Dealing with humidity w/o A/C ?
 

Wondering if you guys found something that worked well... My upstairs (living room /kitchen) is sunny and pretty dry. Downstairs (bedrooms, laundry) the windows are mostly covered by the upstairs deck, so it's always 10-15F cooler and 20% more humid than upstairs (65% vs 44%) - run a clothes dryer or leave a bathroom door open post shower and we're at 70% despite new venting. Which I understand is too much? Feels humid anyway. That's in a drought, post major reno with new proper fan/exhaust venting done !!! must be underground water or just less light/sun, so I wanna fix this before rainy season.

I don't want to run a dehumidifier all the time (unless you suggest something that doesn't run a high electrical bill and work well), so I was thinking of (wires permitting) installing a Nest thermostat because unlike my current no-frills one, it can control the fan "alone" on a timer - independently of heat. I would be able to, say, suck upstairs dry air (that's where the intake is) and circulate it all over the house, maybe 15m per hour every hour, without having the actual heat on.

Of course I'll need to rewire the new furnace (no A/C) to make the nest work, I've only got 2 wires coming out of it right now - 5 ports are unconnected to anything, looks like an amateur wiring job. Before I splurge $250 on a smarter thermostat and rewire, punch holes, I'm wondering if you think that'll help enough or if you've got other suggestions to lower humidity downstairs... It's not a basement but might be a similar situation....

If you own the home you have some things to be concerned about.
One is that you need to install an exhaust fan in the washroom where your shower is.
Two is that the drier should be vented to the great outdoors.
Anything that increases the humidity level in the home will decrease comfort. Except in Western Canada where we actually humidify the air in the winter to increase comfort but that is another topic.
I think that what you are experiencing is pretty normal and natural. When the temperature of the air decreases, it's ability to hold moisture diminishes. That air that you have in the lower level actually contains the same weight in moisture (more or less) as the air upstairs but you feel it is more humid as it is closer to holding all the moisture it can (saturation).
I would suggest that if you have central air conditioning or heating to run the fan in intervals during the day to even out the temperature in the home. Some programmable thermostats will have this feature.
If you are fortunate enough to have a modern fan coil or furnace that has a variable speed drive fan, they can operate low and slow at a very small cost energy wise.

There are other thermostats that can independently run the fan. I had a Filtrete thermostat. Natively, it didn't, but with a small program on my computer, it could be programmed to run the fan a certain percentage of every hour. I think the next step up had the fan stuff built in. Honeywell also makes a thermostat that has that ability.

the radio thermostat ct80 has the ability to run the fan on a timer. I think I had the Filtrete branded CT50 and used a $15 app called setmythermostat which controlled gave me the ability, but required my PC to always be on (which it is).

The Honeywell Vision Pro 8000 has a circulate mode, but it appears to be hard set to 35%. Available on Amazon for $135 or so.

I think a little research would probably yield a few others.

I've used a few programmable thermostats from HD and each had a circulate options. I use it all the time, but I dont know the interval. I dont think I spend more than $30 on any of them, no remote control but that's too complicated for me.

The above is already taken care of. Downstairs was completely renovated. Every bath is vented, so is the drier. Mind these fans could be stronger IMO, but it's up to code. I think as you and other said it's more of a factor of less light and cooler temps. If the whole house was like downstairs I wouldn't notice, but going up/down it's more obvious. Not sure what a bad humidity level is, real world: 60%? 70%?

I'm going to verify this (new) furnace can actually let me operate its fan only, I know AC can but we don't have AC. The reason I was looking at Nest (besides the fact I use to have one and I liked it) was the fine tuning of the fan programming. Seems it can do things like 15-30-45m every hour for whatever range of time you give it. Other Thermostats seemed to me more on-off...

We lived in a 2 story house built in 1967. During the summer months the upstairs/downstairs temp differential would be uncomfortably large, and would overwhelm the AC in the house. In the spring and fall, sometimes the downstairs would stay cool enough to not kick the AC on all day but the upstairs would be several degrees warmer than the downstairs making it very uncomfortable. For a couple of years, I would just kick the fan to "on". Having a circulate mode made a huge difference. You could still feel a difference between the upstairs and downstairs, but the difference was much smaller and liveable. I found that running the fan 24x7 wasn't as expensive as you would think, but of course, having a circulate mode is even better.

Good to get that moisture out.
Some good suggestions on T'stats already and the DC drive motors (variable speed) available in some furnaces dramatically cut the cost of running just the motor alone. There are retrofit motors that will do this as well.
Remember that circulating all that air will require you to change filters more often than you would normally.

What are the temps upstairs and downstairs?
10 - 15F cooler is pretty significant.
Warming the downstairs up a little will decrease humidity.
Anything over 60% starts wrinkling papers and gets uncomfortable.

Any thoughts on a whole house fan upstairs? Vents to the attic, need plenty of screened openings in the attic gables. Variable speed one on a timer? Pulls air from downstairs to upstairs. But if you have outside humidity that is high, it might not be what you're looking for.

I thought I'd report with findings... I gave up on the thermostat that came with the house... I got a Nest. Not cheap but as ever, good things never are. It's a finely crafted, packaged and implemented device, this... I like how it connects to Wifi and knows the weather in my area and adapts accordingly... They even supply stickers for wires and a personalized graphics on how to wire it, if you send them a picture of your existing setup. Top notch service...

The Nest does indeed control the fan independently of the heat or cooling. So it works a treat for my humidity issues. It helps that it has a humidity sensor that I can see on the web page as I type this, so I can track the progress, fan on, humidity drops by a couple percent in 20 seconds... But it's not so much an issue in winter as the heater dries the air pretty well... It'll be great this summer though ! It also seems much better than the el-cheapo devices at "hitting" the temps you set and not overshooting... All in all, I love it..

Got a Nest for Father's Day. My son is living here at the moment (25y/o). When I'm away I'll check and dial the temp up on him on the A/C.

Get a portable dehumidifier and put it downstairs. It will remove a couple of gallons of water each day. If you are constantly over 45% there is a serious potential for mold.

+1

I have one, fills up pretty quick... Maybe I should plumb it so I don't have to empty it every day but I like the A/C fan circulating the dryer air from upstairs too... Really not sure why humidity is that much higher down there, must be water underground flowing downhill or something... 60% is average without the heater...

Most everything downstairs is redone with vapor barrier, etc.. And under the house or by the foundation the ground is dry. It's just 20% more humid than upstairs. Odd...

+2 on what fintstone & RSBob said. The 45% to 50% is the range for mold to start. Could be you already have some somewhere. I don't have an explanation for the higher humidity but if it were me, I'd get somebody in the area who knows about those kinds of things to consult with.

Good info here:
Spier Construction » Quality, Efficiency and Integrity » Finished Basement Living Space

I had really bad humidity problems at home until I added aHoneywell dehumidifier to our HVAC system. Now it keeps things right at 50%. It was pretty to do and works with our Ecobee; your Nest is probably able to control one too.

Just to be clear: Downstairs isn't a basement, the house is built on a hillside, so it's got almost as many windows as upstairs. It's just that upstairs gets more light/sun twice a day (East and west), and therefore less humidity. The upstairs has a deck and that and some trees shield the downstairs windows from receiving as much sunlight. It's generally 10F cooler downstairs in summer, so we don't have A/C ! I've read conflicting numbers on humidity levels, too. The house was built in the 50s and there was no mold inside or outside the walls when the reno happened. Still no mold now after 8 months. Plenty of fans in all bathrooms.... Winter with occasional heater won't be an issue (averaging 50% now) but summer will be. I'll investigate a permanent dehumidifier system then, I'm not changing the buckets every day - not that I'm lazy, but sooner or later Murphy says I'll trip !!!

I have a standalone dehumidifier in my basement. You can get them with a remote drain line so no bucket emptying. Works great. Keeps the "basement smell" out of the basement. Probably takes a gallon per day out.