you make headway but not much.

Not to mention I have nowhere to put an HRV and running the inlets and outlets would be even more difficult. Unfortunately we don't have basements nor a massive attic to place a unit. The only location would be in the garage then cut holes in the brick for two vents then pop into the attic and tun those lines across the garage to the house. Just doesn't work well in most houses here for a retrofit. We also don't have mechanical rooms either.

AC_Hacker 02-10-19 06:20 PM


Originally Posted by stevehull (Post 60570)
I am a big believer in ERVs. Condition the house and an ERV allows ventilation without pulling in humidity.

S.H.: You may want to review the operational theory of both HRVs and ERVs. I think you meant to say HRV, as the ERVs employ a semipermeable membrane that keeps the from losing moisture.

This is from Venmar, they manufacture both HRV and ERV:



Heat Recovery Ventilator (HRV):
The heat recovery ventilator (HRV) is the proper choice in colder climates where there is excess humidity during the heating season, since it can eliminate it.

The HRV keeps the home supplied with a steady flow of fresh outdoor air. As stale, warm air is expelled, the heat recovery core warms the incoming fresh, colder air before it is distributed throughout the home.

The result is a constant supply of fresh air, no unpleasant drafts and greater home comfort.

Energy Recovery Ventilator (ERV):
The energy recovery ventilator (ERV) is suitable for colder climates, in homes where there is no humidity excess during the heating season, as well as for warmer climates homes with high outdoor humidity.

The ERV recovers heat (like the HRV); however, it also recuperates the energy trapped in humidity, which greatly improves the overall recovery efficiency.

In conditioned homes, when it is more humid outside than inside, the ERV limits the amount of humidity coming into your home.

For homes using a humidifier, whit low humidity level in winter, the ERV limits the amount of humidity expelled from your home.



jeff5may 02-11-19 10:52 PM

There seems to be a misconception about relative humidity here. Your 35 degree saturated outdoor air contains less than 30% relative humidity at 68 degrees. It's all about dew point.

ECO20 02-21-19 03:10 PM

Perhaps it is better to use a central air conditioning system with one dehumidifier for the whole house for such humid conditions.

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