Humidity control in winter

[Elcam84]

Originally Posted by jeff5may

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.

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.

[jeff5may]

Originally Posted by ECO20

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

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.

[u3b3rg33k]

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.

[Elcam84]

Originally Posted by jeff5may

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.

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.

[jeff5may]

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.

[johny rryan]

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