Well, we're into the dry season now.  My wife is already grumbling about the house being too dry, even though I'm getting readings right around 50%. 

Had a preliminary chat with my installer, who recommended against a standard bypass humidifier, since the lower temps of a geo system will make that less effective.  His thought was a duct-installed unit that is essentially a boiler pan, which fills with water which is then heated to boiling to supply moisture.  The pan is automatically drained to avoid stagnant water.  Cost would normally be $1500 installed.  Plus of course the operating expense incurred by the heater.

Thoughts on this type of system?  I'm a little worried about the electric consumption, but one way or the other the water represents a heat load I suppose.  And the alternative is a bunch of room units running overnight, which isn't free either.

Install-wise, catching a return is easiest, but then you're running moisture-laden air over the blower all the time.  Even if I can catch the supply, we're then running the moisture over the dampers (which I suppose you'd be doing in any case).  Don't know how much of an issue that really is.

I can save some money by skipping a drain pump and just having it gravity-feed into the same pipe as the drain off the air handler.  His concern was the pipe freezing in the winter, but I don't really see how a pump fixes that.  The current drain is a 1" (or so) PVC pipe that comes off the air handler, drops 6", goes horizontal for 3 feet, then through an R19 exterior wall, then elbows down for 3'.  The tail sits about 1' off the ground.  So I'm not sure where I'd have a freezing issue, and I'm unclear how a pump really changes the dynamic.

I've also seen atomizing units, although I'd be a little concerned about maintenance on those (thinking mostly of deposits building up on the spray head).  But you'd skip the heating cost of the boiler and eliminate the need for drainage.

Any insight appreciated.

with a starting point of 50%, adding a substantial amount of humidity is a recipe for trouble. Do you have an opportunities for air sealing, that will keep moisture in the house, while saving energy as opposed to consuming it.

I wouldn't humidify past 50%.

Need to be sure that reading is accurate. I have found many cheap humidity meters to be wildly (10+%) inaccurate.

Google hygrometer salt test for a nifty way to check a portable instrument. Don't do it to a system thermostat, though.

Consider adding houseplants for additional humidity. Fewer maintenance issues and there are other IAQ benefits as well. Of course you'll need to haul them outside during summer to lose the added latent load.

Agree that 50% is a sound upper limit.  My intention in quoting that figure is to demonstrate how sensitive some of us are to low humidity.  So if I'm hearing complaints at 50%, it's pretty clear that we'll have to do something as the humidity shoots downward this season.

I have also added a grand piano to the mix, which doesn't like to see humidity drop below 42% before you start to have concern about long-term damage.  So keeping things between 40-50% this winter is my goal.

I'll look into the calibration of hygrometers.  Although for what it's worth, I have two of them next to each other and they are usually within 1-2%.  And those rarely differ from the system thermostat's humidity reading by even 5%, usually more like 2-3%, and the thermostat is in the next room.  By "2%" I would mean that one might be reading 48% and the other 50%.

Then yours are probably OK.

Consider recalibrating your wife, instead.

I'm familiar with issues with musical instruments - they don't like to be too dry, too wet, too cold or too warm. My dad had pianos for years in New England and often paid for them to be retuned.

I have and like an atomizing unit, but only use it with reverse osmosis (RO) water. Otherwise, you are creating dust.

I checked into humidifiers this past spring, but never bought one. Honeywell has a TrueSteam (I believe that is the name), Seems like a good unit but it would use a lot of electricity though.

Desert Spring has an interesting unit. Here is the info: ROTARY DISC FURNACE MOUNT HUMIDIFIER Model #: DS-3200. If the marketing information can be believed, it seems to have low water and electricity usage. Here is a link:

http://www.desertspringproducts.com/desertspring/humidifiers_rotary.asp

Water Furnace recommended this humidifier at the time we bought our geothermal system earlier this year. I have no idea if it works well or not. Does anyone have any first hand experience with this unit?

You didn't mention if you had an HRV or not but if you do simply run it less often.

If you're in a newer house you should have too much moisture.

Another option if you don't have an HRV is don't run bath fans when taking a shower. That'll add a fair bit of humidity.

Not a good idea. Not running bath fans will create localized and persistent areas of very high humidity. That is conducive to mold, mildew and rot.

Using RO water in an atomizing unit may be cheaper than units that boil water, depending on the cost of RO water.

Boiling a pint of water into vapor requires about 1000 Btu, about 3-4 cents of electricity at national average rates.

I used to force the furnace fan on when taking a shower in the winter. This was enough to keep the humidity down in the bathroom without wasting the heat and humidity.

If you use an electric dryer, this is also a source of "free" heat/humidity.

Lint, and, in the case of propane or NG dryers, CO are also added to the home, free of charge, as well. A true bargain!

If one can't figure out how to filter out lint, they aren't trying very hard.

Filtering lint isn't hard. Getting the homeowner to maintain a filter IS hard.

A couple days ago I read in the local paper that clothes dryers cause 16,000 structural fires per year. I wouldn't want to sell or install anything likely to increase that already high statistic. Anything extra placed in the dryer vent air stream can't avoid lint buildup.

Personally, I'd take an easily visible, accessible filter over the long hidden, small duct runs that evidently cause fires. My parents vented their dryer internally during the winter and I think the filter was cleaned once per season.  But I expect the code guys don't agree with this.

Or just use a heat pump or condensing dryer.

I agree and agree. I wouldn't recommend venting an electric dryer inside to someone unless I know they would be good about changing the filters out. We vent ours inside and I had a 16x20 box built for with two filter spots and a pressure bypass before the second filter. The first filter is a cheap regular filter and the second one is a merv 11. There is a bypass exhaust that is spring loaded between the two incase the second filter gets to dirty the air can escape out the side, but other than physically blocking the second filter I have never seen it open. Although having done this I should have put the bypass before the first filter since that one gets the dirtiest the fastest, but I check them regularly. It is also in the basement shop area, adjacent to the living space, all in conditioned space.

We also don't vent exhaust our bathroom in winter, but it is in a circle between the master bed, master closet and living space, so we just run a fan for 30 minutes after a shower and it is circulated pretty well around the house. I just can't bring myself to dump the heat and humidity when we need both in winter.

Again having said what we do, you do have to make sure the bathroom is well ventilated and the filters are clean on the dryer or you’re asking for trouble, and I wouldn’t consider it on a non-electric dryer.

The pressure relief is a good idea - if you don't clean the filters, you merely get lint in the house.

A Honeywell True Steam (and likely some of the other brands) can be mounted remotely to avoid freezing issues.
Joe