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...

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

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.

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

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

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.

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.

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:

URL: https://www.venmar.ca/23-detail-faq-...d-an-erv-.html

Best,

-AC

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.

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

That is true but not the whole story. That 35* air is the low at night. What happens is that during the day it is in the 60s ish and the humidity averages around 70% but often as high as the high 80s. So that humid air during the day is very close to interior temps then as it cools down at night the cooler air can't carry the moisture so it creates dew on everything. Then in the morning everything is soaken wet and as it warms up the air picks up that moisture again.

So yes for a few hours at night everything is in your favor to lower interior humidity but for the majority of the day you can't make headway. Also this is why it's common for commercial properties like restaurants to run the AC at the same time as the furnace int he winter to heat but also dry the air.

So yeah if you look at the narrow point of the humidity % being high when temps are at their lows then yeah using air from outside will lower interior humidity but that time period is very short here. It warms up very quickly in the morning here. It's not uncommon to start out below freezing and end up at 80* after noon.

Good point here. The big question is how are you heating and cooling the house now? Lots of ifs and not much specific information given besides local climate conditions. If I had low cash and minimal extra space, I would snatch up a smallish twisty knob window shaker and run it on dehumidify or low, and put it in the shower stall for a quick test run. I have no idea if you even have a shower, so ymmv.

look into a whole house dehumidifier. don't even look at anything under 100PPD if you care at all about your energy bill. the rules are different for 100PPD+, mandating a significant difference in efficiency, and thus operating cost.

Typical 1960 brick ranch house in TX around 1700sqft. And no i will never have a window unit in any house i live in, well the shop does have a 2 ton but it's undersized.

Right now I have demoed the master bedroom and am integrating the hallway into it as it needs the room for the bigger bathroom and the hallway was basically unused. I'm thinking the best route will be to add a small minisplit in the master bedroom. It would serve dehumidify needs year round and I can keep the bedroom colder at night so I can sleep in the summer without having to keep the whole house colder. I sleep much better when it's around 60 to 65*

The existing window on one wall is a 3,0 X 5,0 and I will be replacing it with a wider window but higher off the floor (brick work). So I will be able to drill a hole in the concrete foundation and run the lines inside the wall for a nicer install.

FYI those tall windows they love to put in houses here are a massive heat load even when fully shaded and modern windows not to mention you end up without a wall to put furniture on. Every wall has a door or a floor to ceiling window. Tall windows are a horrible decision.

Oh and the question of utility costs. Our highest elec bill was about $220 about 5 years ago when we were hitting 117* every day for two weeks and the lowest temp was 81* and it still 95* after midnight. But that was before we changed elec plans and our rate is much better now and that bill would be about $175 under the current plan.
Our last months elec bill was $80 ish forget the KWH usage but that includes my shop and I have been running the two 60 gallon air compressors a bunch lately cutting apart and welding back together a 66 mustang. I love airtools and they are horribly inefficient but the best tool for the job.

Haha, I sniff those corks like crazy, just don't go out in the garage. Priceless.

I was saying to run a trial with something cheap and of known BTU value, so you can get an idea of what you really need. A Craigslist special 20 dollar 5000 BTU window AC set on low cool and coldest the thermostat will go will plain whoop a 300 dollar eco green Whirlpool gold platinum dehumidifier all day long. It's winter, the thing will heat up the house and dehumidify the air.

There are certain methods to control humidity at indoor.
Use indoor plants that absorb humidity
Run exhaust fans
Apply mould removal procedure
Add wood flooring